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  • has_many relation doesn't seems right or logical, some thing like belongs_to_many looks right

    - by Vijendra
    My situation is like this. Company has many users and users may belongs to many companies. And current implementation is something like below. class Company has_many :employments has_many :users, :through = :employments end class Employment belongs_to :company belongs_to :user end class User has_many :employments has_many :companies, :through = :employments #This doesn't looks correct end User has many companies doesn't looks logically meaningful.It must be some thing like belongs_to_many companies. Do I need to use has_and_belongs_to_many? But that also will gives the same meaning. Can some one please suggest the right way for representing these relationships?

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  • When is it safe to do a Response.Redirect() without throwing an exception?

    - by DDechant
    I have an intermediary class extending System.Web.UI.Page for all of my pages that require authentication. The class mostly does custom authentication handling. When a user with insufficient access attempts to visit a page, I try to redirect the user back to the login page while preventing any further page events from being executed (ie. Page_load). The first solution that came to mind was the default implementation of Response.Redirect. Of course the downside to this is the possibility of ThreadAbortExceptions being thrown. So my question is this: When (if at all) during the page life cycle is it actually safe to execute Response.Redirect() without ThreadAbortException ever being thrown? public class CustomPage : System.Web.UI.Page { protected override void OnInit(EventArgs e) { base.OnInit(e); if (!IsValid()) Response.Redirect("login.aspx", true); } }

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  • Grails: Duplicates & unique constraint validation

    - by rukoche
    OK here is stripped down version of what I have in my app Artist domain: class Artist { String name Date lastMined def artistService static transients = ['artistService'] static hasMany = [events: Event] static constraints = { name(unique: true) lastMined(nullable: true) } def mine() { artistService.mine(this) } } Event domain: class Event { String name String details String country String town String place String url String date static belongsTo = [Artist] static hasMany = [artists: Artist] static constraints = { name(unique: true) url(unique: true) } } ArtistService: class ArtistService { def results = [ [ name:"name", details:"details", country:"country", town:"town", place:"place", url:"url", date:"date" ] ] def mine(Artist artist) { results << results[0] // now we have a duplicate results.each { def event = new Event(it) if (event.validate()) { if (artist.events.find{ it.name == event.name }) { log.info "grrr! valid duplicate name: ${event.name}" } artist.addToEvents(event) } } artist.lastMined = new Date() if (artist.events) { artist.save(flush: true) } } } In theory event.validate() should return false and event will not be added to artist, but it doesn't.. which results in DB exception on artist.save() Although I noticed that if duplicate event is persisted first everything works as intended. Is it bug or feature? :P

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  • Reuse C++ Header files

    - by Amrish
    Guys, I have a Visual C++ solution with 2 projects AlgorithmA & AlgorithmB and both share a common header file RunAlgo.h with the class declaration. Each project in the solution has its own unique implementation for the header file. I am trying to compile a DLL out of the common header file RunAlgo.h and add reference to this DLL in the projects AlgorithmA & AlgorithmB. I have then included separate RunAlgo.cpp definition file in both my projects. The problem is that I am getting linker errors while compiling the new DLL project which has only the header file. So, the question is Can a header file with only class declaration be compiled into a DLL (Similar to class library containing an Interface in C#)? For the above scenario, is there a better approach to reuse the common Header file among projects? Should the above method work (re-check my code?)

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  • jsp update request happens to be invoked by a link

    - by Akshatha
    <tr class="bg-row1"> <td class="td-highlighted-2"> <div align="left"><a href="<%=contextPath%>/jsp/admin/UpdateProject.jsp"><%=searchList1.getProjid()%></a></div> </td> <td class="td-highlighted-2"> <div align="left"><%=searchList1.getProjname()%></div> </td> </tr> here jsp update request happens to be invoked by a link in updateproject.jsp how can i refer projid and projname value in a text box

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  • mapping 'value object' collection in (Fluent) NHibernate

    - by adrin
    I have the following entity public class Employee { public virtual int Id {get;set;} public virtual ISet<Hour> XboxBreakHours{get;set} public virtual ISet<Hour> CoffeeBreakHours {get;set} } public class Hour { public DateTime Time {get;set;} } (What I want to do here is store information that employee A plays Xbox everyday let's say at 9:00 13:30 and has a coffee break everyday at 7:00 12:30 18:00) - I am not sure if my approach is valid at all here. The question is how should my (ideally fluent) mappings look like here? It is not necessary (from my point of view) for Hour class to have Id or be accessible from some kind of repository.

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  • Segfault when calling a method c++

    - by shuttle87
    I am fairly new to c++ and I am a bit stumped by this problem. I am trying to assign a variable from a call to a method in another class but it always segfaults. My code compiles with no warnings and I have checked that all variables are correct in gdb but the function call itself seems to cause a segfault. The code I am using is roughly like the following: class History{ public: bool test_history(); }; bool History::test_history(){ std::cout<<"test"; //this line never gets executed //more code goes in here return true; } class Game{ private: bool some_function(); public: History game_actions_history; bool local_variable; }; bool Game::some_function(){ local_variable = game_actions_history.test_history(); if (local_variable == true){ return true; } else{ return false; } } Any tips or advice is greatly appreciated!

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  • Casting objects to Integer,string ,...

    - by Milan
    Hello everybody! I have one small problem. I have list of types(int,string,..) ArrayList<Class> typeList; and I have some input values; ArrayList<Object> values; How to cast some value to some type if I know which type from the typeList is the values; typeList.get(i).cast(values.get(i)); <- this is not working??? Actualy I generate dynamic form in runtime. With Java reflection I get parameterTypes from methods from some class, I generate form with input fields and then i want to cast the text from the input fields to specific types from the paramterTypes that I got with Java reflection from some class.

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  • [C++] std::string manipulation: whitespace, "newline escapes '\'" and comments #

    - by rubenvb
    Kind of looking for affirmation here. I have some hand-written code, which I'm not shy to say I'm proud of, which reads a file, removes leading whitespace, processes newline escapes '\' and removes comments starting with #. It also removes all empty lines (also whitespace-only ones). Any thoughts/recommendations? I could probably replace some std::cout's with std::runtime_errors... but that's not a priority here :) const int RecipeReader::readRecipe() { ifstream is_recipe(s_buffer.c_str()); if (!is_recipe) cout << "unable to open file" << endl; while (getline(is_recipe, s_buffer)) { // whitespace+comment removeLeadingWhitespace(s_buffer); processComment(s_buffer); // newline escapes + append all subsequent lines with '\' processNewlineEscapes(s_buffer, is_recipe); // store the real text line if (!s_buffer.empty()) v_s_recipe.push_back(s_buffer); s_buffer.clear(); } is_recipe.close(); return 0; } void RecipeReader::processNewlineEscapes(string &s_string, ifstream &is_stream) { string s_temp; size_t sz_index = s_string.find_first_of("\\"); while (sz_index <= s_string.length()) { if (getline(is_stream,s_temp)) { removeLeadingWhitespace(s_temp); processComment(s_temp); s_string = s_string.substr(0,sz_index-1) + " " + s_temp; } else cout << "Error: newline escape '\' found at EOF" << endl; sz_index = s_string.find_first_of("\\"); } } void RecipeReader::processComment(string &s_string) { size_t sz_index = s_string.find_first_of("#"); s_string = s_string.substr(0,sz_index); } void RecipeReader::removeLeadingWhitespace(string &s_string) { const size_t sz_length = s_string.size(); size_t sz_index = s_string.find_first_not_of(" \t"); if (sz_index <= sz_length) s_string = s_string.substr(sz_index); else if ((sz_index > sz_length) && (sz_length != 0)) // "empty" lines with only whitespace s_string.clear(); } Some extra info: the first s_buffer passed to the ifstream contains the filename, std::string s_buffer is a class data member, so is std::vector v_s_recipe. Any comment is welcome :)

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  • How to get the age from a birthdate using PHP & MySQL?

    - by TaG
    I ask my users for their birthdate and store it in my database in the following way $month $day $year output May 6 1901 but I was wondering how can I get the age from the stored birthdate using PHP & MySQL? Here is the PHP code. if (isset($_POST['submitted'])) { $mysqli = mysqli_connect("localhost", "root", "", "sitename"); $dbc = mysqli_query($mysqli,"SELECT users.* FROM users WHERE user_id=3"); $month_options = array("Month", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"); $day_options = array("Day", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31"); $month = mysqli_real_escape_string($mysqli, htmlentities(strip_tags($_POST['month']))); $day = mysqli_real_escape_string($mysqli, htmlentities(strip_tags($_POST['day']))); $year = mysqli_real_escape_string($mysqli, htmlentities(strip_tags($_POST['year']))); if (mysqli_num_rows($dbc) == 0) { $mysqli = mysqli_connect("localhost", "root", "", "sitename"); $dbc = mysqli_query($mysqli,"INSERT INTO users (user_id, month, day, year) VALUES ('$user_id', '$month', '$day', '$year')"); } if ($dbc == TRUE) { $dbc = mysqli_query($mysqli,"UPDATE users SET month = '$month', day = '$day', year = '$year' WHERE user_id = '$user_id'"); echo '<p class="changes-saved">Your changes have been saved!</p>'; } if (!$dbc) { print mysqli_error($mysqli); return; } } Here is the html. <form method="post" action="index.php"> <fieldset> <ul> <li><label>Date of Birth: </label> <label for="month" class="hide">Month: </label> <?php // month options echo '<select name="month" id="month">' . "\n"; foreach($month_options as $option) { if ($option == $month) { echo '<option value="' . stripslashes(htmlentities(strip_tags($option))) . '" selected="selected">' . stripslashes(htmlentities(strip_tags($option))) . '</option>' . "\n"; } else { echo '<option value="'. stripslashes(htmlentities(strip_tags($option))) . '">' . stripslashes(htmlentities(strip_tags($option))) . '</option>'."\n"; } } echo '</select>'; ?> <label for="day" class="hide">Day: </label> <?php // day options echo '<select id="day" name="day">' . "\n"; foreach($day_options as $option) { if ($option == $day) { echo '<option value="' . stripslashes(htmlentities(strip_tags($option))) . '" selected="selected">' . stripslashes(htmlentities(strip_tags($option))) . '</option>' . "\n"; } else { echo '<option value="'. stripslashes(htmlentities(strip_tags($option))) . '">' . stripslashes(htmlentities(strip_tags($option))) . '</option>'."\n"; } } echo '</select>'; ?> <label for="year" class="hide">Year: </label><input type="text" name="year" id="year" size="4" maxlength="4" value="<?php if (isset($_POST['year'])) { echo stripslashes(htmlentities(strip_tags($_POST['year']))); } else if(!empty($year)) { echo stripslashes(htmlentities(strip_tags($year))); } ?>" /></li> <li><input type="submit" name="submit" value="Save Changes" class="save-button" /> <input type="hidden" name="submitted" value="true" /> <input type="submit" name="submit" value="Preview Changes" class="preview-changes-button" /></li> </ul> </fieldset> </form>

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  • Hibernate - why use many-to-one to represent a one-to-one?

    - by aberrant80
    I've seen people use many-to-one mappings to represent one-to-one relationships. I've also read this in a book by Gavin King and on articles. For example, if a customer can have exactly one shipping address, and a shipping address can belong to only one customer, the mapping is given as: <class name="Customer" table="CUSTOMERS"> ... <many-to-one name="shippingAddress" class="Address" column="SHIPPING_ADDRESS_ID" cascade="save-update" unique="true"/> ... </class> The book reasons as (quoting it): "You don't care what's on the target side of the association, so you can treat it like a to-one association without the many part." My question is, why use many-to-one and not one-to-one? What is it about a one-to-one that makes it a less desirable option to many-to-one? Thanks.

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  • Exception and Inheritance in JAVA

    - by user1759950
    Suppose we have this problem public class Father{ public void method1(){...} } public class Child1 extends Father{ public void method1() throws Exception{ super.method1(); ... } } Child1 extends Father and override method1 but given implementation Child1.method1 now throws a exception, this wont compile as override method can't throw new exceptions. What is the best solution? Propagate the required exception to the Father.. to me this is against encapsulation, inheritance and general OOP ( the father potentially throw and exception that will never happen ) Use a RuntimeException instead? This solution wont propagate the Exception to the father but I read In Oracle docs and others sources states class of exceptions should be used when "Client code cannot do anything" this is not that case, this exception will b useful to recover blablabla ( why is wrong to use RuntimeException instead? ) Other.. thanks, Federico

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  • Generics and reflection in Java

    - by Ragesh
    This is probably a very basic question, but I'm really new to generics in Java and I'm having a hard time altering my thought process from the way things are done in C#, so bear with me. I'm trying to build a generic repository in Java. I've created an IRepository interface that looks like this: public interface IRepository<T extends IEntity> And a Repository class that looks like this: public class Repository<T extends IEntity> implements IRepository<T> Now, from within the constructor of my Repository class, I'd like to be able to "divine" the exact type of T. For example, if I instantiated a repository like this: IRepository<MyClass> repo = new Repository<MyClass>(); I'd like to know that T is actually MyClass. This is trivial in C#, but obviously generics are a totally different beast in Java and I can't seem to find anything that would help me do this.

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  • Why has Foundation 4 made its grid classes less natural and readable?

    - by Brenden
    The Background I love responsive CSS grids. I hate Bootstrap's complex class names. I fell in love with Foundations human readable class names. The Problem With Foundation 4, they have changed four columns to large-4 small-4 columns and in my opinion this makes the HTML markup less clear. This style of CSS class names is exactly why I switched from Bootstrap to Foundation. The Question What advantage is gained by Foundation 4's Grid in making this change? It seems that you can have a different grid layout on smaller screens via media queries, but I can't think of a design that would require this. Note: I've been focused on native mobile development and therefore I may be missing out on recent best practices.

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  • runtime/compile time polymorphism

    - by dmadhavaraj
    Hi , In the below code , why b1.subtract() fails . Please explain me the reason ie., what happens in JVM while invoking that method . class Base { public void add() { System.out.println("Base ADD"); } } class Child extends Base { public void add(){ System.out.println("Child ADD"); } public void subtract() { System.out.println("Child Subtract"); } } class MainClass { public static void main(String args[]) { Base b1 = new Base(); Base b2 = new Child(); Child b3 = new Child(); b1.add(); b1.subtract(); // ?????????** b2.add(); b3.subtract(); } }

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  • Receive messages for derived types in MVVMLight

    - by Hrvoje
    Shouldn't this test pass: [TestMethod] public void derived_message_subscription() { bool handled = false; Messenger.Default.Register<GenericMessage<baseClass>>(this, true, (msg) => handled = true); Messenger.Default.Send(new GenericMessage<testClass>(new testClass())); Assert.IsTrue(handled); } public abstract class baseClass { } public class testClass : baseClass { } I have to receive all messages for classes that inherits from one base class. MVVMLight has bool property receiveDerivedMessagesToo in Register method, but it seems to me that it isn't working.

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  • Fastest/One-liner way to list attr_accessors in Ruby?

    - by viatropos
    What's the shortest, one-liner way to list all methods defined with attr_accessor? I would like to make it so, if I have a class MyBaseClass, anything that extends that, I can get the attr_accessor's defined in the subclasses. Something like this: class MyBaseClass < Hash def attributes # ?? end end class SubClass < MyBaseClass attr_accessor :id, :title, :body end puts SubClass.new.attributes.inspect #=> [id, title, body] What about to display just the attr_reader and attr_writer definitions?

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  • How Do I Select a `td` Element in a Row That Has a Checkbox That is Checked?

    - by Russ Bradberry
    I have a table that looks somethings like this: <table> <tr class="row even"> <td><input type="checkbox" /></td> <td class="name">foo</td> <td class="metric">22</td> </tr> ...etc What I want to do is get an array of all td.metric only in rows that have the checkbox checked. This didn't work out as expected: var ticks = $.map($("tr td input:checked td.metric"), function(v,i){ return ... });

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  • Does AsEnumerable() cache all result (LINQ)

    - by Akshay
    When we call a query operator on a sequence, a sequence-specific operator gets called. I mean if i call Where<>() operator on IEnumerable<>, the operator that will be called will be defined in Enumerable class and if it's called on IQueryable<>, the one defined in Queryable class will be called. Consider the operator Reverse, defined in the Enumerable class. If i want to call it on Iqueryable<> then I must use the AsEnumerable<>() operator to first convert it into IEnumerable<>. db.Countries.OrderBy(cntry=>cntry.CountryName).AsEnumerable().Reverse() But the Reverse operator got to have all records at the same time so that it can reverse them. In the above code do all the records get loaded in memory first and then the Reverse() operator is reversing it ?

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  • C# - Why can't I enforce derived classes to have parameterless constructors?

    - by FrisbeeBen
    I am trying to do the following: public class foo<T> where T : bar, new { _t = new T(); private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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  • Should we avoid to use Object as the input parameter/ output value of a method?

    - by developer.cyrus
    Take Java syntax as an example, though the question itself is language independent. If the following snippet takes an object MyAbstractEmailTemplate as input argument in the method setTemplate, the class MyGateway will then become tightly-coupled with the object MyAbstractEmailTemplate, which lessens the re-usability of the class MyGateway. A compromise is to use dependency-injection to ease the instantiation of MyAbstractEmailTemplate. This might solve the coupling problem to some extent, but the interface is still rigid, hardly providing enough ?exibility to other developers/ applications. So if we only use primitive data type (or even plain XML in web service) as the input/ output of a method, it seems the coupling problem no longer exists. So what do you think? public class MyGateway { protected MyAbstractEmailTemplate template; publoc void setTemplate(MyAbstractEmailTemplate template) { this.template = template; } }

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  • CSS Selector Issue

    - by YsoL8
    Hello html body .home blog logged-in div #wrapper div #page div .cats I have a problem with selecting unordered lists (i.e ul li.class-name class-name-number) at the above dom location in CSS. I am working with a wordpress theme. Basically could I have suggestions for the correct selector to use in order to influence this tag? I can provide a simplified html structure if it will help. I've tried a number of selectors along the lines of: (sometimes)#page (# or .)cats (sometimes)ul li(sometimes with class name) EDIT: I've tried the selectors suggested in the wordpress docs. Thanks!

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  • Can C++ Constructors be templates?

    - by Gokul
    Hi, I have non-template class with a templatized constructor. This code compiles for me. But i remember that somewhere i have referred that constructors cannot be templates. Can someone explain whether this is a valid usage? typedef double Vector; //enum Method {A, B, C, D, E, F}; struct A {}; class Butcher { public: template <class Method> Butcher(Method); private: Vector a, b, c; }; template <> Butcher::Butcher(struct A) : a(2), b(4), c(2) { // a = 0.5, 1; // b = -1, 1, 3, 2; // c = 0, 1; } Thanks, Gokul.

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  • Buffering db inserts in multithreaded program

    - by Winter
    I have a system which breaks a large taks into small tasks using about 30 threads as a time. As each individual thread finishes it persists its calculated results to the database. What I want to achieve is to have each thread pass its results to a new persisance class that will perform a type of double buffering and data persistance while running in its own thread. For example, after 100 threads have moved their data to the buffer the persistance class then the persistance class swaps the buffers and persists all 100 entries to the database. This would allow utilization of prepared statements and thus cut way down on the I/O between the program and the database. Is there a pattern or good example of this type of multithreading double buffering?

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  • indicate tuncation in ToolTipStatusLabel automatically

    - by harper
    I have a .NET application with a StatusStrip holding three ToolTipStatusLabels. The Text of the labels are filled from the application as they show the status. For some circumstances they can hold an empty text. When I resize the window, the ToolTipStatusLabels are hidden when they cannot be fit in the StatusStrip. I would like to have the text truncated when the label cannot be fit in the StatusStrip. The default behavior to hide the label makes it difficult to distinguish between empty text or hidden label. To indicate that the text is truncated automatically, this should be indicated with an ellipsis (...). How can this be done?

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