Startup.cs
public void ConfigureServices(IServiceCollection services){
/*boilerplate's default bindings*/
services.AddTransient<IDummy,Dummy>(p => new Dummy()
{
name = "from injection"
});
}
HomeController.cs
public IActionResult Index(IDummy dummy){
var test = dummy.name;
return this.View(HomeControllerAction.Index);
}
例外：
ArgumentException: Type
‘Presentation.WebUI.Controllers.IDummy’ does not have a
default constructor
你能告诉我我做错了什么吗？
解决方法
当框架默认使用构造函数注入时,您正尝试对Action执行注入.
参考：Dependency Injection and Controllers
ASP.NET Core’s built-in support for constructor-based dependency
injection extends to MVC controllers. By simply adding a service type
to your controller as a constructor parameter,ASP.NET Core will
attempt to resolve that type using its built in service container.
public class HomeController : Controller {
IDummy dummy;
public HomeController(IDummy dummy) {
this.dummy = dummy
}
public IActionResult Index(){
var test = dummy.name;
return this.View(HomeControllerAction.Index);
}
}
ASP.NET Core MVC controllers should request their dependencies
explicitly via their constructors. In some instances,individual
controller actions may require a service,and it may not make sense to
request at the controller level. In this case,you can also choose to
inject a service as a parameter on the action method.
Action Injection with FromServices
Sometimes you don’t need a service for more than one action within
your controller. In this case,it may make sense to inject the service
as a parameter to the action method. This is done by marking the
parameter with the attribute [FromServices] as shown here:
public IActionResult Index([FromServices] IDummy dummy) {
var test = dummy.name;
return this.View(HomeControllerAction.Index);
}
