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POMEF Property Allways Returning Null
 

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  1. POMEF Property Allways Returning Null
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    <p><strong>Original Source Code</strong></p> <p>I've got a simple business object in my BusinessObjects.dll file:</p> <pre><code>namespace BusinessObjects { public class MyClass { public MyClass() { DateTime = DateTime.Now; } public DateTime DateTime { get; set; } } } </code></pre> <p>In my SharedUI.dll I've got this "Context-provider" class, that I use to hold a referece to the currently selected MyClass - remember this is a simplyfied example :)...</p> <pre><code>namespace SharedUI { public class AppContext { [Export] public MyClass SelectedMyClass { get; private set; } public void SetupContext(MyClass myClass) { SelectedMyClass = myClass; } public static AppContext Context { get { if (context == null) { context = new AppContext(); } return context; } } private static AppContext context; } } </code></pre> <p>My MefTest.exe has this class:</p> <pre><code>namespace MefTest { public class Program { [Import] public MyClass MyClass { get; set; } private void Compose() { var ventSystem = new MyClass(); AppContext.Context.SetupContext(ventSystem); var executingAssembly = new AssemblyCatalog(Assembly.GetExecutingAssembly()); var contextAssembly = new AssemblyCatalog(Assembly.LoadFile(string.Format(@"{0}\SharedUI.dll", Environment.CurrentDirectory))); var catalog = new AggregateCatalog(executingAssembly, contextAssembly); var container = new CompositionContainer(catalog); container.ComposeParts(this); } private void Run() { Compose(); // MyClass is always null in the next line? Console.WriteLine(MyClass.DateTime.ToString()); Console.ReadKey(); } private static void Main(string[] args) { var p = new Program(); p.Run(); } } } </code></pre> <p>I'm a MEF rookie so please bear with me :)</p> <p><strong>UPDATED Source Code with suggestions from Daniel Plaisted</strong></p> <p>MyClass source is the same...</p> <p>SharedUI.dll now looks like this:</p> <pre><code>namespace SharedUI { [Export] public class AppContext { [Export(typeof(MyClass))] public MyClass SelectedMyClass { get; private set; } public void SetupContext(MyClass myClass) { SelectedMyClass = myClass; } } } </code></pre> <p>MefTest.exe now looks like this:</p> <pre><code>namespace MefTest { public class Program { [Import] public MyClass MyClass { get; set; } [Import] public AppContext AppContext { get; set; } private void Compose() { var executingAssembly = new AssemblyCatalog(Assembly.GetExecutingAssembly()); var contextAssembly = new AssemblyCatalog(Assembly.LoadFile(string.Format(@"{0}\SharedUI.dll", Environment.CurrentDirectory))); var catalog = new AggregateCatalog(executingAssembly, contextAssembly); var container = new CompositionContainer(catalog); container.ComposeParts(this); var myClass = new MyClass(); AppContext.SetupContext(myClass); } private void Run() { Compose(); // AppContext.SelectedMyClass is NOT null in the next line... which is good I guess :) Console.WriteLine(AppContext.SelectedMyClass.DateTime.ToString()); // MyClass is always null in the next line? Console.WriteLine(MyClass.DateTime.ToString()); Console.ReadKey(); } private static void Main(string[] args) { var p = new Program(); p.Run(); } } } </code></pre> <p>What am I doing wrong since I can't get it working?</p>
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    1. USKenneth Kryger Sørensen
    1. USKenneth Kryger Sørensen
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    1. COHave you verified that it loads the `GUI` into the AssemblyCatalog?
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      1. USJonas Van der Aa
    2. CO@Jonas: What do you mean by "GUI"? Is it the project containing the Program-class, AppContext-class or MyClass-class...?
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      1. USKenneth Kryger Sørensen
    3. COI'm sorry, I'm mixing up 2 different SO questions :) I mean the AppContext class. Have you verified that it is being loaded by MEF?
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      1. USJonas Van der Aa
 

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