Auto-setting property values with Unity dependency injection

Question

I have a context interface with a few properties that I would like unity to auto-set when the interface is resolved. Here is the interface and class.

public interface IAdapterContext
{
    IFoo Foo { get; }

    IBar Bar { get; }
}

public class AdapterContext
{
    public IFoo Foo { get; set; } 

    public IBar Bar { get; set; }
}

The interface resolves to the class successfully, but all of the instance members are null. The corresponding instance member interfaces are registered.

One solution is to add a constructor in the class that receives all of the values, but I would rather not do this since I also want the default constructor for ease of testing. Having both a default and a non-default just to satisfy unity doesn't sit well with me.

Another solution is to use the InjectionProperty class, but this overall a more complex solution than just adding a constructor. It also decouples the property names from the actual class, which could break during refactoring.

Does unity support auto-setting property values for an implemented interface, or does it always need to be done through the constructor/InjectionProperty?

Use nameof(SomeType.TargetProperty) to avoid breakage when refactoring if using the InjectionProperty route. — Josh Gust
– Josh Gust, Commented Aug 16, 2018 at 15:16

Rafal · Accepted Answer · 2014-06-24 18:53:53Z

3

There is a Dependency attribute that you can use to mark properties that you want to inject.

public class AdapterContext
{
    [Dependency]
    public IFoo Foo { get; set; } 

    [Dependency]
    public IBar Bar { get; set; }
}

I would not recommend this solution. I always go with constructor injection and configure dedicated container for test that contains mocks of dependencies.

answered Jun 24, 2014 at 18:53

Rafal

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1 Comment

Ryan Burbidge Over a year ago

Marking as the answer, but still used the constructor based solution. Thanks for the help!

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