在ASP.NET 5中使用DI调用构造函数时解析依赖性

Question

The web seems flooded with examples on how to use DI with ASP.NET 5 but not one of the examples shows how to call a constructor and resolve dependencies.

The following is just one of many cases: http://social.technet.microsoft.com/wiki/contents/articles/28875.dependency-injection-in-asp-net-vnext.aspx

But what happens if I want to do the following:

var todoRepository = app.ApplicationServices.GetRequiredService<ITodoRepository>();
ToDoController controller = new TodoController(todoRepository);

Presumably this can be shorted to something like...

.Get<TodoController>()

Like you can in Ninject.

Can someone explain how this can be done?

Answer 1

First, you'll want to make sure the class you want to construct is registered with the DI container. (Given your example of a controller, it probably already is thanks to the MVC framework.)

There's several ways to do this, the most basic of which is registering a Transient. Note this needs to be done in the ConfigureServices stage of your Startup class.

services.AddTransient<ToDoController>();

Once you have it registered, you can resolve it just like you would any other service:

app.ApplicationServices.GetRequiredService<ToDoController>();

For more information, I'd recommend Victor Hurdugaci's blog on Dependency Injection in ASP.NET vNext . It was written for alpha, but it looks like it's still accurate.