Why registering a generic type with one type parameter to Unity Container fails here?

Question

I am trying to register a generic type to unitycontainer via configuration file, as shown below in a simplified way.

However on the LoadConfiguration method call I get an error:

"The type name or alias IDataLoader`1[Bar] could not be resolved. Please check your configuration file and verify this type name."

This is the line I get my exception after:

IUnityContainer container = new UnityContainer().LoadConfiguration();

And those are my classes (in the assemblies same name as namespaces):

namespace FooBar.DataManager
{
    public interface IDataLoader<TSource>
    {
        void DoSomeWork(TSource source);
    }
}

namespace FooBar.DataManager.MyDataManager
{
    public class FooDataLoader : IDataLoader <Bar>
    {
      public void DoSomeWork(Bar source)
      {
        Console.WriteLine("Doing {0}", source.Name);
      }
    }
}

namespace FooBar.DomainModel
{
    public class Bar
    {
        string Name {get; set;}
    }

}

And this is the part how I register in the configuration file:

<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
        <alias alias="Bar" type="FooBar.DomainModel.Bar, FooBar.DomainModel" />
        <alias alias="IDataLoader`1" type="FooBar.DataManager.IDataLoader, FooBar.DataManager" />

    <container>
      <register type="IDataLoader`1[Bar]" mapTo="FooBar.DataManager.MyDataManager.DataLoader, FooBar.DataManager.MyDataManager" name="FooBarLoader" />
    </container>

</unity>

Can you please advise how should I register the IDataLoader generic type into unitycontainer? Or where I do my mistake? Thanks!

Your alias appears to try to alias a non-generic IDataLoader type. Have you tried <alias alias="IDataLoader'1" type="FooBar.DataManager.IDataLoader'1, FooBar.DataManager" /> ? (But with backticks instead of apostrophes... I can never get them to work in comments here...) — Jon Skeet
– Jon Skeet, Commented May 22, 2015 at 5:48
Hi Jon, yes I tried that.I am suspicious with the syntax whether I use it correctly or not to be honest. But I cannot see mistake. — pencilCake
– pencilCake, Commented May 22, 2015 at 5:56
Looking at msdn.microsoft.com/en-us/library/dn507491(v=pandp.30).aspx, I don't think you should have the backticks anywhere, in fact. It's not clear how aliases work with generics though... (As an aside, I haven't used Unity myself - if you're able to put together a short but complete example that we could easily use to reproduce the problem, that'd be great.) — Jon Skeet
– Jon Skeet, Commented May 22, 2015 at 5:58

Jon Skeet · Accepted Answer · 2015-05-22 06:32:16Z

1

Looking at the documentation again, I think you want to use backticks or square brackets for the open type in the alias target, but not for the closed type or the alias itself:

<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
    <alias alias="Bar" type="FooBar.DomainModel.Bar, FooBar.DomainModel" />
    <alias alias="IDataLoader" type="FooBar.DataManager.IDataLoader`1, FooBar.DataManager" />

    <container>
      <register type="IDataLoader[Bar]" mapTo="FooBar.DataManager.MyDataManager.DataLoader, FooBar.DataManager.MyDataManager" name="FooBarLoader" />
    </container>
</unity>

edited May 22, 2015 at 6:32

answered May 22, 2015 at 6:02

Jon Skeet

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3 Comments

pencilCake Over a year ago

Jon, did you put the backtick end of the assembly name by purpose? (FooBar.DataManager`1) Does not that remarks the generic type and the number of parameters that is bound to type, but not the assembly?

Jon Skeet Over a year ago

@pencilCake: Nope, that was a stupid typo - fixed now, thanks. Whether it helps will be a different matter...

Jon Skeet Over a year ago

@jlvaquero: Sorry, I don't quite understand your comment. Your other answer suggests that alias is just a string replacement - I don't believe it is.

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