StructureMap Beginner | Property Injection

Question

Part of this question was already asked here : structuremap Property Injection but the answer was never given.

With StructureMap, is it possible to do Property Injection such that

class SomeController : Controller
{
 public IService Service
 {
  get;
  set;
 }
}

gets injected properly? I am a

Answer 1

StructureMap supports setter/property injection. So you could do the following:

public class SomeController : Controller
{
    [SetterProperty]
    public IService Service { get; set; }
}

and then:

ObjectFactory.Initialize(x =>
{
    x.For<IService>()
     .Use<ServiceImpl>();
});

or if you don't like the idea of cluttering your controllers with StructureMap specific attributes you could configure it like this:

ObjectFactory.Initialize(x =>
{
    x.For<IService>()
     .Use<ServiceImpl>();

    x.ForConcreteType<SomeController>()
     .Configure
     .Setter<IService>(c => c.Service)
     .IsTheDefault();
});

Also note that property injection is suitable in scenarios where the presence of this property is not compulsory for the correct functioning of the controller. For example think of a logger. If the consumer of the controller doesn't inject any specific implementation of a logger into the property the controller still works it's just that it doesn't log. In your case you are using a service and I would use constructor injection if your controller actions depend on this service. So the question you should ask yourself is: will my controller crash when I call some its action if this property is null? If the answer to this question is yes then I would recommend constructor injection. Also when you use a constructor injection you force the consumer of this controller to specify an implementation because he cannot obtain an instance of the controller without passing a proper service in the constructor.

Answer 2

To inject dependencies for all properties of a certain type, use the SetAllProperties method as part of the initialization of your ObjectFactory:

ObjectFactory.Initialize(x =>
{
   x.SetAllProperties(x => x.OfType<IService>());
});

It is also possible to define policies for setter injection, see this post.