Unity.WebAPI | simple integration of Microsoft 's Unity IoC container | Dependency Injection library

You will need the Unity.AspNet.WebApi adapter to configure your ApiControllers.

Careful you don't mix up packages. Some of those are not by the same project owner (Unity.Mvc5, Unity.WebAPI). I haven't used those so I can't comment on its suitability.

I have a example https://github.com/jasenhk/MovieStar from another answer that uses Unity v5.10 and Unity.MVC as well as Unity.AspNet.WebApi.

Here is the packages.config

You are missing the [TestClass] attribute on the test class (assuming your are using MSTest framework). Test classes need to have an empty default constructor or no constructors at all.

For setting up the tests you can either arrange it the way that you

1. Manually create the required instances or
2. Use a mocking framework or
3. Do the same initializations just like in your application regarding dependency injection, and then resolve the instances as required

Maybe you also want to take a look, at the Arrange-Act-Assert pattern for unit tests: (see http://defragdev.com/blog/?p=783)

Also keep in mind, that you rather want to test the code and not the DI framework.

If you are in control of the services then refactor the interfaces to expose the desired members

Check to make sure that all dependencies for the object graphs have been registered so that they can be resolved correctly.

You are most likely missing a dependency registration.

For TransactionService, you are passing/injecting the implementations in the constructors

the issue seems to originate from your registration call, when registering the same type multiple times with unity, the last registration call wins, in this case, that will be data access object for whoever user logs-in last. Unity will take that as the default registration, and will create instances that have the connection to that user's database.

The SessionLifetimeManager is there to make sure you get only one instance of the objects you resolve under one session.

One option to solve this is to use named registration syntax to register the data-access types under a key that maps to the logged-in user (could be the database name), and on the resolve side, retrieve this user key, and use it resolve the corresponding data access implementation for the user

I figured it out. Just like the error message says, I was trying to inject the DbContext in a non Http Request context at the time of application initialization. It works fine if I do it as shown below, without trying to configure the "InjectionConstructor" inside RegisterType for Repositories. It successfully injects a new instance of DbContext in the repository every request. Seems like you can't use InjectionConstructor for Types that are registered with "PerRequestLifetimeManager".

Many hours later I discovered that this error only appears on my default route and only on my dev machine. It was probably doing it all along and I assumed that something had changed after I re-checked out the code.

What is a word for this?

Rather than using a strategy or facade to solve this, a better solution would be to redesign your interfaces to be unique per controller. Once you have a unique interface type, your DI container will automatically inject the right service into each controller.

Use a generic interface.

Since I had stored a copy of my service with my entity's DBContext it was failing because it was being used by multiple threads. The fix was to new it up each time because it had originally came from a Unity DI resolver method and the entity doesn't get newed up each time the stored service and its methods are called.

Its unknown if the current context can be cleared up a different or better way to make it perform faster when finished with a specific use case scenario in a particular web api thread or end point instead of newing it up in each method call of the saved service.

Solution every time its stored in a static variable and reused on each method: