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  • Javascript: can I call a function in an external file from the main page ?

    - by Patrick
    hi, I'm loading from my main page an external js file, with a function. I have a flash file in the main page invoking the javascript function. Everything worked very well until when the javascript code was in the main file, but when I moved javascript to an external file the function seems not called anymore. So... there is no way to move the javascript code to an external file ? Or any other solution ? thanks

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  • Does a native php (5+) function exist that does the following in 1 line?

    - by Vinh
    function array_value_from_key($array,$key) { return !empty($array[$key]) ? $array[$key] : null; } The reason I ask is because I have a class function that returns an array. Instead of having to do $myArray = myClass::giveMeArray(); $myValue = $myArray[$myKey]; I'd like to do something along the lines of $myValue = array_value_from_key(myClass::giveMeArray(),$myKey); When an object is returned, you can chain the object such as $myValue = myClass::giveMeObject()->aValue; Voila, nice and clean.. not being able to find what seems to be a simple and trivial function is driving me crazy... PS.. one more example of how I'd like to use such a function if(arrayKeyVal(aClass::giveMeArray(),$myKey)) { do_something(); }

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  • scala coalesces multiple function call parameters into a Tuple -- can this be disabled?

    - by landon9720
    This is a troublesome violation of type safety in my project, so I'm looking for a way to disable it. It seems that if a function takes an AnyRef (or a java.lang.Object), you can call the function with any combination of parameters, and Scala will coalesce the parameters into a Tuple object and invoke the function. In my case the function isn't expecting a Tuple, and fails at runtime. I would expect this situation to be caught at compile time. object WhyTuple { def main(args: Array[String]): Unit = { fooIt("foo", "bar") } def fooIt(o: AnyRef) { println(o.toString) } } Output: (foo,bar)

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  • Python - 2 Questions: Editing a variable in a function and changing the order of if else statements

    - by Eric
    First of all, I should explain what I'm trying to do first. I'm creating a dungeon crawler-like game, and I'm trying to program the movement of computer characters/monsters in the map. The map is basically a Cartesian coordinate grid. The locations of characters are represented by tuples of the x and y values, (x,y). The game works by turns, and in a turn a character can only move up, down, left or right 1 space. I'm creating a very simple movement system where the character will simply make decisions to move on a turn by turn basis. Essentially a 'forgetful' movement system. A basic flow chart of what I'm intending to do: Find direction towards destination Make a priority list of movements to be done using the direction eg.('r','u','d','l') means it would try to move right first, then up, then down, then left. Try each of the possibilities following the priority order. If the first movement fails (blocked by obstacle etc.), then it would successively try the movements until the first one that is successful, then it would stop. At step 3, the way I'm trying to do it is like this: def move(direction,location): try: -snip- # Tries to move, raises the exception Movementerror if cannot move in the direction return 1 # Indicates movement successful except Movementerror: return 0 # Indicates movement unsuccessful (thus character has not moved yet) prioritylist = ('r','u','d','l') if move('r',location): pass elif move('u',location): pass elif move('d',location): pass elif move('l',location): pass else: pass In the if/else block, the program would try the first movement on the priority on the priority list. At the move function, the character would try to move. If the character is not blocked and does move, it returns 1, leading to the pass where it would stop. If the character is blocked, it returns 0, then it tries the next movement. However, this results in 2 problems: How do I edit a variable passed into a function inside the function itself, while returning if the edit is successful? I have been told that you can't edit a variable inside a function as it won't really change the value of the variable, it just makes the variable inside the function refer to something else while the original variable remain unchanged. So, the solution is to return the value and then assign the variable to the returned value. However, I want it to return another value indicating if this edit is successful, so I want to edit this variable inside the function itself. How do I do so? How do I change the order of the if/else statements to follow the order of the priority list? It needs to be able to change during runtime as the priority list can change resulting in a different order of movement to try.

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  • [javascript] Can I overload an object with a function?

    - by user257493
    Lets say I have an object of functions/values. I'm interested in overloading based on calling behavior. For example, this block of code below demonstrates what I wish to do. var main_thing = { initalized: false, something: "Hallo, welt!", something_else: [123,456,789], load: { sub1 : function() { //Some stuff }, sub2 : function() { //Some stuff }, all : function() { this.load.sub1(); this.load.sub2(); } } init: function () { this.initalized=true; this.something="Hello, world!"; this.something_else = [0,0,0]; this.load(); //I want this to call this.load.all() instead. } } The issue to me is that main_thing.load is assigned to an object, and to call main_thing.load.all() would call the function inside of the object (the () operator). What can I do to set up my code so I could use main_thing.load as an access the object, and main_thing.load() to execute some code? Or at least, similar behavior. Basically, this would be similar to a default constructor in other languages where you don't need to call main_thing.constructor(). If this isn't possible, please explain with a bit of detail.

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  • Registration form validation not validating

    - by jgray
    I am a noob when it comes to web development. I am trying to validate a registration form and to me it looks right but it will not validate.. This is what i have so far and i am validating through a repository or database. Any help would be greatly appreciated. thanks <?php session_start(); $title = "User Registration"; $keywords = "Name, contact, phone, e-mail, registration"; $description = "user registration becoming a member."; require "partials/_html_header.php"; //require "partials/_header.php"; require "partials/_menu.php"; require "DataRepository.php"; // if all validation passed save user $db = new DataRepository(); // form validation goes here $first_nameErr = $emailErr = $passwordErr = $passwordConfirmErr = ""; $first_name = $last_name = $email = $password = $passwordConfirm = ""; if(isset($_POST['submit'])) { $valid = TRUE; // check if all fields are valid { if ($_SERVER["REQUEST_METHOD"] == "POST") { if (empty($_POST["first_name"])) {$first_nameErr = "Name is required";} else { // $first_name = test_input($_POST["first_name"]); // check if name only contains letters and whitespace if (!preg_match("/^[a-zA-Z ]*$/",$first_name)) { $first_nameErr = "Only letters and white space allowed"; } } if (empty($_POST["email"])) {$emailErr = "Email is required";} else { // $email = test_input($_POST["email"]); // check if e-mail address syntax is valid if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) { $emailErr = "Invalid email format"; } } if (!preg_match("/(......)/",$password)) { $passwordErr = "Subject must contain THREE or more characters!"; } if ($_POST['password']!= $_POST['passwordConfirm']) { echo("Oops! Password did not match! Try again. "); } function test_input($data) { $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; } } } if(!$db->isEmailUnique($_POST['email'])) { $valid = FALSE; //display errors in the correct places } // if still valid save the user if($valid) { $new_user = array( 'first_name' => $_POST['first_name'], 'last_name' => $_POST['last_name'], 'email' => $_POST['email'], 'password' => $_POST['password'] ); $results = $db->saveUser($new_user); if($results == TRUE) { header("Location: login.php"); } else { echo "WTF!"; exit; } } } ?> <head> <style> .error {color: #FF0000;} </style> </head> <h1 class="center"> World Wide Web Creations' User Registration </h1> <p><span class="error"></span><p> <form method="POST" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" onsubmit="return validate_form()" > First Name: <input type="text" name="first_name" id="first_name" value="<?php echo $first_name;?>" /> <span class="error"> <?php echo $first_nameErr;?></span> <br /> <br /> Last Name(Optional): <input type="text" name="last_name" id="last_name" value="<?php echo $last_name;?>" /> <br /> <br /> E-mail: <input type="email" name="email" id="email" value="<?php echo $email;?>" /> <span class="error"> <?php echo $emailErr;?></span> <br /> <br /> Password: <input type="password" name="password" id="password" value="" /> <span class="error"> <?php echo $passwordErr;?></span> <br /> <br /> Confirmation Password: <input type="password" name="passwordConfirm" id="passwordConfirm" value="" /> <span class="error"> <?php echo $passwordConfirmErr;?></span> <br /> <br /> <br /> <br /> <input type="submit" name="submit" id="submit" value="Submit Data" /> <input type="reset" name="reset" id="reset" value="Reset Form" /> </form> </body> </html> <?php require "partials/_footer.php"; require "partials/_html_footer.php"; ?> class DataRepository { // version number private $version = "1.0.3"; // turn on and off debugging private static $debug = FALSE; // flag to (re)initialize db on each call private static $initialize_db = FALSE; // insert test data on initialization private static $load_default_data = TRUE; const DATAFILE = "203data.txt"; private $data = NULL; private $errors = array(); private $user_fields = array( 'id' => array('required' => 0), 'created_at' => array('required' => 0), 'updated_at' => array('required' => 0), 'first_name' => array('required' => 1), 'last_name' => array('required' => 0), 'email' => array('required' => 1), 'password' => array('required' => 1), 'level' => array('required' => 0, 'default' => 2), ); private $post_fields = array( 'id' => array('required' => 0), 'created_at' => array('required' => 0), 'updated_at' => array('required' => 0), 'user_id' => array('required' => 1), 'title' => array('required' => 1), 'message' => array('required' => 1), 'private' => array('required' => 0, 'default' => 0), ); private $default_user = array( 'id' => 1, 'created_at' => '2013-01-01 00:00:00', 'updated_at' => '2013-01-01 00:00:00', 'first_name' => 'Admin Joe', 'last_name' => 'Tester', 'email' => '[email protected]', 'password' => 'a94a8fe5ccb19ba61c4c0873d391e987982fbbd3', 'level' => 1, ); private $default_post = array( 'id' => 1, 'created_at' => '2013-01-01 00:00:00', 'updated_at' => '2013-01-01 00:00:00', 'user_id' => 1, 'title' => 'My First Post', 'message' => 'This is the message of the first post.', 'private' => 0, ); // constructor will load existing data into memory // if it does not exist it will create it and initialize if desired public function __construct() { // check if need to reset if(DataRepository::$initialize_db AND file_exists(DataRepository::DATAFILE)) { unlink(DataRepository::DATAFILE); } // if file doesn't exist, create the initial datafile if(!file_exists(DataRepository::DATAFILE)) { $this->log("Data file does not exist. Attempting to create it... (".__FUNCTION__.":".__LINE__.")"); // create initial file $this->data = array( 'users' => array( ), 'posts' => array() ); // load default data if needed if(DataRepository::$load_default_data) { $this->data['users'][1] = $this->default_user; $this->data['posts'][1] = $this->default_post; } $this->writeTheData(); } // load the data into memory for use $this->loadTheData(); } private function showErrors($break = TRUE, $type = NULL) { if(count($this->errors) > 0) { echo "<div style=\"color:red;font-weight: bold;font-size: 1.3em\":<h3>$type Errors</h3><ol>"; foreach($this->errors AS $error) { echo "<li>$error</li>"; } echo "</ol></div>"; if($break) { "</br></br></br>Exiting because of errors!"; exit; } } } private function writeTheData() { $this->log("Attempting to write the datafile: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); file_put_contents(DataRepository::DATAFILE, json_encode($this->data)); $this->log("Datafile written: ".DataRepository::DATAFILE." (line: ".__LINE__.")"); } private function loadTheData() { $this->log("Attempting to load the datafile: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); $this->data = json_decode(file_get_contents(DataRepository::DATAFILE), true); $this->log("Datafile loaded: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $this->data); } private function validateFields(&$info, $fields, $pre_errors = NULL) { // merge in any pre_errors if($pre_errors != NULL) { $this->errors = array_merge($this->errors, $pre_errors); } // check all required fields foreach($fields AS $field => $reqs) { if(isset($reqs['required']) AND $reqs['required'] == 1) { if(!isset($info[$field]) OR strlen($info[$field]) == 0) { $this->errors[] = "$field is a REQUIRED field"; } } // set any default values if not present if(isset($reqs['default']) AND (!isset($info[$field]) OR $info[$field] == "")) { $info[$field] = $reqs['default']; } } $this->showErrors(); if(count($this->errors) == 0) { return TRUE; } else { return FALSE; } } private function validateUser(&$user_info) { // check if the email is already in use $this->log("About to check pre_errors: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $user_info); $pre_errors = NULL; if(isset($user_info['email'])) { if(!$this->isEmailUnique($user_info['email'])) { $pre_errors = array('The email: '.$user_info['email'].' is already used in our system'); } } $this->log("After pre_error check: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $pre_errors); return $this->validateFields($user_info, $this->user_fields, $pre_errors); } private function validatePost(&$post_info) { // check if the user_id in the post actually exists $this->log("About to check pre_errors: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $post_info); $pre_errors = NULL; if(isset($post_info['user_id'])) { if(!isset($this->data['users'][$post_info['user_id']])) { $pre_errors = array('The posts must belong to a valid user. (User '.$post_info['user_id'].' does not exist in the data'); } } $this->log("After pre_error check: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")", $pre_errors); return $this->validateFields($post_info, $this->post_fields, $pre_errors); } private function log($message, $data = NULL) { $style = "background-color: #F8F8F8; border: 1px solid #DDDDDD; border-radius: 3px; font-size: 13px; line-height: 19px; overflow: auto; padding: 6px 10px;"; if(DataRepository::$debug) { if($data != NULL) { $dump = "<div style=\"$style\"><pre>".json_encode($data, JSON_PRETTY_PRINT)."</pre></div>"; } else { $dump = NULL; } echo "<code><b>Debug:</b> $message</code>$dump<br />"; } } public function saveUser($user_info) { $this->log("Entering saveUser: (".__FUNCTION__.":".__LINE__.")", $user_info); $mydata = array(); $update = FALSE; // check for existing data if(isset($user_info['id']) AND $this->data['users'][$user_info['id']]) { $mydata = $this->data['users'][$user_info['id']]; $this->log("Loaded prior user: ".print_r($mydata, TRUE)." (".__FUNCTION__.":".__LINE__.")"); } // copy over existing values $this->log("Before copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); foreach($user_info AS $k => $v) { $mydata[$k] = $user_info[$k]; } $this->log("After copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); // check required fields if($this->validateUser($mydata)) { // hash password if new if(isset($mydata['password'])) { $mydata['password'] = sha1($mydata['password']); } // if no id, add the next available one if(!isset($mydata['id']) OR (int)$mydata['id'] < 1) { $this->log("No id set: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); if(count($this->data['users']) == 0) { $mydata['id'] = 1; $this->log("Setting id to 1: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } else { $mydata['id'] = max(array_keys($this->data['users']))+1; $this->log("Found max id and added 1 [".$mydata['id']."]: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } } // set created date if null if(!isset($mydata['created_at'])) { $mydata['created_at'] = date ("Y-m-d H:i:s", time()); } // update modified time $mydata['modified_at'] = date ("Y-m-d H:i:s", time()); // copy into data and save $this->log("Before data save: (".__FUNCTION__.":".__LINE__.")", $this->data); $this->data['users'][$mydata['id']] = $mydata; $this->writeTheData(); } return TRUE; } public function getUserById($id) { if(isset($this->data['users'][$id])) { return $this->data['users'][$id]; } else { return array(); } } public function isEmailUnique($email) { // find the user that has the right username/password foreach($this->data['users'] AS $k => $v) { $this->log("Checking unique email: {$v['email']} == $email (".__FUNCTION__.":".__LINE__.")", NULL); if($v['email'] == $email) { $this->log("FOUND NOT unique email: {$v['email']} == $email (".__FUNCTION__.":".__LINE__.")", NULL); return FALSE; break; } } $this->log("Email IS unique: $email (".__FUNCTION__.":".__LINE__.")", NULL); return TRUE; } public function login($username, $password) { // hash password for validation $password = sha1($password); $this->log("Attempting to login with $username / $password: (".__FUNCTION__.":".__LINE__.")", NULL); $user = NULL; // find the user that has the right username/password foreach($this->data['users'] AS $k => $v) { if($v['email'] == $username AND $v['password'] == $password) { $user = $v; break; } } $this->log("Exiting login: (".__FUNCTION__.":".__LINE__.")", $user); return $user; } public function savePost($post_info) { $this->log("Entering savePost: (".__FUNCTION__.":".__LINE__.")", $post_info); $mydata = array(); // check for existing data if(isset($post_info['id']) AND $this->data['posts'][$post_info['id']]) { $mydata = $this->data['posts'][$post_info['id']]; $this->log("Loaded prior posts: ".print_r($mydata, TRUE)." (".__FUNCTION__.":".__LINE__.")"); } $this->log("Before copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); foreach($post_info AS $k => $v) { $mydata[$k] = $post_info[$k]; } $this->log("After copying over existing values: (".__FUNCTION__.":".__LINE__.")", $mydata); // check required fields if($this->validatePost($mydata)) { // if no id, add the next available one if(!isset($mydata['id']) OR (int)$mydata['id'] < 1) { $this->log("No id set: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); if(count($this->data['posts']) == 0) { $mydata['id'] = 1; $this->log("Setting id to 1: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } else { $mydata['id'] = max(array_keys($this->data['posts']))+1; $this->log("Found max id and added 1 [".$mydata['id']."]: ".DataRepository::DATAFILE." (".__FUNCTION__.":".__LINE__.")"); } } // set created date if null if(!isset($mydata['created_at'])) { $mydata['created_at'] = date ("Y-m-d H:i:s", time()); } // update modified time $mydata['modified_at'] = date ("Y-m-d H:i:s", time()); // copy into data and save $this->data['posts'][$mydata['id']] = $mydata; $this->log("Before data save: (".__FUNCTION__.":".__LINE__.")", $this->data); $this->writeTheData(); } return TRUE; } public function getAllPosts() { return $this->loadPostsUsers($this->data['posts']); } public function loadPostsUsers($posts) { foreach($posts AS $id => $post) { $posts[$id]['user'] = $this->getUserById($post['user_id']); } return $posts; } public function dump($line_number, $temp = 'NO') { // if(DataRepository::$debug) { if($temp == 'NO') { $temp = $this->data; } echo "<pre>Dumping from line: $line_number\n"; echo json_encode($temp, JSON_PRETTY_PRINT); echo "</pre>"; } } } /* * Change Log * * 1.0.0 * - first version * 1.0.1 * - Added isEmailUnique() function for form validation and precheck on user save * 1.0.2 * - Fixed getAllPosts() to include the post's user info * - Added loadPostsUsers() to load one or more posts with their user info * 1.0.3 * - Added autoload to always add admin Joe. */

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  • How can I bind the second argument in a function but not the first (in an elegant way)?

    - by Frank Osterfeld
    Is there a way in Haskell to bind the second argument but not the first of a function without using lambda functions or defining another "local" function? Example. I have a binary function like: sub :: Int -> Int -> Int sub x y = x - y Now if I want to bind the first argument, I can do so easily using (sub someExpression): mapSubFrom5 x = map (sub 5) x *Main> mapSubFrom5 [1,2,3,4,5] [4,3,2,1,0] That works fine if I want to bind the first n arguments without "gap". If I want to bind the second argument but not the first, the two options I am aware of are more verbose: Either via another, local, function: mapSub5 x = map sub5 x where sub5 x = sub x 5 *Main> mapSub5 [1,2,3,4,5] [-4,-3,-2,-1,0] Or using lambda: mapSub5 x = map (\x -> sub x 5) x While both are working fine, I like the elegance of "sub 5" and wonder if there is a similarly elegant way to bind the n-th (n 1) argument of a function?

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  • How can I get returned value from JavaScript function that contain jQuery.get() ?

    - by Space Cracker
    I have a JavaScript method that call JQuery.get() and i want to return value from itto callee function .. the following is the code : function CheckExistance(userName) { $.get( "JQueryPage.aspx", { name: userName }, function(result) { if (result == "1") { value = true; } else if (result == "0") { value = false; } else if (result == "error") { value = false; } } ); return value; } i want return value; return the value setted in get() function ... i know that get() is asynchronous operation anf i want a solution to do that ?

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  • Which function should i use for testin if a var isset or not?

    - by streetparade
    I'm sometimes confused to using which one of them, say i have a function called getmember($id) function getmember($id) { // now this is the confusing part // how do i test if a $id was set or not set? //solution 1 if(empty($id)) { return false; } // solution 2 if(isset($id)) { return false; } } Thats sometimes not clear tome some times if a parameter in a function is set like function($var="") Then i do if($var ==="") { return false; } What should i use the next time isset ? emtyp ? or ===''

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  • Accessing current class through $this-> from a function called statically. [PHP]

    - by MQA
    This feels a bit messy, but I'd like to be able to call a member function statically, yet have the rest of the class behave normally... Example: <?php class Email { private $username = 'user'; private $password = 'password'; private $from = '[email protected]'; public $to; public function SendMsg($to, $body) { if (isset($this)) $email &= $this; else $email = new Email(); $email->to = $to; // Rest of function... } } Email::SendMsg('[email protected]'); How best do I allow the static function call in this example? Thanks!

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  • MySQL Syslog Audit Plugin

    - by jonathonc
    This post shows the construction process of the Syslog Audit plugin that was presented at MySQL Connect 2012. It is based on an environment that has the appropriate development tools enabled including gcc,g++ and cmake. It also assumes you have downloaded the MySQL source code (5.5.16 or higher) and have compiled and installed the system into the /usr/local/mysql directory ready for use.  The information provided below is designed to show the different components that make up a plugin, and specifically an audit type plugin, and how it comes together to be used within the MySQL service. The MySQL Reference Manual contains information regarding the plugin API and how it can be used, so please refer there for more detailed information. The code in this post is designed to give the simplest information necessary, so handling every return code, managing race conditions etc is not part of this example code. Let's start by looking at the most basic implementation of our plugin code as seen below: /*    Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.    Author:  Jonathon Coombes    Licence: GPL    Description: An auditing plugin that logs to syslog and                 can adjust the loglevel via the system variables. */ #include <stdio.h> #include <string.h> #include <mysql/plugin_audit.h> #include <syslog.h> There is a commented header detailing copyright/licencing and meta-data information and then the include headers. The two important include statements for our plugin are the syslog.h plugin, which gives us the structures for syslog, and the plugin_audit.h include which has details regarding the audit specific plugin api. Note that we do not need to include the general plugin header plugin.h, as this is done within the plugin_audit.h file already. To implement our plugin within the current implementation we need to add it into our source code and compile. > cd /usr/local/src/mysql-5.5.28/plugin > mkdir audit_syslog > cd audit_syslog A simple CMakeLists.txt file is created to manage the plugin compilation: MYSQL_ADD_PLUGIN(audit_syslog audit_syslog.cc MODULE_ONLY) Run the cmake  command at the top level of the source and then you can compile the plugin using the 'make' command. This results in a compiled audit_syslog.so library, but currently it is not much use to MySQL as there is no level of api defined to communicate with the MySQL service. Now we need to define the general plugin structure that enables MySQL to recognise the library as a plugin and be able to install/uninstall it and have it show up in the system. The structure is defined in the plugin.h file in the MySQL source code.  /*   Plugin library descriptor */ mysql_declare_plugin(audit_syslog) {   MYSQL_AUDIT_PLUGIN,           /* plugin type                    */   &audit_syslog_descriptor,     /* descriptor handle               */   "audit_syslog",               /* plugin name                     */   "Author Name",                /* author                          */   "Simple Syslog Audit",        /* description                     */   PLUGIN_LICENSE_GPL,           /* licence                         */   audit_syslog_init,            /* init function     */   audit_syslog_deinit,          /* deinit function */   0x0001,                       /* plugin version                  */   NULL,                         /* status variables        */   NULL,                         /* system variables                */   NULL,                         /* no reserves                     */   0,                            /* no flags                        */ } mysql_declare_plugin_end; The general plugin descriptor above is standard for all plugin types in MySQL. The plugin type is defined along with the init/deinit functions and interface methods into the system for sharing information, and various other metadata information. The descriptors have an internally recognised version number so that plugins can be matched against the api on the running server. The other details are usually related to the type-specific methods and structures to implement the plugin. Each plugin has a type-specific descriptor as well which details how the plugin is implemented for the specific purpose of that plugin type. /*   Plugin type-specific descriptor */ static struct st_mysql_audit audit_syslog_descriptor= {   MYSQL_AUDIT_INTERFACE_VERSION,                        /* interface version    */   NULL,                                                 /* release_thd function */   audit_syslog_notify,                                  /* notify function      */   { (unsigned long) MYSQL_AUDIT_GENERAL_CLASSMASK |                     MYSQL_AUDIT_CONNECTION_CLASSMASK }  /* class mask           */ }; In this particular case, the release_thd function has not been defined as it is not required. The important method for auditing is the notify function which is activated when an event occurs on the system. The notify function is designed to activate on an event and the implementation will determine how it is handled. For the audit_syslog plugin, the use of the syslog feature sends all events to the syslog for recording. The class mask allows us to determine what type of events are being seen by the notify function. There are currently two major types of event: 1. General Events: This includes general logging, errors, status and result type events. This is the main one for tracking the queries and operations on the database. 2. Connection Events: This group is based around user logins. It monitors connections and disconnections, but also if somebody changes user while connected. With most audit plugins, the principle behind the plugin is to track changes to the system over time and counters can be an important part of this process. The next step is to define and initialise the counters that are used to track the events in the service. There are 3 counters defined in total for our plugin - the # of general events, the # of connection events and the total number of events.  static volatile int total_number_of_calls; /* Count MYSQL_AUDIT_GENERAL_CLASS event instances */ static volatile int number_of_calls_general; /* Count MYSQL_AUDIT_CONNECTION_CLASS event instances */ static volatile int number_of_calls_connection; The init and deinit functions for the plugin are there to be called when the plugin is activated and when it is terminated. These offer the best option to initialise the counters for our plugin: /*  Initialize the plugin at server start or plugin installation. */ static int audit_syslog_init(void *arg __attribute__((unused))) {     openlog("mysql_audit:",LOG_PID|LOG_PERROR|LOG_CONS,LOG_USER);     total_number_of_calls= 0;     number_of_calls_general= 0;     number_of_calls_connection= 0;     return(0); } The init function does a call to openlog to initialise the syslog functionality. The parameters are the service to log under ("mysql_audit" in this case), the syslog flags and the facility for the logging. Then each of the counters are initialised to zero and a success is returned. If the init function is not defined, it will return success by default. /*  Terminate the plugin at server shutdown or plugin deinstallation. */ static int audit_syslog_deinit(void *arg __attribute__((unused))) {     closelog();     return(0); } The deinit function will simply close our syslog connection and return success. Note that the syslog functionality is part of the glibc libraries and does not require any external factors.  The function names are what we define in the general plugin structure, so these have to match otherwise there will be errors. The next step is to implement the event notifier function that was defined in the type specific descriptor (audit_syslog_descriptor) which is audit_syslog_notify. /* Event notifier function */ static void audit_syslog_notify(MYSQL_THD thd __attribute__((unused)), unsigned int event_class, const void *event) { total_number_of_calls++; if (event_class == MYSQL_AUDIT_GENERAL_CLASS) { const struct mysql_event_general *event_general= (const struct mysql_event_general *) event; number_of_calls_general++; syslog(audit_loglevel,"%lu: User: %s Command: %s Query: %s\n", event_general->general_thread_id, event_general->general_user, event_general->general_command, event_general->general_query ); } else if (event_class == MYSQL_AUDIT_CONNECTION_CLASS) { const struct mysql_event_connection *event_connection= (const struct mysql_event_connection *) event; number_of_calls_connection++; syslog(audit_loglevel,"%lu: User: %s@%s[%s] Event: %d Status: %d\n", event_connection->thread_id, event_connection->user, event_connection->host, event_connection->ip, event_connection->event_subclass, event_connection->status ); } }   In the case of an event, the notifier function is called. The first step is to increment the total number of events that have occurred in our database.The event argument is then cast into the appropriate event structure depending on the class type, of general event or connection event. The event type counters are incremented and details are sent via the syslog() function out to the system log. There are going to be different line formats and information returned since the general events have different data compared to the connection events, even though some of the details overlap, for example, user, thread id, host etc. On compiling the code now, there should be no errors and the resulting audit_syslog.so can be loaded into the server and ready to use. Log into the server and type: mysql> INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so'; This will install the plugin and will start updating the syslog immediately. Note that the audit plugin attaches to the immediate thread and cannot be uninstalled while that thread is active. This means that you cannot run the UNISTALL command until you log into a different connection (thread) on the server. Once the plugin is loaded, the system log will show output such as the following: Oct  8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct  8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct  8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: show tables Oct  8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: show tables Oct  8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: select * from t1 Oct  8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: select * from t1 It appears that two of each event is being shown, but in actuality, these are two separate event types - the result event and the status event. This could be refined further by changing the audit_syslog_notify function to handle the different event sub-types in a different manner.  So far, it seems that the logging is working with events showing up in the syslog output. The issue now is that the counters created earlier to track the number of events by type are not accessible when the plugin is being run. Instead there needs to be a way to expose the plugin specific information to the service and vice versa. This could be done via the information_schema plugin api, but for something as simple as counters, the obvious choice is the system status variables. This is done using the standard structure and the declaration: /*  Plugin status variables for SHOW STATUS */ static struct st_mysql_show_var audit_syslog_status[]= {   { "Audit_syslog_total_calls",     (char *) &total_number_of_calls,     SHOW_INT },   { "Audit_syslog_general_events",     (char *) &number_of_calls_general,     SHOW_INT },   { "Audit_syslog_connection_events",     (char *) &number_of_calls_connection,     SHOW_INT },   { 0, 0, SHOW_INT } };   The structure is simply the name that will be displaying in the mysql service, the address of the associated variables, and the data type being used for the counter. It is finished with a blank structure to show that there are no more variables. Remember that status variables may have the same name for variables from other plugin, so it is considered appropriate to add the plugin name at the start of the status variable name to avoid confusion. Looking at the status variables in the mysql client shows something like the following: mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name                  | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1     | | Audit_syslog_general_events    | 2     | | Audit_syslog_total_calls       | 3     | +--------------------------------+-------+ 3 rows in set (0.00 sec) The final connectivity piece for the plugin is to allow the interactive change of the logging level between the plugin and the system. This requires the ability to send changes via the mysql service through to the plugin. This is done using the system variables interface and defining a single variable to keep track of the active logging level for the facility. /* Plugin system variables for SHOW VARIABLES */ static MYSQL_SYSVAR_STR(loglevel, audit_loglevel,                         PLUGIN_VAR_RQCMDARG,                         "User can specify the log level for auditing",                         audit_loglevel_check, audit_loglevel_update, "LOG_NOTICE"); static struct st_mysql_sys_var* audit_syslog_sysvars[] = {     MYSQL_SYSVAR(loglevel),     NULL }; So now the system variable 'loglevel' is defined for the plugin and associated to the global variable 'audit_loglevel'. The check or validation function is defined to make sure that no garbage values are attempted in the update of the variable. The update function is used to save the new value to the variable. Note that the audit_syslog_sysvars structure is defined in the general plugin descriptor to associate the link between the plugin and the system and how much they interact. Next comes the implementation of the validation function and the update function for the system variable. It is worth noting that if you have a simple numeric such as integers for the variable types, the validate function is often not required as MySQL will handle the automatic check and validation of simple types. /* longest valid value */ #define MAX_LOGLEVEL_SIZE 100 /* hold the valid values */ static const char *possible_modes[]= { "LOG_ERROR", "LOG_WARNING", "LOG_NOTICE", NULL };  static int audit_loglevel_check(     THD*                        thd,    /*!< in: thread handle */     struct st_mysql_sys_var*    var,    /*!< in: pointer to system                                         variable */     void*                       save,   /*!< out: immediate result                                         for update function */     struct st_mysql_value*      value)  /*!< in: incoming string */ {     char buff[MAX_LOGLEVEL_SIZE];     const char *str;     const char **found;     int length;     length= sizeof(buff);     if (!(str= value->val_str(value, buff, &length)))         return 1;     /*         We need to return a pointer to a locally allocated value in "save".         Here we pick to search for the supplied value in an global array of         constant strings and return a pointer to one of them.         The other possiblity is to use the thd_alloc() function to allocate         a thread local buffer instead of the global constants.     */     for (found= possible_modes; *found; found++)     {         if (!strcmp(*found, str))         {             *(const char**)save= *found;             return 0;         }     }     return 1; } The validation function is simply to take the value being passed in via the SET GLOBAL VARIABLE command and check if it is one of the pre-defined values allowed  in our possible_values array. If it is found to be valid, then the value is assigned to the save variable ready for passing through to the update function. static void audit_loglevel_update(     THD*                        thd,        /*!< in: thread handle */     struct st_mysql_sys_var*    var,        /*!< in: system variable                                             being altered */     void*                       var_ptr,    /*!< out: pointer to                                             dynamic variable */     const void*                 save)       /*!< in: pointer to                                             temporary storage */ {     /* assign the new value so that the server can read it */     *(char **) var_ptr= *(char **) save;     /* assign the new value to the internal variable */     audit_loglevel= *(char **) save; } Since all the validation has been done already, the update function is quite simple for this plugin. The first part is to update the system variable pointer so that the server can read the value. The second part is to update our own global plugin variable for tracking the value. Notice that the save variable is passed in as a void type to allow handling of various data types, so it must be cast to the appropriate data type when assigning it to the variables. Looking at how the latest changes affect the usage of the plugin and the interaction within the server shows: mysql> show global variables like "audit%"; +-----------------------+------------+ | Variable_name         | Value      | +-----------------------+------------+ | audit_syslog_loglevel | LOG_NOTICE | +-----------------------+------------+ 1 row in set (0.00 sec) mysql> set global audit_syslog_loglevel="LOG_ERROR"; Query OK, 0 rows affected (0.00 sec) mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name                  | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1     | | Audit_syslog_general_events    | 11    | | Audit_syslog_total_calls       | 12    | +--------------------------------+-------+ 3 rows in set (0.00 sec) mysql> show global variables like "audit%"; +-----------------------+-----------+ | Variable_name         | Value     | +-----------------------+-----------+ | audit_syslog_loglevel | LOG_ERROR | +-----------------------+-----------+ 1 row in set (0.00 sec)   So now we have a plugin that will audit the events on the system and log the details to the system log. It allows for interaction to see the number of different events within the server details and provides a mechanism to change the logging level interactively via the standard system methods of the SET command. A more complex auditing plugin may have more detailed code, but each of the above areas is what will be involved and simply expanded on to add more functionality. With the above skeleton code, it is now possible to create your own audit plugins to implement your own auditing requirements. If, however, you are not of the coding persuasion, then you could always consider the option of the MySQL Enterprise Audit plugin that is available to purchase.

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  • Adding Unobtrusive Validation To MVCContrib Fluent Html

    - by srkirkland
    ASP.NET MVC 3 includes a new unobtrusive validation strategy that utilizes HTML5 data-* attributes to decorate form elements.  Using a combination of jQuery validation and an unobtrusive validation adapter script that comes with MVC 3, those attributes are then turned into client side validation rules. A Quick Introduction to Unobtrusive Validation To quickly show how this works in practice, assume you have the following Order.cs class (think Northwind) [If you are familiar with unobtrusive validation in MVC 3 you can skip to the next section]: public class Order : DomainObject { [DataType(DataType.Date)] public virtual DateTime OrderDate { get; set; }   [Required] [StringLength(12)] public virtual string ShipAddress { get; set; }   [Required] public virtual Customer OrderedBy { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Note the System.ComponentModel.DataAnnotations attributes, which provide the validation and metadata information used by ASP.NET MVC 3 to determine how to render out these properties.  Now let’s assume we have a form which can edit this Order class, specifically let’s look at the ShipAddress property: @Html.LabelFor(x => x.Order.ShipAddress) @Html.EditorFor(x => x.Order.ShipAddress) @Html.ValidationMessageFor(x => x.Order.ShipAddress) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now the Html.EditorFor() method is smart enough to look at the ShipAddress attributes and write out the necessary unobtrusive validation html attributes.  Note we could have used Html.TextBoxFor() or even Html.TextBox() and still retained the same results. If we view source on the input box generated by the Html.EditorFor() call, we get the following: <input type="text" value="Rua do Paço, 67" name="Order.ShipAddress" id="Order_ShipAddress" data-val-required="The ShipAddress field is required." data-val-length-max="12" data-val-length="The field ShipAddress must be a string with a maximum length of 12." data-val="true" class="text-box single-line input-validation-error"> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } As you can see, we have data-val-* attributes for both required and length, along with the proper error messages and additional data as necessary (in this case, we have the length-max=”12”). And of course, if we try to submit the form with an invalid value, we get an error on the client: Working with MvcContrib’s Fluent Html The MvcContrib project offers a fluent interface for creating Html elements which I find very expressive and useful, especially when it comes to creating select lists.  Let’s look at a few quick examples: @this.TextBox(x => x.FirstName).Class("required").Label("First Name:") @this.MultiSelect(x => x.UserId).Options(ViewModel.Users) @this.CheckBox("enabled").LabelAfter("Enabled").Title("Click to enable.").Styles(vertical_align => "middle")   @(this.Select("Order.OrderedBy").Options(Model.Customers, x => x.Id, x => x.CompanyName) .Selected(Model.Order.OrderedBy != null ? Model.Order.OrderedBy.Id : "") .FirstOption(null, "--Select A Company--") .HideFirstOptionWhen(Model.Order.OrderedBy != null) .Label("Ordered By:")) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } These fluent html helpers create the normal html you would expect, and I think they make life a lot easier and more readable when dealing with complex markup or select list data models (look ma: no anonymous objects for creating class names!). Of course, the problem we have now is that MvcContrib’s fluent html helpers don’t know about ASP.NET MVC 3’s unobtrusive validation attributes and thus don’t take part in client validation on your page.  This is not ideal, so I wrote a quick helper method to extend fluent html with the knowledge of what unobtrusive validation attributes to include when they are rendered. Extending MvcContrib’s Fluent Html Before posting the code, there are just a few things you need to know.  The first is that all Fluent Html elements implement the IElement interface (MvcContrib.FluentHtml.Elements.IElement), and the second is that the base System.Web.Mvc.HtmlHelper has been extended with a method called GetUnobtrusiveValidationAttributes which we can use to determine the necessary attributes to include.  With this knowledge we can make quick work of extending fluent html: public static class FluentHtmlExtensions { public static T IncludeUnobtrusiveValidationAttributes<T>(this T element, HtmlHelper htmlHelper) where T : MvcContrib.FluentHtml.Elements.IElement { IDictionary<string, object> validationAttributes = htmlHelper .GetUnobtrusiveValidationAttributes(element.GetAttr("name"));   foreach (var validationAttribute in validationAttributes) { element.SetAttr(validationAttribute.Key, validationAttribute.Value); }   return element; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The code is pretty straight forward – basically we use a passed HtmlHelper to get a list of validation attributes for the current element and then add each of the returned attributes to the element to be rendered. The Extension In Action Now let’s get back to the earlier ShipAddress example and see what we’ve accomplished.  First we will use a fluent html helper to render out the ship address text input (this is the ‘before’ case): @this.TextBox("Order.ShipAddress").Label("Ship Address:").Class("class-name") .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } And the resulting HTML: <label id="Order_ShipAddress_Label" for="Order_ShipAddress">Ship Address:</label> <input type="text" value="Rua do Paço, 67" name="Order.ShipAddress" id="Order_ShipAddress" class="class-name"> Now let’s do the same thing except here we’ll use the newly written extension method: @this.TextBox("Order.ShipAddress").Label("Ship Address:") .Class("class-name").IncludeUnobtrusiveValidationAttributes(Html) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } And the resulting HTML: <label id="Order_ShipAddress_Label" for="Order_ShipAddress">Ship Address:</label> <input type="text" value="Rua do Paço, 67" name="Order.ShipAddress" id="Order_ShipAddress" data-val-required="The ShipAddress field is required." data-val-length-max="12" data-val-length="The field ShipAddress must be a string with a maximum length of 12." data-val="true" class="class-name"> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Excellent!  Now we can continue to use unobtrusive validation and have the flexibility to use ASP.NET MVC’s Html helpers or MvcContrib’s fluent html helpers interchangeably, and every element will participate in client side validation. Wrap Up Overall I’m happy with this solution, although in the best case scenario MvcContrib would know about unobtrusive validation attributes and include them automatically (of course if it is enabled in the web.config file).  I know that MvcContrib allows you to author global behaviors, but that requires changing the base class of your views, which I am not willing to do. Enjoy!

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  • Introducing Data Annotations Extensions

    - by srkirkland
    Validation of user input is integral to building a modern web application, and ASP.NET MVC offers us a way to enforce business rules on both the client and server using Model Validation.  The recent release of ASP.NET MVC 3 has improved these offerings on the client side by introducing an unobtrusive validation library built on top of jquery.validation.  Out of the box MVC comes with support for Data Annotations (that is, System.ComponentModel.DataAnnotations) and can be extended to support other frameworks.  Data Annotations Validation is becoming more popular and is being baked in to many other Microsoft offerings, including Entity Framework, though with MVC it only contains four validators: Range, Required, StringLength and Regular Expression.  The Data Annotations Extensions project attempts to augment these validators with additional attributes while maintaining the clean integration Data Annotations provides. A Quick Word About Data Annotations Extensions The Data Annotations Extensions project can be found at http://dataannotationsextensions.org/, and currently provides 11 additional validation attributes (ex: Email, EqualTo, Min/Max) on top of Data Annotations’ original 4.  You can find a current list of the validation attributes on the afore mentioned website. The core library provides server-side validation attributes that can be used in any .NET 4.0 project (no MVC dependency). There is also an easily pluggable client-side validation library which can be used in ASP.NET MVC 3 projects using unobtrusive jquery validation (only MVC3 included javascript files are required). On to the Preview Let’s say you had the following “Customer” domain model (or view model, depending on your project structure) in an MVC 3 project: public class Customer { public string Email { get; set; } public int Age { get; set; } public string ProfilePictureLocation { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } When it comes time to create/edit this Customer, you will probably have a CustomerController and a simple form that just uses one of the Html.EditorFor() methods that the ASP.NET MVC tooling generates for you (or you can write yourself).  It should look something like this: With no validation, the customer can enter nonsense for an email address, and then can even report their age as a negative number!  With the built-in Data Annotations validation, I could do a bit better by adding a Range to the age, adding a RegularExpression for email (yuck!), and adding some required attributes.  However, I’d still be able to report my age as 10.75 years old, and my profile picture could still be any string.  Let’s use Data Annotations along with this project, Data Annotations Extensions, and see what we can get: public class Customer { [Email] [Required] public string Email { get; set; }   [Integer] [Min(1, ErrorMessage="Unless you are benjamin button you are lying.")] [Required] public int Age { get; set; }   [FileExtensions("png|jpg|jpeg|gif")] public string ProfilePictureLocation { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now let’s try to put in some invalid values and see what happens: That is very nice validation, all done on the client side (will also be validated on the server).  Also, the Customer class validation attributes are very easy to read and understand. Another bonus: Since Data Annotations Extensions can integrate with MVC 3’s unobtrusive validation, no additional scripts are required! Now that we’ve seen our target, let’s take a look at how to get there within a new MVC 3 project. Adding Data Annotations Extensions To Your Project First we will File->New Project and create an ASP.NET MVC 3 project.  I am going to use Razor for these examples, but any view engine can be used in practice.  Now go into the NuGet Extension Manager (right click on references and select add Library Package Reference) and search for “DataAnnotationsExtensions.”  You should see the following two packages: The first package is for server-side validation scenarios, but since we are using MVC 3 and would like comprehensive sever and client validation support, click on the DataAnnotationsExtensions.MVC3 project and then click Install.  This will install the Data Annotations Extensions server and client validation DLLs along with David Ebbo’s web activator (which enables the validation attributes to be registered with MVC 3). Now that Data Annotations Extensions is installed you have all you need to start doing advanced model validation.  If you are already using Data Annotations in your project, just making use of the additional validation attributes will provide client and server validation automatically.  However, assuming you are starting with a blank project I’ll walk you through setting up a controller and model to test with. Creating Your Model In the Models folder, create a new User.cs file with a User class that you can use as a model.  To start with, I’ll use the following class: public class User { public string Email { get; set; } public string Password { get; set; } public string PasswordConfirm { get; set; } public string HomePage { get; set; } public int Age { get; set; } } Next, create a simple controller with at least a Create method, and then a matching Create view (note, you can do all of this via the MVC built-in tooling).  Your files will look something like this: UserController.cs: public class UserController : Controller { public ActionResult Create() { return View(new User()); }   [HttpPost] public ActionResult Create(User user) { if (!ModelState.IsValid) { return View(user); }   return Content("User valid!"); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Create.cshtml: @model NuGetValidationTester.Models.User   @{ ViewBag.Title = "Create"; }   <h2>Create</h2>   <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>   @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>User</legend> @Html.EditorForModel() <p> <input type="submit" value="Create" /> </p> </fieldset> } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } In the Create.cshtml view, note that we are referencing jquery validation and jquery unobtrusive (jquery is referenced in the layout page).  These MVC 3 included scripts are the only ones you need to enjoy both the basic Data Annotations validation as well as the validation additions available in Data Annotations Extensions.  These references are added by default when you use the MVC 3 “Add View” dialog on a modification template type. Now when we go to /User/Create we should see a form for editing a User Since we haven’t yet added any validation attributes, this form is valid as shown (including no password, email and an age of 0).  With the built-in Data Annotations attributes we can make some of the fields required, and we could use a range validator of maybe 1 to 110 on Age (of course we don’t want to leave out supercentenarians) but let’s go further and validate our input comprehensively using Data Annotations Extensions.  The new and improved User.cs model class. { [Required] [Email] public string Email { get; set; }   [Required] public string Password { get; set; }   [Required] [EqualTo("Password")] public string PasswordConfirm { get; set; }   [Url] public string HomePage { get; set; }   [Integer] [Min(1)] public int Age { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now let’s re-run our form and try to use some invalid values: All of the validation errors you see above occurred on the client, without ever even hitting submit.  The validation is also checked on the server, which is a good practice since client validation is easily bypassed. That’s all you need to do to start a new project and include Data Annotations Extensions, and of course you can integrate it into an existing project just as easily. Nitpickers Corner ASP.NET MVC 3 futures defines four new data annotations attributes which this project has as well: CreditCard, Email, Url and EqualTo.  Unfortunately referencing MVC 3 futures necessitates taking an dependency on MVC 3 in your model layer, which may be unadvisable in a multi-tiered project.  Data Annotations Extensions keeps the server and client side libraries separate so using the project’s validation attributes don’t require you to take any additional dependencies in your model layer which still allowing for the rich client validation experience if you are using MVC 3. Custom Error Message and Globalization: Since the Data Annotations Extensions are build on top of Data Annotations, you have the ability to define your own static error messages and even to use resource files for very customizable error messages. Available Validators: Please see the project site at http://dataannotationsextensions.org/ for an up-to-date list of the new validators included in this project.  As of this post, the following validators are available: CreditCard Date Digits Email EqualTo FileExtensions Integer Max Min Numeric Url Conclusion Hopefully I’ve illustrated how easy it is to add server and client validation to your MVC 3 projects, and how to easily you can extend the available validation options to meet real world needs. The Data Annotations Extensions project is fully open source under the BSD license.  Any feedback would be greatly appreciated.  More information than you require, along with links to the source code, is available at http://dataannotationsextensions.org/. Enjoy!

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  • Using Stub Objects

    - by user9154181
    Having told the long and winding tale of where stub objects came from and how we use them to build Solaris, I'd like to focus now on the the nuts and bolts of building and using them. The following new features were added to the Solaris link-editor (ld) to support the production and use of stub objects: -z stub This new command line option informs ld that it is to build a stub object rather than a normal object. In this mode, it accepts the same command line arguments as usual, but will quietly ignore any objects and sharable object dependencies. STUB_OBJECT Mapfile Directive In order to build a stub version of an object, its mapfile must specify the STUB_OBJECT directive. When producing a non-stub object, the presence of STUB_OBJECT causes the link-editor to perform extra validation to ensure that the stub and non-stub objects will be compatible. ASSERT Mapfile Directive All data symbols exported from the object must have an ASSERT symbol directive in the mapfile that declares them as data and supplies the size, binding, bss attributes, and symbol aliasing details. When building the stub objects, the information in these ASSERT directives is used to create the data symbols. When building the real object, these ASSERT directives will ensure that the real object matches the linking interface presented by the stub. Although ASSERT was added to the link-editor in order to support stub objects, they are a general purpose feature that can be used independently of stub objects. For instance you might choose to use an ASSERT directive if you have a symbol that must have a specific address in order for the object to operate properly and you want to automatically ensure that this will always be the case. The material presented here is derived from a document I originally wrote during the development effort, which had the dual goals of providing supplemental materials for the stub object PSARC case, and as a set of edits that were eventually applied to the Oracle Solaris Linker and Libraries Manual (LLM). The Solaris 11 LLM contains this information in a more polished form. Stub Objects A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be used at runtime. However, an application can be built against a stub object, where the stub object provides the real object name to be used at runtime, and then use the real object at runtime. When building a stub object, the link-editor ignores any object or library files specified on the command line, and these files need not exist in order to build a stub. Since the compilation step can be omitted, and because the link-editor has relatively little work to do, stub objects can be built very quickly. Stub objects can be used to solve a variety of build problems: Speed Modern machines, using a version of make with the ability to parallelize operations, are capable of compiling and linking many objects simultaneously, and doing so offers significant speedups. However, it is typical that a given object will depend on other objects, and that there will be a core set of objects that nearly everything else depends on. It is necessary to impose an ordering that builds each object before any other object that requires it. This ordering creates bottlenecks that reduce the amount of parallelization that is possible and limits the overall speed at which the code can be built. Complexity/Correctness In a large body of code, there can be a large number of dependencies between the various objects. The makefiles or other build descriptions for these objects can become very complex and difficult to understand or maintain. The dependencies can change as the system evolves. This can cause a given set of makefiles to become slightly incorrect over time, leading to race conditions and mysterious rare build failures. Dependency Cycles It might be desirable to organize code as cooperating shared objects, each of which draw on the resources provided by the other. Such cycles cannot be supported in an environment where objects must be built before the objects that use them, even though the runtime linker is fully capable of loading and using such objects if they could be built. Stub shared objects offer an alternative method for building code that sidesteps the above issues. Stub objects can be quickly built for all the shared objects produced by the build. Then, all the real shared objects and executables can be built in parallel, in any order, using the stub objects to stand in for the real objects at link-time. Afterwards, the executables and real shared objects are kept, and the stub shared objects are discarded. Stub objects are built from a mapfile, which must satisfy the following requirements. The mapfile must specify the STUB_OBJECT directive. This directive informs the link-editor that the object can be built as a stub object, and as such causes the link-editor to perform validation and sanity checking intended to guarantee that an object and its stub will always provide identical linking interfaces. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data exported from the object must have an ASSERT symbol attribute in the mapfile to specify the symbol type, size, and bss attributes. In the case where there are multiple symbols that reference the same data, the ASSERT for one of these symbols must specify the TYPE and SIZE attributes, while the others must use the ALIAS attribute to reference this primary symbol. Given such a mapfile, the stub and real versions of the shared object can be built using the same command line for each, adding the '-z stub' option to the link for the stub object, and omiting the option from the link for the real object. To demonstrate these ideas, the following code implements a shared object named idx5, which exports data from a 5 element array of integers, with each element initialized to contain its zero-based array index. This data is available as a global array, via an alternative alias data symbol with weak binding, and via a functional interface. % cat idx5.c int _idx5[5] = { 0, 1, 2, 3, 4 }; #pragma weak idx5 = _idx5 int idx5_func(int index) { if ((index 4)) return (-1); return (_idx5[index]); } A mapfile is required to describe the interface provided by this shared object. % cat mapfile $mapfile_version 2 STUB_OBJECT; SYMBOL_SCOPE { _idx5 { ASSERT { TYPE=data; SIZE=4[5] }; }; idx5 { ASSERT { BINDING=weak; ALIAS=_idx5 }; }; idx5_func; local: *; }; The following main program is used to print all the index values available from the idx5 shared object. % cat main.c #include <stdio.h> extern int _idx5[5], idx5[5], idx5_func(int); int main(int argc, char **argv) { int i; for (i = 0; i The following commands create a stub version of this shared object in a subdirectory named stublib. elfdump is used to verify that the resulting object is a stub. The command used to build the stub differs from that of the real object only in the addition of the -z stub option, and the use of a different output file name. This demonstrates the ease with which stub generation can be added to an existing makefile. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o stublib/libidx5.so.1 -zstub % ln -s libidx5.so.1 stublib/libidx5.so % elfdump -d stublib/libidx5.so | grep STUB [11] FLAGS_1 0x4000000 [ STUB ] The main program can now be built, using the stub object to stand in for the real shared object, and setting a runpath that will find the real object at runtime. However, as we have not yet built the real object, this program cannot yet be run. Attempts to cause the system to load the stub object are rejected, as the runtime linker knows that stub objects lack the actual code and data found in the real object, and cannot execute. % cc main.c -L stublib -R '$ORIGIN/lib' -lidx5 -lc % ./a.out ld.so.1: a.out: fatal: libidx5.so.1: open failed: No such file or directory Killed % LD_PRELOAD=stublib/libidx5.so.1 ./a.out ld.so.1: a.out: fatal: stublib/libidx5.so.1: stub shared object cannot be used at runtime Killed We build the real object using the same command as we used to build the stub, omitting the -z stub option, and writing the results to a different file. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o lib/libidx5.so.1 Once the real object has been built in the lib subdirectory, the program can be run. % ./a.out [0] 0 0 0 [1] 1 1 1 [2] 2 2 2 [3] 3 3 3 [4] 4 4 4 Mapfile Changes The version 2 mapfile syntax was extended in a number of places to accommodate stub objects. Conditional Input The version 2 mapfile syntax has the ability conditionalize mapfile input using the $if control directive. As you might imagine, these directives are used frequently with ASSERT directives for data, because a given data symbol will frequently have a different size in 32 or 64-bit code, or on differing hardware such as x86 versus sparc. The link-editor maintains an internal table of names that can be used in the logical expressions evaluated by $if and $elif. At startup, this table is initialized with items that describe the class of object (_ELF32 or _ELF64) and the type of the target machine (_sparc or _x86). We found that there were a small number of cases in the Solaris code base in which we needed to know what kind of object we were producing, so we added the following new predefined items in order to address that need: NameMeaning ...... _ET_DYNshared object _ET_EXECexecutable object _ET_RELrelocatable object ...... STUB_OBJECT Directive The new STUB_OBJECT directive informs the link-editor that the object described by the mapfile can be built as a stub object. STUB_OBJECT; A stub shared object is built entirely from the information in the mapfiles supplied on the command line. When the -z stub option is specified to build a stub object, the presence of the STUB_OBJECT directive in a mapfile is required, and the link-editor uses the information in symbol ASSERT attributes to create global symbols that match those of the real object. When the real object is built, the presence of STUB_OBJECT causes the link-editor to verify that the mapfiles accurately describe the real object interface, and that a stub object built from them will provide the same linking interface as the real object it represents. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data in the object is required to have an ASSERT attribute that specifies the symbol type and size. If the ASSERT BIND attribute is not present, the link-editor provides a default assertion that the symbol must be GLOBAL. If the ASSERT SH_ATTR attribute is not present, or does not specify that the section is one of BITS or NOBITS, the link-editor provides a default assertion that the associated section is BITS. All data symbols that describe the same address and size are required to have ASSERT ALIAS attributes specified in the mapfile. If aliased symbols are discovered that do not have an ASSERT ALIAS specified, the link fails and no object is produced. These rules ensure that the mapfiles contain a description of the real shared object's linking interface that is sufficient to produce a stub object with a completely compatible linking interface. SYMBOL_SCOPE/SYMBOL_VERSION ASSERT Attribute The SYMBOL_SCOPE and SYMBOL_VERSION mapfile directives were extended with a symbol attribute named ASSERT. The syntax for the ASSERT attribute is as follows: ASSERT { ALIAS = symbol_name; BINDING = symbol_binding; TYPE = symbol_type; SH_ATTR = section_attributes; SIZE = size_value; SIZE = size_value[count]; }; The ASSERT attribute is used to specify the expected characteristics of the symbol. The link-editor compares the symbol characteristics that result from the link to those given by ASSERT attributes. If the real and asserted attributes do not agree, a fatal error is issued and the output object is not created. In normal use, the link editor evaluates the ASSERT attribute when present, but does not require them, or provide default values for them. The presence of the STUB_OBJECT directive in a mapfile alters the interpretation of ASSERT to require them under some circumstances, and to supply default assertions if explicit ones are not present. See the definition of the STUB_OBJECT Directive for the details. When the -z stub command line option is specified to build a stub object, the information provided by ASSERT attributes is used to define the attributes of the global symbols provided by the object. ASSERT accepts the following: ALIAS Name of a previously defined symbol that this symbol is an alias for. An alias symbol has the same type, value, and size as the main symbol. The ALIAS attribute is mutually exclusive to the TYPE, SIZE, and SH_ATTR attributes, and cannot be used with them. When ALIAS is specified, the type, size, and section attributes are obtained from the alias symbol. BIND Specifies an ELF symbol binding, which can be any of the STB_ constants defined in <sys/elf.h>, with the STB_ prefix removed (e.g. GLOBAL, WEAK). TYPE Specifies an ELF symbol type, which can be any of the STT_ constants defined in <sys/elf.h>, with the STT_ prefix removed (e.g. OBJECT, COMMON, FUNC). In addition, for compatibility with other mapfile usage, FUNCTION and DATA can be specified, for STT_FUNC and STT_OBJECT, respectively. TYPE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SH_ATTR Specifies attributes of the section associated with the symbol. The section_attributes that can be specified are given in the following table: Section AttributeMeaning BITSSection is not of type SHT_NOBITS NOBITSSection is of type SHT_NOBITS SH_ATTR is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SIZE Specifies the expected symbol size. SIZE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. The syntax for the size_value argument is as described in the discussion of the SIZE attribute below. SIZE The SIZE symbol attribute existed before support for stub objects was introduced. It is used to set the size attribute of a given symbol. This attribute results in the creation of a symbol definition. Prior to the introduction of the ASSERT SIZE attribute, the value of a SIZE attribute was always numeric. While attempting to apply ASSERT SIZE to the objects in the Solaris ON consolidation, I found that many data symbols have a size based on the natural machine wordsize for the class of object being produced. Variables declared as long, or as a pointer, will be 4 bytes in size in a 32-bit object, and 8 bytes in a 64-bit object. Initially, I employed the conditional $if directive to handle these cases as follows: $if _ELF32 foo { ASSERT { TYPE=data; SIZE=4 } }; bar { ASSERT { TYPE=data; SIZE=20 } }; $elif _ELF64 foo { ASSERT { TYPE=data; SIZE=8 } }; bar { ASSERT { TYPE=data; SIZE=40 } }; $else $error UNKNOWN ELFCLASS $endif I found that the situation occurs frequently enough that this is cumbersome. To simplify this case, I introduced the idea of the addrsize symbolic name, and of a repeat count, which together make it simple to specify machine word scalar or array symbols. Both the SIZE, and ASSERT SIZE attributes support this syntax: The size_value argument can be a numeric value, or it can be the symbolic name addrsize. addrsize represents the size of a machine word capable of holding a memory address. The link-editor substitutes the value 4 for addrsize when building 32-bit objects, and the value 8 when building 64-bit objects. addrsize is useful for representing the size of pointer variables and C variables of type long, as it automatically adjusts for 32 and 64-bit objects without requiring the use of conditional input. The size_value argument can be optionally suffixed with a count value, enclosed in square brackets. If count is present, size_value and count are multiplied together to obtain the final size value. Using this feature, the example above can be written more naturally as: foo { ASSERT { TYPE=data; SIZE=addrsize } }; bar { ASSERT { TYPE=data; SIZE=addrsize[5] } }; Exported Global Data Is Still A Bad Idea As you can see, the additional plumbing added to the Solaris link-editor to support stub objects is minimal. Furthermore, about 90% of that plumbing is dedicated to handling global data. We have long advised against global data exported from shared objects. There are many ways in which global data does not fit well with dynamic linking. Stub objects simply provide one more reason to avoid this practice. It is always better to export all data via a functional interface. You should always hide your data, and make it available to your users via a function that they can call to acquire the address of the data item. However, If you do have to support global data for a stub, perhaps because you are working with an already existing object, it is still easilily done, as shown above. Oracle does not like us to discuss hypothetical new features that don't exist in shipping product, so I'll end this section with a speculation. It might be possible to do more in this area to ease the difficulty of dealing with objects that have global data that the users of the library don't need. Perhaps someday... Conclusions It is easy to create stub objects for most objects. If your library only exports function symbols, all you have to do to build a faithful stub object is to add STUB_OBJECT; and then to use the same link command you're currently using, with the addition of the -z stub option. Happy Stubbing!

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  • How to loop through LI items in UL, get specific attributes, and pass them via $.ajax data

    - by Ahmed Fouad
    Here is my HTML code: <ul id="gallery"> <li id="attachment-32" class="featured"><a href="..." title=""><img src="..." alt="" /></a></li> <li id="attachment-34"><a href="..." title=""><img src="..." alt="" /></a></li> <li id="attachment-38"><a href="..." title=""><img src="..." alt="" /></a></li> <li id="attachment-64"><a href="..." title=""><img src="..." alt="" /></a></li> <li id="attachment-75"><a href="..." title=""><img src="..." alt="" /></a></li> <li></li> </ul> Here is my sample ajax request: $.ajax({ url: '/ajax/upload.php', type: 'POST', data: { ... }, success: function(data){ } }); Here is what I want to achieve. How to get the attachment number in ID attribute for every LI inside the gallery UL only when an ID attr is there and pass them via ajax data in this way: { attached : '32,34,38,64,75' } if there is a better way of doing this let me know I want to pass the list items which contain attachments to process. How to get the list item LI which has class of featured e.g. { featured_img : .. } and pass the attachment ID number if featured LI exists, and if none of list items is featured pass featured_img with 0. So i know how to process it via php in the request. Any help is appreciated. Thank you.

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  • How to access a superclass's class attributes in Python?

    - by Brecht Machiels
    Have a look at the following code: class A(object): defaults = {'a': 1} def __getattr__(self, name): print('A.__getattr__') return self.get_default(name) @classmethod def get_default(cls, name): # some debug output print('A.get_default({}) - {}'.format(name, cls)) try: print(super(cls, cls).defaults) # as expected except AttributeError: #except for the base object class, of course pass # the actual function body try: return cls.defaults[name] except KeyError: return super(cls, cls).get_default(name) # infinite recursion #return cls.__mro__[1].get_default(name) # this works, though class B(A): defaults = {'b': 2} class C(B): defaults = {'c': 3} c = C() print('c.a =', c.a) I have a hierarchy of classes each with its own dictionary containing some default values. If an instance of a class doesn't have a particular attribute, a default value for it should be returned instead. If no default value for the attribute is contained in the current class's defaults dictionary, the superclass's defaults dictionary should be searched. I'm trying to implement this using the recursive class method get_default. The program gets stuck in an infinite recursion, unfortunately. My understanding of super() is obviously lacking. By accessing __mro__, I can get it to work properly though, but I'm not sure this is a proper solution. I have the feeling the answer is somewhere in this article, but I haven't been able to find it yet. Perhaps I need to resort to using a metaclass?

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  • Monitoring Html Element CSS Changes in JavaScript

    - by Rick Strahl
    [ updated Feb 15, 2011: Added event unbinding to avoid unintended recursion ] Here's a scenario I've run into on a few occasions: I need to be able to monitor certain CSS properties on an HTML element and know when that CSS element changes. For example, I have a some HTML element behavior plugins like a drop shadow that attaches to any HTML element, but I then need to be able to automatically keep the shadow in sync with the window if the  element dragged around the window or moved via code. Unfortunately there's no move event for HTML elements so you can't tell when it's location changes. So I've been looking around for some way to keep track of the element and a specific CSS property, but no luck. I suspect there's nothing native to do this so the only way I could think of is to use a timer and poll rather frequently for the property. I ended up with a generic jQuery plugin that looks like this: (function($){ $.fn.watch = function (props, func, interval, id) { /// <summary> /// Allows you to monitor changes in a specific /// CSS property of an element by polling the value. /// when the value changes a function is called. /// The function called is called in the context /// of the selected element (ie. this) /// </summary> /// <param name="prop" type="String">CSS Properties to watch sep. by commas</param> /// <param name="func" type="Function"> /// Function called when the value has changed. /// </param> /// <param name="interval" type="Number"> /// Optional interval for browsers that don't support DOMAttrModified or propertychange events. /// Determines the interval used for setInterval calls. /// </param> /// <param name="id" type="String">A unique ID that identifies this watch instance on this element</param> /// <returns type="jQuery" /> if (!interval) interval = 200; if (!id) id = "_watcher"; return this.each(function () { var _t = this; var el$ = $(this); var fnc = function () { __watcher.call(_t, id) }; var itId = null; var data = { id: id, props: props.split(","), func: func, vals: [props.split(",").length], fnc: fnc, origProps: props, interval: interval }; $.each(data.props, function (i) { data.vals[i] = el$.css(data.props[i]); }); el$.data(id, data); hookChange(el$, id, data.fnc); }); function hookChange(el$, id, fnc) { el$.each(function () { var el = $(this); if (typeof (el.get(0).onpropertychange) == "object") el.bind("propertychange." + id, fnc); else if ($.browser.mozilla) el.bind("DOMAttrModified." + id, fnc); else itId = setInterval(fnc, interval); }); } function __watcher(id) { var el$ = $(this); var w = el$.data(id); if (!w) return; var _t = this; if (!w.func) return; // must unbind or else unwanted recursion may occur el$.unwatch(id); var changed = false; var i = 0; for (i; i < w.props.length; i++) { var newVal = el$.css(w.props[i]); if (w.vals[i] != newVal) { w.vals[i] = newVal; changed = true; break; } } if (changed) w.func.call(_t, w, i); // rebind event hookChange(el$, id, w.fnc); } } $.fn.unwatch = function (id) { this.each(function () { var el = $(this); var fnc = el.data(id).fnc; try { if (typeof (this.onpropertychange) == "object") el.unbind("propertychange." + id, fnc); else if ($.browser.mozilla) el.unbind("DOMAttrModified." + id, fnc); else clearInterval(id); } // ignore if element was already unbound catch (e) { } }); return this; } })(jQuery); With this I can now monitor movement by monitoring say the top CSS property of the element. The following code creates a box and uses the draggable (jquery.ui) plugin and a couple of custom plugins that center and create a shadow. Here's how I can set this up with the watcher: $("#box") .draggable() .centerInClient() .shadow() .watch("top", function() { $(this).shadow(); },70,"_shadow"); ... $("#box") .unwatch("_shadow") .shadow("remove"); This code basically sets up the window to be draggable and initially centered and then a shadow is added. The .watch() call then assigns a CSS property to monitor (top in this case) and a function to call in response. The component now sets up a setInterval call and keeps on pinging this property every time. When the top value changes the supplied function is called. While this works and I can now drag my window around with the shadow following suit it's not perfect by a long shot. The shadow move is delayed and so drags behind the window, but using a higher timer value is not appropriate either as the UI starts getting jumpy if the timer's set with too small of an increment. This sort of monitor can be useful for other things as well where operations are maybe not quite as time critical as a UI operation taking place. Can anybody see a better a better way of capturing movement of an element on the page?© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  JavaScript  jQuery  

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