Unity constructor injection with other parameter

问题:

I have a class with a constructor that looks like the following:

public BatchService(IRepository repository, ILogger logger, string user)

In my DI bootstrapper class, I have the following RegisterType command:

.RegisterType<BatchService>(
    new InjectionConstructor(
        new ResolvedParameter<IRepository>("SomeRepository"), 
        new ResolvedParameter<ILogger>("DatabaseLogger")))

In my client code, I want to instantiate BatchService as follows:

BatchService batchService = DIContainer.Resolve<BatchService>()

As you can see, I have a string parameter called user as part of the constructor to BatchService that is not part of the DI logic. How should I best handle this situation if I need to use user in the BatchService class?

回答1:

Please don't abuse Unity as a ServiceLocator.

If you want to create objects that need runtime parameters use a factory. You can even drop the act of implementing that factory by either using the Unity version of Typed Factories or let Unity generate factory delegates for you.

回答2:

You can use ParameterOverride:

BatchService batchService = 
DIContainer.Resolve<BatchService>(new ParameterOverride("user", valueForUser));

回答3:

First of all it's not good idea mix ILogger with business logic. You can create ILogger directly in BatchService or resolve thru [Dependency] attribute. DI it's not panacea, business object creation shouldn't depend from ILogger

Use new InjectionParameter<string>("user") Take a look please Registering Injected Parameter and Property Values for more details