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New Post: Constructor parameter injection

omar_gamil — Sun, 26 May 2013 07:58:57 GMT

Hello,

Can customize AppStart_MefContribMVC3 to add custom exported values ?

I have this class

    [Export(typeof(IUserRepository))]
    public class UserRepository : GenericRepository<User>, IUserRepository
    {
        [ImportingConstructor]
        public UserRepository(string connectionString)
            : base(connectionString)
        {

        }
    }
}

how can I add this in AppStart_MefContribMVC3 ?

ComposeExportedValue("connectionString", "connection string value");

Thank you

New Post: MefContrib: Interception.Unity + Integration.Unity

rickyno — Wed, 27 Mar 2013 20:55:41 GMT

Hi
I'm trying to achieve something but can't get my head around how to do it. Basically I have multiple interfaces implementations marked with a custom Export attribute, so they get picked up by MEF, and the catalog in which they are is registered in a UnityContainer. The constructor of these implementations have the ImportingConstructor so unity can inject the parameters when MEF creates a requested part. This bit works just fine.

My problem is, I need to setup interception on certain types in the catalog, and I'm using Unity interception and this cannot be changed in my scenario. Here how it was configured before using MEF to load them:

unityContainer.RegisterType<IAuthenticationService, AuthenticationService>().Configure<Interception>().SetInterceptorFor<IAuthenticationService>(new InterfaceInterceptor());

My new code to load these using MEF:

DirectoryCatalog directoryCatalog = new DirectoryCatalog(".");
FilteredCatalog servicesCatalog = new FilteredCatalog( /* filtering on a metadata of the custom export attribute */ );

// servicesCatalog is properly populated at this point
// TODO: need to setup interception, as in the previous code block, on the servicesCatalog parts, without knowing the interface and implementation names (IAuthenticationService, AuthenticationService) except by looking at the ExportDefinitions. So I'm Stuck Here!

unityContainer.EnableCompositionIntegration();
unityContainer.RegisterCatalog(servicesCatalog);

// resolving a known interface here, loaded from MEF catalog above, works perfectly fine, Unity injects construct parameters to that instance being constructed by MEF, so my 2-way integration is fine.

But now that all I have is a FilteredCatalog with ComposableParts, I simply don't know how to adapt my interception code using MefContrib.Interception.Unity, and I can't seem to find any documentation or samples on this matter.

Any help would greatly be appeciated.

New Post: MVC4

JayKnowsit — Thu, 01 Nov 2012 05:21:14 GMT

Is there Mefcontrib.MVC4? Or can some explain how I can use the Mefcontrib.MVC3 for the MVC4 application?

New Post: MEF Exported class with Unity dependency not composed

bstabile — Thu, 18 Oct 2012 19:08:34 GMT

Robert,

It this something like what you want?

(Note that the CompositionContainer is resolved from Unity BEFORE ComposeParts is called)

    [TestClass]
    public class MefUnityIntegrationTests
    {

... 
        [TestMethod]
        public void BasicMefUnityIntegrationTest()
        {
            var unityContainer = new UnityContainer();
            TypeRegistrationTrackerExtension.RegisterIfMissing(unityContainer);
 
            unityContainer.RegisterType<IUnityThing, UnityThing>();
 
            var catalog = new AssemblyCatalog(typeof(MefUnityIntegrationTests).Assembly);
            unityContainer.RegisterCatalog(catalog);
            var mefContainer = unityContainer.Resolve<CompositionContainer>();
            mefContainer.ComposeParts(this);
 
 
 
            foreach (var plugin in MyPlugins)
            {
                this.TestContext.WriteLine("Plugin.Name = {0}  Plugin.Thing.Name = {1}", plugin.Name, plugin.Thing.Name); 
            }
        }
 
        [ImportMany(typeof(IPlugin))]
        public List<IPlugin> MyPlugins { get; set; }
 
    }
 
    public interface IPlugin
    {
        string Name { get; }
        IUnityThing Thing { get; set; }
    }
 
    [Export(typeof(IPlugin))]
    public class PluginA : IPlugin
    {
        public string Name { get { return "PluginA"; } }
 
        [Import]
        public IUnityThing Thing { get; set; }
    }
 
    [Export(typeof(IPlugin))]
    public class PluginB : IPlugin
    {
        public string Name { get { return "PluginB"; } }
 
        [Import]
        public IUnityThing Thing { get; set; }
    }
 
    public interface IUnityThing
    {
        string Name { get; }
    }
 
    public class UnityThing : IUnityThing
    {
        public string Name { get { return "UnityThing"; } }
    }

In any case, this particular example works for me, producing the following output...

Plugin.Name = PluginA  Plugin.Thing.Name = UnityThing
Plugin.Name = PluginB  Plugin.Thing.Name = UnityThing

Regards,

Ben

New Post: MEF Exported class with Unity dependency not composed

bertnz — Tue, 10 Jul 2012 06:11:03 GMT

Hi all,

I am quite new to this so I may be doing something real dumb but here goes.

Have been using a MEF directory cataglog and a CompositionContainer to populate a list of objects and runtimes (based on the components in my directory.

It goes something like this

[ImportMany(typeof(IPlugin))]
public List<IPlugin> MyPlugins { get; set; }

var catalog = new DirectoryCatalog("PluginFolder");
var container = new CompositionContainer(catalog);
container.ComposeParts(this);

It was working perfectly fine and populating my MyPlugins property with my 2 plugins.

I have since added unity into my solution and have add a dependency to one of my plugin classes. As soon as I do this it stops appearing in my list of plugins. No error occurs - it is like my plugin has vanished as soon as it has the dependency added.

I have registered my catalog against my unity container (which has already been fully registered/configured)

var catalog = new DirectoryCatalog("PluginFolder");
unityContainer.RegisterCatalog(catalog);
var container = new CompositionContainer(catalog);
container.ComposeParts(this);

The plugin itself has its Unity-owned dependency specified like so

  [Import]
  public IUnityHostedThing MyThing { get; set; }

I have also tried the constructor injection like so

[ImportingConstructor]
public PluginA(IUnityThing thing)
{
    this.Mything = thing;
}

Neither approach works and either way the class no longer gets returned by the composition container stuff.

Any ideas? I haven't seen a good up to date example of this working with any actual implementations online - are there any?

cheers,
Robert

New Post: New NuGet Version, Please? :)

MichaelDBang — Tue, 28 Feb 2012 21:29:12 GMT

Can we get a new version of this library in NuGet that has updated dependencies on Unity and also an assembly version for Silverlight? :)

Thank you,

Michael

New Post: GenericContractTypeMapping is a sealed class so it's not possible to derive

pwlodek — Sat, 18 Feb 2012 19:07:40 GMT

Can you please provide sample solution we can both work on ?

New Post: GenericContractTypeMapping is a sealed class so it's not possible to derive

kavand — Thu, 16 Feb 2012 10:46:00 GMT

@Piotr I follow that blog post for my MVC3 application. But I get this error:

The IControllerFactory 'MefContrib.Web.Mvc.CompositionControllerFactory' did not return a controller for the name 'Home'

Can you guide me please?

New Post: MefContrib.MVC3 and Lazy imports on controllers

maartenba — Thu, 16 Feb 2012 08:21:30 GMT

Can you post a small repro project so I can investigate?

New Post: MefContrib.MVC3 and Lazy imports on controllers

kavand — Thu, 16 Feb 2012 07:08:31 GMT

I get same error too. Can everybody help please???

New Post: ImportCardinalityMismatchException - Requested type has more than one instance

dm_nazaryev — Tue, 07 Feb 2012 15:48:49 GMT

This is confirmed!

It's an ugly limiting trick, but still better than nothing.

There is no integration between MEF and UNITY achived. In this solution MEF is used strictly as a DI container and Unity is used for interception. In fact, MefContrib.dll is not required here.

New Post: ImportCardinalityMismatchException - Requested type has more than one instance

k_kaszuba — Tue, 07 Feb 2012 15:28:58 GMT

There is also another option,if you only want to use AOP policy injection of Unity. Call container.BuildUp<InterfaceType> for each instance imported by MEF. The condition for this to work is that you don't register the MEF catalog into the unity container.

New Post: ImportCardinalityMismatchException - Requested type has more than one instance

dm_nazaryev — Mon, 23 Jan 2012 21:42:23 GMT

Guys, is there a way to use Unity's Policy Injection when I resolve multiple registrations (which are done through MEF) by a UnityContainer?

unityContainer.Resolve<IEnumerable<IMyInterface>>() returns an IEnumerable<IMyInterface>, but policy injection into each instance of IMyInterface configured in Unity is not done.

Thanks.

New Post: Generic method exports

pwlodek — Mon, 23 Jan 2012 09:17:49 GMT

No, exporting generic methods is not yet supported by MEFContrib. You can try with MEF2 preview bits, they have nice generic support baked in.

/Piotr

New Post: MefContrib dll should be strong named

thecodejunkie — Fri, 20 Jan 2012 22:05:28 GMT

The shortest answer I can give is that this will often lead to an upgrade path nightmare. We sign ours, so our 3rd party dependencies needs to sign their (many of which are OSS themselves).. we start getting binding redirects everywhere, multiple version of the same assembly.. for the most part I just don't see the benefit.

If you have a real need (which I can understand because of corporate policies etc) then you can easily download the source, build and sign it yourself. That is the beauty of open-source. It doesn't really matter if we sign it or if you sign it, right? The only reason you need this to be signed is because your own assembly is signed, not because you really need to make sure that the mef contrib assemblies originates from a trusted source.

Unless I am missing something here ?

Thanks

/Andreas

New Post: Generic method exports

seanberg — Fri, 20 Jan 2012 16:49:40 GMT

Can anyone tell me if this type of generic composition is supported?

New Post: MefContrib dll should be strong named

seanberg — Fri, 20 Jan 2012 16:47:54 GMT

Any thoughts on this?

New Post: ImportCardinalityMismatchException - Requested type has more than one instance

dm_nazaryev — Tue, 17 Jan 2012 19:11:25 GMT

unityContainer.Resolve<IEnumerable<IMyInterface>>() works. Thanks for the hint!

However, the Unity's policy injection mechanism does not work with this approach, which was the whole point of my exercise.

I've got the following config file:

    <container name="PolicyInjection">
      <interception>
        <policy name="MyTestPolicy">
          <matchingRule name="TypeMatch" type="TypeMatchingRule">
            <constructor>
              <param name="typeName" value ="IMyInterface"/>
            </constructor>
          </matchingRule>
          <matchingRule name="MemberNameMatch" type="MemberNameMatchingRule">
            <constructor>
              <param name="nameToMatch" value="DoSomething"/>
            </constructor>
          </matchingRule>
          <callHandler name="Handler" type="TestCallHandler">
            <lifetime type="ContainerControlledLifetimeManager"/>
          </callHandler>
        </policy>
      </interception>
    </container>

Policy injection works when I have a single implementation of IMyInterface and do unityContainer.Resolve<IMyInterface>();

But if I have multiple implementations of IMyInterface (as in the original post) and I do unityContainer.Resolve<IEnumerable<IMyInterface>>() the policy injection does not happen.

unityContainer.BuildUp<IMyInterface>(myInstance) does not help either - it also throws the exception in the title.

Any ideas?

New Post: ImportCardinalityMismatchException - Requested type has more than one instance

pwlodek — Mon, 16 Jan 2012 08:37:49 GMT

Hi,

Yes, this scenario is supported. ResolveAll() method is not what you want to use as it returns named instance, and this is not supported in the integration layer. What you can do is you can resolve IEnumerable of IMyInterface like this:

unityContainer.Resolve<IEnumerable<IMyInterface>>()

You can also find interesting the following reading http://pwlodek.blogspot.com/2010/05/lazy-and-ienumerable-support-comes-to.html

When resolving types by name, Unity cannot derive information about your metadata key named "Name". You have to pass contract name in the export attribute. Then, you should be fine resolving from Unity using that contract name.

Hope this helps!

Piotr

New Post: ImportCardinalityMismatchException - Requested type has more than one instance

dm_nazaryev — Fri, 13 Jan 2012 19:27:39 GMT

Is there a way to resolve multiple registrations of the same type (which were exported through MEF) by a UnityContainer?

UnityContainer.ResolveAll<IMyInterface>() returns an empty IEnumerable.

UnityContainer.Resolve() throws the exception in the title.

I would expect to be able to do exports in MEF something like this:

[Export(typeof(IMyInterface))]
[ExportMetadata("Name", "MyType1")]
public class MyType1 : IMyInterface {}

[Export(typeof(IMyInterface))]
[ExportMetadata("Name", "MyType2")]
public class MyType2 : IMyInterface {}

And then resolve the objects either through UnityContainer.ResolveAll<IMyInterface>(); or UnityContainer.Resolve<IMyInterface>("MyType1");