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  • Remove duplicate records/objects uniquely identified by multiple attributes

    - by keruilin
    I have a model called HeroStatus with the following attributes: id user_id recordable_type hero_type (can be NULL!) recordable_id created_at There are over 100 hero_statuses, and a user can have many hero_statuses, but can't have the same hero_status more than once. A user's hero_status is uniquely identified by the combination of recordable_type + hero_type + recordable_id. What I'm trying to say essentially is that there can't be a duplicate hero_status for a specific user. Unfortunately, I didn't have a validation in place to assure this, so I got some duplicate hero_statuses for users after I made some code changes. For example: user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2010-05-03 18:30:30' user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2009-03-03 15:30:00' user_id = 18 recordable_type = 'Good' hero_type = 'Hugs' recordable_id = 1 created_at = '2009-02-03 12:30:00' user_id = 18 recordable_type = 'Good' hero_type = NULL recordable_id = 2 created_at = '2009-012-03 08:30:00' (Last two are not a dups obviously. First two are.) So what I want to do is get rid of the duplicate hero_status. Which one? The one with the most-recent date. I have three questions: How do I remove the duplicates using a SQL-only approach? How do I remove the duplicates using a pure Ruby solution? Something similar to this: http://stackoverflow.com/questions/2790004/removing-duplicate-objects. How do I put a validation in place to prevent duplicate entries in the future?

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  • In my cakephp project the save function is not working?

    - by Faheem
    My controller action is: function add() { if (!empty($this-data)) { $this-Customer-create(); if ($this-Customer-save($this-data)) { $this-Session-setFlash('A new Customer has been added'); $this-redirect(array('action'='index')); } else { $this-Session-setFlash('The customer cannot be added this time. Try again later.'); $this-redirect(array('action'='index')); } } } My model is: class Customer extends AppModel { var $name = 'Customer'; var $validate = array( 'name' = array( 'length'= array( 'rule' = array('between', 4,50), 'message' = 'Name must be minimum 4 and maximum 50 characters long.' ), 'checkUnique'= array( 'rule' = 'isUnique', 'message' = 'This Name is already registered' ) )); and this is my view: create('Customer',array('action'='add'));? input('Customer.name'); echo $form-input('Customer.balance',array('type'='hidden','default'=0)); ? end('Submit');? every time I submit the form it splashes: The customer cannot be added this time. Try again later.

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  • Hierarchical/Nested Database Structure for Comments

    - by Stephen Melrose
    Hi, I'm trying to figure out the best approach for a database schema for comments. The problem I'm having is that the comments system will need to allow nested/hierarchical comments, and I'm not sure how to design this out properly. My requirements are, Comments can be made on comments, so I need to store the tree hierarchy I need to be able to query the comments in the tree hierarchy order, but efficiently, preferably in a fast single query, but I don't know if this is possible I'd need to make some wierd queries, e.g. pull out the latest 5 root comments, and a maximum of 3 children for each one of those I read an article on the MySQL website on this very subject, http://dev.mysql.com/tech-resources/articles/hierarchical-data.html The "Nested Set Model" in theory sounds like it will do what I need, except I'm worried about querying the thing, and also inserting. If this is the right approach, How would I do my 3rd requirement above? If I have 2000 comments, and I add a new sub-comment on the first comment, that will be a LOT of updating to do. This doesn't seem right to me? Or is there a better approach for the type of data I'm wanting to store and query? Thank you

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  • How to load entities into readonly collections using the entity framework

    - by Anton P
    I have a POCO domain model which is wired up to the entity framework using the new ObjectContext class. public class Product { private ICollection<Photo> _photos; public Product() { _photos = new Collection<Photo>(); } public int Id { get; set; } public string Name { get; set; } public virtual IEnumerable<Photo> Photos { get { return _photos; } } public void AddPhoto(Photo photo) { //Some biz logic //... _photos.Add(photo); } } In the above example i have set the Photos collection type to IEnumerable as this will make it read only. The only way to add/remove photos is through the public methods. The problem with this is that the Entity Framework cannot load the Photo entities into the IEnumerable collection as it's not of type ICollection. By changing the type to ICollection will allow callers to call the Add mentod on the collection itself which is not good. What are my options?

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  • Trying to replace contents of a Div, with no luck

    - by bluedaniel
    Ive tried to use the Dom model with no bloody luck, getElementByID just doesnt work for me. I loathe to resort to a regex but not sure what else to do. The idea is to replace a <div id="content_div"> all sorts </div> with a new <div id="content_div"> NEW ALL SORTS HERE </div> and keep anything that was before or after it in the string. The string is a partial HTML string and more specifically out of the wordpress Posts DB. Any ideas? UPDATE: I tagged this question PHP but probably should of mentioned Im looking for a PHP solution only. Update: Code Example $content = ($wpdb->get_var( "SELECT `post_content` FROM $wpdb->posts WHERE ID = {$article[post_id]}" )); $doc = new DOMDocument(); $doc->validateOnParse = true; $doc->loadHTMLFile($content); $element = $doc->getElementById('div_to_edit'); So Ive tried a whole lot of code and this is what Ive got so far, probably not right but Ive been hacking at it for a little while now.

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  • Getting values from the html to the controller

    - by tina
    Hi, I'm trying to access the values a user introduces in a table from my controller. This table is NOT part of the model, and the view source code is something like: <table id="tableSeriales" summary="Seriales" class="servicesT" cellspacing="0" style="width: 100%"> <tr> <td class="servHd">Seriales</td> </tr> <tr id="t0"> <td class="servBodL"> <input id="0" type="text" value="1234" onkeypress = "return handleKeyPress(event, this.id);"/> <input id="1" type="text" value="578" onkeypress = "return handleKeyPress(event, this.id);"/> . . . </td> </tr> </table> How can I get those values (1234, 578) from the controller? Receiving a formcollection doesn't work since it does not get the table... Thank you.

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  • Why would ASP.NET MVC use session state?

    - by ray247
    Recommended by the ASP.NET team to use cache instead of session, we stopped using session from working with the WebForm model the last few years. So we normally have the session turned off in the web.config <sessionState mode="Off" /> But, now when I'm testing out a ASP.NET MVC application with this setting it throw an error in class SessionStateTempDataProvider inside the mvc framework, it asked me to turn on session state, I did and it worked. Looking at the source it uses session Dictionary<string, object> tempDataDictionary = httpContext.Session[TempDataSessionStateKey] as Dictionary<string, object>; // line 20 in SessionStateTempDataProvider.cs So, why would they use session here? What am I missing? Thanks, Ray. ======================================================== Edit Sorry didn't mean for this post to debate on session vs. cache, but rather in the context of the ASP.NET MVC, I was just wondering why session is used here. In this Scott Watermasysk blog post he mentioned on turning off session too as a good practice, so I'm just wondering do I have to turn it on to use MVC from here on?

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  • Is WordPress MVC compliant?

    - by kovshenin
    Some people consider WordPress a blogging platform, some think of it as a CMS, some refer to WordPress as a development framework. Whichever it is, the question still remains. Is WordPress MVC compliant? I've read the forums and somebody asked about MVC about three years ago. There were some positive answers, and some negative ones. While nobody knows exactly what MVC is and everybody thinks of it in their own way, there's still a general concept that's present in all the discussions. I have little experience with MVC frameworks and there doesn't seem to be anything about the framework itself. Most of the MVC is done by the programmer, am I right? Now, going back to WordPress, could we consider the core rewrite engine (WP_Rewrite) the controller? Queries & plugin logic as the model? And themes as the view? Or am I getting it all wrong? Thanks ;)

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  • LinqToSQL not updating database

    - by codegarten
    Hi. I created a database and dbml in visual studio 2010 using its wizards. Everything was working fine until i checked the tables data (also in visual studio server explorer) and none of my updates were there. using (var context = new CenasDataContext()) { context.Log = Console.Out; context.Cenas.InsertOnSubmit(new Cena() { id = 1}); context.SubmitChanges(); } This is the code i am using to update my database. At this point my database has one table with one field (PK) named ID. *INSERT INTO [dbo].Cenas VALUES (@p0) -- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [1] -- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1* This is LOG from the execution (printed the context log into the console). The problem i'm having is that these updates are not persistent in the database. I mean that when i query my database (visual studio server explorer - new query) i see the table is empty, every time. I am using a SQL Server database file (.mdf).

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  • Checking for nil in view in Ruby on Rails

    - by seaneshbaugh
    I've been working with Rails for a while now and one thing I find myself constantly doing is checking to see if some attribute or object is nil in my view code before I display it. I'm starting to wonder if this is always the best idea. My rationale so far has been that since my application(s) rely on user input unexpected things can occur. If I've learned one thing from programming in general it's that users inputting things the programmer didn't think of is one of the biggest sources of run-time errors. By checking for nil values I'm hoping to sidestep that and have my views gracefully handle the problem. The thing is though I typically for various reasons have similar nil or invalid value checks in either my model or controller code. I wouldn't call it code duplication in the strictest sense, but it just doesn't seem very DRY. If I've already checked for nil objects in my controller is it okay if my view just assumes the object truly isn't nil? For attributes that can be nil that are displayed it makes sense to me to check every time, but for the objects themselves I'm not sure what is the best practice. Here's a simplified, but typical example of what I'm talking about: controller code def show @item = Item.find_by_id(params[:id]) @folders = Folder.find(:all, :order => 'display_order') if @item == nil or @item.folder == nil redirect_to(root_url) and return end end view code <% if @item != nil %> display the item's attributes here <% if @item.folder != nil %> <%= link_to @item.folder.name, folder_path(@item.folder) %> <% end %> <% else %> Oops! Looks like something went horribly wrong! <% end %> Is this a good idea or is it just silly?

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  • Alternatives to the Entity Framework for Serving/Consuming an OData Interface

    - by Egahn
    I'm researching how to set up an OData interface to our database. I would like to be able to pull/query data from our DB into Excel, as a start. Eventually I would like to have Excel run queries and pull data over HTTP from a remote client, including authentication, etc. I've set up a working (rickety) prototype so far, using the ADO.NET Entity Data Model wizard in Visual Studio, and VSTO to create a test Excel worksheet with a button to pull from that ADO.NET interface. This works OK so far, and I can query the DB using Linq through the entities/objects that are created by the ADO.NET EDM wizard. However, I have started to run into some problems with this approach. I've been finding the Entity Framework difficult to work with (and in fact, also difficult to research solutions to, as there's a lot of chaff out there regarding it and older versions of it). An example of this is my being unable to figure out how to set the SQL command timeout (as opposed to the HTTP request timeout) on the DataServiceContext object that the wizard generates for my schema, but that's not the point of my question. The real question I have is, if I want to use OData as my interface standard, am I stuck with the Entity Framework? Are there any other solutions out there (preferably open source) which can set up, serve and consume an OData interface, and are easier to work with and less bloated than the Entity Framework? I have seen mention of NHibernate as an alternative, but most of the comparison threads I've seen are a few years old. Are there any other alternatives out there now? Thanks very much!

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  • Silverlight 4 ComboBox - Binding to Nullable data (tried TargetNullValue but not working as expected)

    - by Laurence
    (Please note - I am a Silverlight beginner and am looking for the simplest solution here, e.g. that doesn't involve writing/installing a replacement for the ComboBox control!) This is an issue with a Silverlight 4 application that uses the View Model (MVVM) approach. I have a simple form for editing a "Product" object. Product has a CategoryID property which is nullable (int?). A ComboBox is used to view and set the CategoryID - this is bound to an ObservableCollection of Categories. Product also has number of non-nullable properties bound to TextBoxes. I want the user to see "N/A" in the ComboBox for a product with no category, and to be use this "N/A" option to set CategoryID to null. So, I manually added a Category object with CategoryID=0 and CategoryName="N/A" to the collection; then I set TargetNullValue=0 in the SelectedValue Binding of the ComboBox. My thinking was - when the ComboBox SelectedValue was bound to a null CategoryID it would substitute zero, and therefore select the "N/A" option. When editing a Product with a non-null CategoryID, everything works. However when a null CategoryID is found, two problems occur: No option is selected in the ComboBox (its blank) The ComboBox binding seems broken from this point onwards - any Product I subsequently edit (incl. ones with a non-null CategoryID) have nothing selected in the ComboBox (its still populated with all categories - just no selected item). I've seen reports of problem #2 (here, here) but I was under the impression that #1 should have worked. What am I missing to get the "N/A" option to be selected? XAML for ComboBox: <ComboBox x:Name="cboCategory" ItemsSource="{Binding colCategories, Mode=OneWay}" SelectedValuePath="CategoryID" DisplayMemberPath="CategoryName" SelectedValue="{Binding CurrentProduct.CategoryID, Mode=TwoWay, TargetNullValue=0}" Height="24" Width="344"></ComboBox>

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  • How do you convert a parent-child (adjacency) table to a nested set using PHP and MySQL?

    - by mrbinky3000
    I've spent the last few hours trying to find the solution to this question online. I've found plenty of examples on how to convert from nested set to adjacency... but few that go the other way around. The examples I have found either don't work or use MySQL procedures. Unfortunately, I can't use procedures for this project. I need a pure PHP solution. I have a table that uses the adjacency model below: id parent_id category 1 0 ROOT_NODE 2 1 Books 3 1 CD's 4 1 Magazines 5 2 Books/Hardcover 6 2 Books/Large Format 7 4 Magazines/Vintage And I would like to convert it to a Nested Set table below: id left right category 1 1 14 Root Node 2 2 7 Books 3 3 4 Books/Hardcover 4 5 6 Books/Large Format 5 8 9 CD's 6 10 13 Magazines 7 11 12 Magazines/Vintage Here is an image of what I need: I have a function, based on the pseudo code from this forum post (http://www.sitepoint.com/forums/showthread.php?t=320444) but it doesn't work. I get multiple rows that have the same value for left. This should not happen. <?php /** -- -- Table structure for table `adjacent_table` -- CREATE TABLE IF NOT EXISTS `adjacent_table` ( `id` int(11) NOT NULL AUTO_INCREMENT, `father_id` int(11) DEFAULT NULL, `category` varchar(128) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ; -- -- Dumping data for table `adjacent_table` -- INSERT INTO `adjacent_table` (`id`, `father_id`, `category`) VALUES (1, 0, 'ROOT'), (2, 1, 'Books'), (3, 1, 'CD''s'), (4, 1, 'Magazines'), (5, 2, 'Hard Cover'), (6, 2, 'Large Format'), (7, 4, 'Vintage'); -- -- Table structure for table `nested_table` -- CREATE TABLE IF NOT EXISTS `nested_table` ( `id` int(11) NOT NULL AUTO_INCREMENT, `lft` int(11) DEFAULT NULL, `rgt` int(11) DEFAULT NULL, `category` varchar(128) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; */ mysql_connect('localhost','USER','PASSWORD') or die(mysql_error()); mysql_select_db('DATABASE') or die(mysql_error()); adjacent_to_nested(0); /** * adjacent_to_nested * * Reads a "adjacent model" table and converts it to a "Nested Set" table. * @param integer $i_id Should be the id of the "root node" in the adjacent table; * @param integer $i_left Should only be used on recursive calls. Holds the current value for lft */ function adjacent_to_nested($i_id, $i_left = 0) { // the right value of this node is the left value + 1 $i_right = $i_left + 1; // get all children of this node $a_children = get_source_children($i_id); foreach ($a_children as $a) { // recursive execution of this function for each child of this node // $i_right is the current right value, which is incremented by the // import_from_dc_link_category method $i_right = adjacent_to_nested($a['id'], $i_right); // insert stuff into the our new "Nested Sets" table $s_query = " INSERT INTO `nested_table` (`id`, `lft`, `rgt`, `category`) VALUES( NULL, '".$i_left."', '".$i_right."', '".mysql_real_escape_string($a['category'])."' ) "; if (!mysql_query($s_query)) { echo "<pre>$s_query</pre>\n"; throw new Exception(mysql_error()); } echo "<p>$s_query</p>\n"; // get the newly created row id $i_new_nested_id = mysql_insert_id(); } return $i_right + 1; } /** * get_source_children * * Examines the "adjacent" table and finds all the immediate children of a node * @param integer $i_id The unique id for a node in the adjacent_table table * @return array Returns an array of results or an empty array if no results. */ function get_source_children($i_id) { $a_return = array(); $s_query = "SELECT * FROM `adjacent_table` WHERE `father_id` = '".$i_id."'"; if (!$i_result = mysql_query($s_query)) { echo "<pre>$s_query</pre>\n"; throw new Exception(mysql_error()); } if (mysql_num_rows($i_result) > 0) { while($a = mysql_fetch_assoc($i_result)) { $a_return[] = $a; } } return $a_return; } ?> This is the output of the above script. INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '2', '5', 'Hard Cover' ) INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '2', '7', 'Large Format' ) INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '1', '8', 'Books' ) INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '1', '10', 'CD\'s' ) INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '10', '13', 'Vintage' ) INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '1', '14', 'Magazines' ) INSERT INTO nested_table (id, lft, rgt, category) VALUES( NULL, '0', '15', 'ROOT' ) As you can see, there are multiple rows sharing the lft value of "1" same goes for "2" In a nested-set, the values for left and right must be unique. Here is an example of how to manually number the left and right ID's in a nested set: UPDATE - PROBLEM SOLVED First off, I had mistakenly believed that the source table (the one in adjacent-lists format) needed to be altered to include a source node. This is not the case. Secondly, I found a cached page on BING (of all places) with a class that does the trick. I've altered it for PHP5 and converted the original author's mysql related bits to basic PHP. He was using some DB class. You can convert them to your own database abstraction class later if you want. Obviously, if your "source table" has other columns that you want to move to the nested set table, you will have to adjust the write method in the class below. Hopefully this will save someone else from the same problems in the future. <?php /** -- -- Table structure for table `adjacent_table` -- DROP TABLE IF EXISTS `adjacent_table`; CREATE TABLE IF NOT EXISTS `adjacent_table` ( `id` int(11) NOT NULL AUTO_INCREMENT, `father_id` int(11) DEFAULT NULL, `category` varchar(128) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ; -- -- Dumping data for table `adjacent_table` -- INSERT INTO `adjacent_table` (`id`, `father_id`, `category`) VALUES (1, 0, 'Books'), (2, 0, 'CD''s'), (3, 0, 'Magazines'), (4, 1, 'Hard Cover'), (5, 1, 'Large Format'), (6, 3, 'Vintage'); -- -- Table structure for table `nested_table` -- DROP TABLE IF EXISTS `nested_table`; CREATE TABLE IF NOT EXISTS `nested_table` ( `lft` int(11) NOT NULL DEFAULT '0', `rgt` int(11) DEFAULT NULL, `id` int(11) DEFAULT NULL, `category` varchar(128) DEFAULT NULL, PRIMARY KEY (`lft`), UNIQUE KEY `id` (`id`), UNIQUE KEY `rgt` (`rgt`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; */ /** * @class tree_transformer * @author Paul Houle, Matthew Toledo * @created 2008-11-04 * @url http://gen5.info/q/2008/11/04/nested-sets-php-verb-objects-and-noun-objects/ */ class tree_transformer { private $i_count; private $a_link; public function __construct($a_link) { if(!is_array($a_link)) throw new Exception("First parameter should be an array. Instead, it was type '".gettype($a_link)."'"); $this->i_count = 1; $this->a_link= $a_link; } public function traverse($i_id) { $i_lft = $this->i_count; $this->i_count++; $a_kid = $this->get_children($i_id); if ($a_kid) { foreach($a_kid as $a_child) { $this->traverse($a_child); } } $i_rgt=$this->i_count; $this->i_count++; $this->write($i_lft,$i_rgt,$i_id); } private function get_children($i_id) { return $this->a_link[$i_id]; } private function write($i_lft,$i_rgt,$i_id) { // fetch the source column $s_query = "SELECT * FROM `adjacent_table` WHERE `id` = '".$i_id."'"; if (!$i_result = mysql_query($s_query)) { echo "<pre>$s_query</pre>\n"; throw new Exception(mysql_error()); } $a_source = array(); if (mysql_num_rows($i_result)) { $a_source = mysql_fetch_assoc($i_result); } // root node? label it unless already labeled in source table if (1 == $i_lft && empty($a_source['category'])) { $a_source['category'] = 'ROOT'; } // insert into the new nested tree table // use mysql_real_escape_string because one value "CD's" has a single ' $s_query = " INSERT INTO `nested_table` (`id`,`lft`,`rgt`,`category`) VALUES ( '".$i_id."', '".$i_lft."', '".$i_rgt."', '".mysql_real_escape_string($a_source['category'])."' ) "; if (!$i_result = mysql_query($s_query)) { echo "<pre>$s_query</pre>\n"; throw new Exception(mysql_error()); } else { // success: provide feedback echo "<p>$s_query</p>\n"; } } } mysql_connect('localhost','USER','PASSWORD') or die(mysql_error()); mysql_select_db('DATABASE') or die(mysql_error()); // build a complete copy of the adjacency table in ram $s_query = "SELECT `id`,`father_id` FROM `adjacent_table`"; $i_result = mysql_query($s_query); $a_rows = array(); while ($a_rows[] = mysql_fetch_assoc($i_result)); $a_link = array(); foreach($a_rows as $a_row) { $i_father_id = $a_row['father_id']; $i_child_id = $a_row['id']; if (!array_key_exists($i_father_id,$a_link)) { $a_link[$i_father_id]=array(); } $a_link[$i_father_id][]=$i_child_id; } $o_tree_transformer = new tree_transformer($a_link); $o_tree_transformer->traverse(0); ?>

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  • WPF ComboBox Binding

    - by MadSeb
    Hi So I have the following model: public class Person { public String FirstName { get; set; } public String LastName { get; set; } public String Address { get; set; } public String EMail { get; set; } public String Phone { get; set; } } public class Order { public Person Pers { get; set;} public Product Prod { get; set; } public List<Person> AllPersons { get; set; } public Order(Person person, Product prod ) { this.Pers = person; this.Prod = prod; AllPersons = database.Persons.GetAll(); } } And I have a WPF window used to edit an order. I set the DataContext to Order. public SetDisplay(Order ord) { DataContext = ord; } I have the following XAML: <ComboBox Name="myComboBox" SelectedItem = "{Binding Path=Pers, Mode=TwoWay}" ItemsSource = "{Binding Path=AllPersons, Mode=OneWay}" DisplayMemberPath = "FirstName" IsEditable="False" /> <Label Name="lblPersonName" Content = "{Binding Path=Pers.FirstName}" /> <Label Name="lblPersonLastName" Content = "{Binding Path=Pers.LastName}" /> <Label Name="lblPersonEMail" Content = "{Binding Path=Pers.EMail}" /> <Label Name="lblPersonAddress" Content = "{Binding Path=Pers.Address}" /> However, the binding does not seem to work.......When I change the selected item , the labels do not update .... Regards!! Any reply is appreciated !!

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  • Store the cache data locally

    - by Lu Lu
    Hello, I develops a C# Winform application, it is a client and connect to web service to get data. The data returned by webservice is a DataTable. Client will display it on a DataGridView. My problem is that: Client will take more time to get all data from server (web service is not local with client). So I must to use a thread to get data. This is my model: Client create a thread to get data - thread complete and send event to client - client display data on datagridview on a form. However, when user closes the form, user can open this form in another time, and client must get data again. This solution will cause the client slowly. So, I think about a cached data: Client <---get/add/edit/delete--- Cached Data ---get/add/edit/delete---Server (web service) Please give me some suggestions. Example: cached data should be developed in another application which is same host with client? Or cached data is running in client. Please give me some techniques to implement this solution. If having any examples, please give me. Thanks.

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  • Setting up relations/mappings for a SQLAlchemy many-to-many database

    - by Brent Ramerth
    I'm new to SQLAlchemy and relational databases, and I'm trying to set up a model for an annotated lexicon. I want to support an arbitrary number of key-value annotations for the words which can be added or removed at runtime. Since there will be a lot of repetition in the names of the keys, I don't want to use this solution directly, although the code is similar. My design has word objects and property objects. The words and properties are stored in separate tables with a property_values table that links the two. Here's the code: from sqlalchemy import Column, Integer, String, Table, create_engine from sqlalchemy import MetaData, ForeignKey from sqlalchemy.orm import relation, mapper, sessionmaker from sqlalchemy.ext.declarative import declarative_base engine = create_engine('sqlite:///test.db', echo=True) meta = MetaData(bind=engine) property_values = Table('property_values', meta, Column('word_id', Integer, ForeignKey('words.id')), Column('property_id', Integer, ForeignKey('properties.id')), Column('value', String(20)) ) words = Table('words', meta, Column('id', Integer, primary_key=True), Column('name', String(20)), Column('freq', Integer) ) properties = Table('properties', meta, Column('id', Integer, primary_key=True), Column('name', String(20), nullable=False, unique=True) ) meta.create_all() class Word(object): def __init__(self, name, freq=1): self.name = name self.freq = freq class Property(object): def __init__(self, name): self.name = name mapper(Property, properties) Now I'd like to be able to do the following: Session = sessionmaker(bind=engine) s = Session() word = Word('foo', 42) word['bar'] = 'yes' # or word.bar = 'yes' ? s.add(word) s.commit() Ideally this should add 1|foo|42 to the words table, add 1|bar to the properties table, and add 1|1|yes to the property_values table. However, I don't have the right mappings and relations in place to make this happen. I get the sense from reading the documentation at http://www.sqlalchemy.org/docs/05/mappers.html#association-pattern that I want to use an association proxy or something of that sort here, but the syntax is unclear to me. I experimented with this: mapper(Word, words, properties={ 'properties': relation(Property, secondary=property_values) }) but this mapper only fills in the foreign key values, and I need to fill in the other value as well. Any assistance would be greatly appreciated.

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  • Tree data in MySql database table

    - by Robert Koritnik
    I have a table that uses Adjacency list model for hierarchy storage. My most relevant columns in this table are therefore: ItemId // is auto_increment ParentId Level ParentTrail // in the form of "parentId/../parentId/itemId" then I created a before insert tigger, that populates columns Level and ParentTrail. Since the last column also includes current item's ID I had to use a trick in my trigger because auto_increment columns are not available in the before insert trigger. So I get that value from the information_schema.tables table. All works fine, until I try to write an update trigger, that would update my item and its descendants when the item changes its parent (ParentId has changed). But I can't make an update on my table inside the update trigger. All I can do is to change current record's values but not other's. I could use a separate table for hierarchy data, but that would mean that I would also have to create a view that would combine these two tables (1:1 relation) and I would like to avoid this is at all possible. Is there a way to have all these in the same table so that these fields (Level and ParetTrail) set/update themselves automagically using triggers?

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  • Where do I put javaassist code?

    - by DutrowLLC
    I have an application running on google app engine. I'm using restlets and I have a couple of layers set up including the restlet layer, the model layer, the business layer, and the data layer. I'm attempting to use javaassist to modify some classes, but I'm unsure where to actually put the code. I tried to put the code in the static initialization block: public class Person { String firstName; String getFirstName(){return null;} static{ ClassPool pool = ClassPool.getDefault(); try { CtClass CtPerson = pool.get("Person"); CtMethod CtGetFirstName = CtPerson.getDeclaredMethod("GetFirstName"); CtGetFirstName.setBody("return firstName;"); CtPerson.toClass(); } catch (Exception e) { e.printStackTrace(); } } } ...but that resulted in this error: javassist.CannotCompileException:.....attempted duplicate class definition...". I guess it makes sense that I can't edit the class file in the middle of its generation. I know the code works because I was able to run it correctly by simply putting it in a location that would run when I sent the program a command. (accessed a Restlet resource). The code ran fine if an instance of the class had not already been instantiated, however once I instantiated an instance of the affected class, the javaassist code failed. I assume I need to put this code somewhere that it will only run either: once after the program starts, directly before a class is instantiated for the first time, or even better, during compile time.

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  • FluentNHibernate mapping of composite foreign keys

    - by Faron
    I have an existing database schema and wish to replace the custom data access code with Fluent.NHibernate. The database schema cannot be changed since it already exists in a shipping product. And it is preferable if the domain objects did not change or only changed minimally. I am having trouble mapping one unusual schema construct illustrated with the following table structure: CREATE TABLE [Container] ( [ContainerId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_Container] PRIMARY KEY ( [ContainerId] ASC ) ) CREATE TABLE [Item] ( [ItemId] [uniqueidentifier] NOT NULL, [ContainerId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_Item] PRIMARY KEY ( [ContainerId] ASC, [ItemId] ASC ) ) CREATE TABLE [Property] ( [ContainerId] [uniqueidentifier] NOT NULL, [PropertyId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_Property] PRIMARY KEY ( [ContainerId] ASC, [PropertyId] ASC ) ) CREATE TABLE [Item_Property] ( [ContainerId] [uniqueidentifier] NOT NULL, [ItemId] [uniqueidentifier] NOT NULL, [PropertyId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_Item_Property] PRIMARY KEY ( [ContainerId] ASC, [ItemId] ASC, [PropertyId] ASC ) ) CREATE TABLE [Container_Property] ( [ContainerId] [uniqueidentifier] NOT NULL, [PropertyId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_Container_Property] PRIMARY KEY ( [ContainerId] ASC, [PropertyId] ASC ) ) The existing domain model has the following class structure: The Property class contains other members representing the property's name and value. The ContainerProperty and ItemProperty classes have no additional members. They exist only to identify the owner of the Property. The Container and Item classes have methods that return collections of ContainerProperty and ItemProperty respectively. Additionally, the Container class has a method that returns a collection of all of the Property objects in the object graph. My best guess is that this was either a convenience method or a legacy method that was never removed. The business logic mainly works with Item (as the aggregate root) and only works with a Container when adding or removing Items. I have tried several techniques for mapping this but none work so I won't include them here unless someone asks for them. How would you map this?

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  • Uploading file is not working

    - by VinTem
    I have done the following form <% form_for @anexo, :url => {:action => "create"}, :html => {:multpart => true} do |f| %> <%= f.error_messages %> <p> <%= f.label :descricao, "Descrição"%> <%= f.text_field :descricao %> </p> <p> <%= f.label :arquivo_anexo, "Arquivo Anexo" %> <%= f.file_field :arquivo_anexo %> </p> <p> <%= f.submit "Adicionar anexo" %> </p> <% end %> With a model like this: def arquivo_anexo=(novo_arqquivo) self.arquivo = novo_arquivo.read self.nome = File.basename(novo_arquivo.original_filename) self.content_type = novo_arquivo.content_type.chomp end But when I my file is not been sent through the form. When I check the params array using the debugger the data is not sent. Does anyone have any idea or sugestions? Thanks

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  • Postgres error with Sinatra/Haml/DataMapper on Heroku

    - by sevennineteen
    I'm trying to move a simple Sinatra app over to Heroku. Migration of the Ruby app code and existing MySQL database using Taps went smoothly, but I'm getting the following Postgres error: PostgresError - ERROR: operator does not exist: text = integer LINE 1: ...d_at", "post_id" FROM "comments" WHERE ("post_id" IN (4, 17,... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. It's evident that the problem is related to a type mismatch in the query, but this is being issued from a Haml template by the DataMapper ORM at a very high level of abstraction, so I'm not sure how I'd go about controlling this... Specifically, this seems to be throwing up on a call of p.comments from my Haml template, where p represents a given post. The Datamapper models are related as follows: class Post property :id, Serial ... has n, :comments end class Comment property :id, Serial ... belongs_to :post end This works fine on my local and current hosted environment using MySQL, but Postgres is clearly more strict. There must be hundreds of Datamapper & Haml apps running on Postgres DBs, and this model relationship is super-conventional, so hopefully someone has seen (and determined how to fix) this. Thanks!

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  • 3D Animation Rotating and Translating simultaneously in WPF

    - by sklitzz
    Hi, I have ModelVisual3D of a cube. I want to translate and rotate it at the same time. I wish the center of rotation to be in the middle of the cube(the cube rotates around its own axis). But when I try to do this applying both transformations the effect is not what you would expect. Since the object is translating the center of rotation is different thus making it move and rotate in a strange way. How do I get the desired effect? Transform3DGroup transGroup = new Transform3DGroup(); DoubleAnimation cardAnimation = new DoubleAnimation(); cardAnimation.From = 0; cardAnimation.To = 3; cardAnimation.Duration = new Duration(TimeSpan.FromSeconds(2)); Transform3D transform = new TranslateTransform3D(0,0,0); transGroup.Children.Add(transform); RotateTransform3D rotateTransform = new RotateTransform3D(); AxisAngleRotation3D rotateAxis = new AxisAngleRotation3D(new Vector3D(0, 1, 0), 180); Rotation3DAnimation rotateAnimation = new Rotation3DAnimation(rotateAxis, TimeSpan.FromSeconds(2)); rotateAnimation.DecelerationRatio = 0.8; transGroup.Children.Add(rotateTransform); Model.Transform = transGroup; transform.BeginAnimation(TranslateTransform3D.OffsetXProperty, cardAnimation); rotateTransform.BeginAnimation(RotateTransform3D.RotationProperty, rotateAnimation);

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  • Creating futures using Apple's GCD

    - by jer
    I'm working on a library which implements the actor model on top of Grand Central Dispatch (specifically the C level API libdispatch). Basically a brief overview of my system is as such: Communication happens between actors using messages Multicast communication only (one actor to many actors) Senders and receivers are decoupled from one another using a blackboard where messages are pushed to. Messages are sent in the default queue asynchronously using dispatch_group_async() once a message gets pushed onto the blackboard. I'm trying to implement futures in the language right now, so I've created a new type which holds some information: A group of its own The value being 'returned' However, I have a problem since dispatch_block_t is of type void (^)(void) so it doesn't return anything. So my idea of in my future_new() function of setting up another group which can be used to execute a block returning a result, which I can store in my "value" member in my future_t structure, isn't going to work. The rest of the futures implementation is very clear, except it all depends on being able to get the value into the future back from the actor, acting on the message. When using the library, it would greatly reduce its usefulness if I had to ask users (and myself) to be aware when futures were going to be used by other parts of the system—It just isn't practical. I'm wondering if anyone can think of a way around this?

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  • What changes in Core Data after a save?

    - by Splash6
    I have a Core Data based mac application that is working perfectly well until I save a file. When I save a file it seems like something changes in core data because my original fetch request no longer fetches anything. This is the fetch request that works before saving but returns an empty array after saving. NSEntityDescription *outputCellEntityDescription = [NSEntityDescription entityForName:@"OutputCell" inManagedObjectContext:[[self document] managedObjectContext]]; NSFetchRequest *outputCellRequest = [[[NSFetchRequest alloc] init] autorelease]; [outputCellRequest setEntity:outputCellEntityDescription]; NSPredicate *outputCellPredicate = [NSPredicate predicateWithFormat:@"(cellTitle = %@)", outputCellTitle]; [outputCellRequest setPredicate:outputCellPredicate]; NSError *outputCellError = nil; NSArray *outputCellArray = [[[self document] managedObjectContext] executeFetchRequest:outputCellRequest error:&outputCellError]; I have checked with [[[self document] managedObjectContext] registeredObjects] to see that the object still exists after the save and nothing seems to have changed and the object still exists. It is probably something fairly basic but does anyone know what I might be doing wrong? If not can anyone give me any pointers to what might be different in the Core Data model after a save so I might have some clues why the fetch request stops working after saving?

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  • Linq to SQL code generator features

    - by Anders Abel
    I'm very fond of Linq to SQL and the programming model it encourages. I think that in many cases when you are in control of both the database schema and the code it is not worth the effort to have different relational and object models for the data. Working with Linq to SQL makes it simple to have type safe data access from .NET, using the partial extension methods to implement business rules. Unfortunately I do not like the dbml designer due to the lack of a schema refresh function. So far I have used SqlMetal, but that lacks the customization options of the dbml designer. Because of that I've started working on a tool which regenerates the whole code file like SqlMetal, but has the ability to do the customizations that are available in the dbml designer (and maybe more in the future). The customizations will be described in an xml file which only contains those parts that shouldn't have default values. This should keep the xml file size down as well as the maintenance burden of it. To help me focus on the right features, I would like to know: What would be your favourite feature in a linq to sql code generator?

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