Service bound multiple times using ninject.extensions.conventions

问题

When using ninject conventions to bind all implementations of several interfaces I got the following problem:

public interface IServiceA { }
public interface IServiceB { }

public class Service : IServiceA, IServiceB { }

public class FooA
{
    public Foo(IEnumerable<IServiceA> a)
    {
       // a has 2 instances of Service
    }  
}

public class FooB
{
    public Foo(IEnumerable<IServiceB> b)
    {
       // b has 2 instances of Service
    }  
}

// ...
kernel.Bind(x => x
    .FromThisAssembly()
    .SelectAllClasses().InheritedFrom<IServiceA>().
    BindAllInterfaces());

kernel.Bind(x => x
    .FromThisAssembly()
    .SelectAllClasses().InheritedFrom<IServiceB>().
    BindAllInterfaces());

var a = new FooA(kernel.GetAll<IServiceA>());
var b = new FooB(kernel.GetAll<IServiceB>());

How should I configure the bindings in order to get only a single instance of Service ninjected?

回答1:

Most likly your conventions is not good if there is a component that can be in two of them. But it is impossible to tell from such a abstract scenario. You should think about that, E.g. use naming conventions:

kernel.Bind(x => x
.FromThisAssembly()
.SelectAllClasses().EndingWith("Service").
BindAllInterfaces());

or introduce a base interface:

kernel.Bind(x => x
.FromThisAssembly()
.SelectAllClasses().InheritedFrom<IService>().
BindAllInterfaces());

or introduce an attribute, select by namespace, .... There are many ways. An other option is to select the classes in two steps:

kernel.Bind(x => x
.FromThisAssembly().SelectAllClasses().InheritedFrom<IServiceA>()
.Join().FromThisAssembly().SelectAllClasses().InheritedFrom<IServiceB>().
BindAllInterfaces());

If the service types are configured differently you can Exclude the special case in one of the bindings:

kernel.Bind(x => x
.FromThisAssembly().SelectAllClasses().InheritedFrom<IServiceA>()
.Exclude<Service>().
BindAllInterfaces());

来源：https://stackoverflow.com/questions/19271097/service-bound-multiple-times-using-ninject-extensions-conventions

标签

.net

ninject