[Activate] does not work on Controllers in beta4

[Tragetaschen]

The following two lines work in a tag helper, but give a stack trace when in a controller:

[Activate]
private IHostingEnvironment hostingEnvironment{ get; set; }

That stacktrace is

InvalidOperationException: The property 'hostingEnvironment' on controller '*.Controllers.somecontroller' cannot be activated.

    Microsoft.AspNet.Mvc.DefaultControllerFactory.CreateActivateInfo(PropertyInfo property)
    System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
    System.Linq.Buffer`1..ctor(IEnumerable`1 source)
    System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
    Microsoft.Framework.Internal.PropertyActivator`1.GetPropertiesToActivate(Type type, Type activateAttributeType, Func`2 createActivateInfo)
    Microsoft.AspNet.Mvc.DefaultControllerFactory.GetPropertiesToActivate(Type type)
    System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
    Microsoft.AspNet.Mvc.DefaultControllerFactory.ActivateProperties(Object controller, ActionContext context)
    Microsoft.AspNet.Mvc.DefaultControllerFactory.CreateController(ActionContext actionContext)
    Microsoft.AspNet.Mvc.Core.ControllerActionInvoker.CreateInstance()
    […]

[rynowak]

This is a design change - [Activate] is for context items like ActionContext. Use [FromServices] in a controller to access a service (or take it as a constructor parameter).

We have some changes planned for the current milestone to make this consistent across taghelpers/controllers

[Tragetaschen]

Makes sense. It looks like view components are working like tag helpers right now, right?

It might be a different issue, but I'm trying to get an IApiDescriptionGroupCollectionProvider into my Controller. In my ViewComponent, I can still use [Activate] and it works like before. In the controller, though, the situation is:

• Constructor parameter: works
• [Activate]: Cannot activate exception with stack trace
• [FromServices]: property remains null

[rynowak]

[FromServices] on a controller property is expected to work in beta4 - is it a public get/set property?

[Tragetaschen]

Ah, that's it. I still had this specified as a private property. That worked with [Activate] and still works ViewComponents and TagHelpers.

[danroth27]

Note that we plan to clean up the naming of Inject vs Activate vs FromService. See #2151.