MEF field imports not being resolved

Question

I have MEF/Prism 4 project for which I can resolve imports via the ImportingConstructor, but not via field imports in the same class.

In the sample code below, myDataService is correctly resolved in the constructor. But _myDataServiceFieldImport isn't resolved, despite the Import attribute. Same result whether it's a field or property.

Anything obvious I'm missing here?

[ModuleExport(typeof(TestModule))] 
public class TestModule : IModule
{
    private IMyDataService _myDataService;

    [Import]
    private IMyDataService _myDataServiceFieldImport;

    [ImportingConstructor]
    public TestModule(IMyDataService myDataService)
    {
        _myDataService = myDataService;
    }
}

[PartCreationPolicy(CreationPolicy.Shared)]
[Export(typeof(IMyDataService))]
public class MyDataService : IMyDataService 
{

}

Answer 1

原来只是我很笨-我在检查构造函数中的属性/字段值，而构造函数完成后才可以解析它们。

Answer 2

将访问修饰符从私有更改为公共，然后检查是否可行。