@onclick and other bindable targets not been parsed properly in Razor Class Libraries (.Net 5.0 Preview 7)

[Valks]

Describe the bug

It seems in RCL's that the parser (both intellisense and compiler) doesn't recognize most of the bind functions, i.e. @onclick...

To Reproduce

• Create a new Razor Class Library .Net 5.0 Preview 7
• Create a new Razor page and add a control, i.e. input
• Try to add an @onclick event. Intellisense won't highlight, it'll compile but fail on run.

Exceptions (if any)

No exceptions given, except when running trying to run:

warn: Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer[100]
      Unhandled exception rendering component: InvalidCharacterError: Failed to execute 'setAttribute' on 'Element': '@onclick' is not a valid attribute name.
System.InvalidOperationException: InvalidCharacterError: Failed to execute 'setAttribute' on 'Element': '@onclick' is not a valid attribute name.
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.InvokeRenderCompletedCallsAfterUpdateDisplayTask(Task updateDisplayTask, Int32[] updatedComponents)
fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
      Unhandled exception in circuit 'JQJPdqGZuuLbseMpJYmSZQEgBgi2HfsoGmzRKhE1O5Y'.
System.AggregateException: One or more errors occurred. (InvalidCharacterError: Failed to execute 'setAttribute' on 'Element': '@onclick' is not a valid attribute name.)
 ---> System.InvalidOperationException: InvalidCharacterError: Failed to execute 'setAttribute' on 'Element': '@onclick' is not a valid attribute name.
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.InvokeRenderCompletedCallsAfterUpdateDisplayTask(Task updateDisplayTask, Int32[] updatedComponents)
   --- End of inner exception stack trace ---

Further technical details

• ASP.NET Core version
  .Net 5.0 Preview 7
• Include the output of dotnet --info

.NET SDK (reflecting any global.json):
 Version:   5.0.100-preview.7.20366.6
 Commit:    0684df3a5b

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19041
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.100-preview.7.20366.6\

Host (useful for support):
  Version: 5.0.0-preview.7.20364.11
  Commit:  53976d38b1

.NET SDKs installed:
  3.1.100 [C:\Program Files\dotnet\sdk]
  3.1.400-preview-015203 [C:\Program Files\dotnet\sdk]
  5.0.100-preview.7.20366.6 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview7.19365.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-preview.7.20365.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview7-27912-14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-preview.7.20364.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview7-27912-14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-preview.7.20366.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
  https://aka.ms/dotnet-download

• The IDE (VS / VS Code/ VS4Mac) you're running on, and it's version
  VS 2019 16.7.0 Preview 6.0

[Valks]

In my main project (server-side, and WASM) the bindings are working correctly.

[mkArtakMSFT]

Thanks for contacting us.
It looks like you may be missing reference to the Microsoft.AspNetCore.Components.Web using.

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[Valks]

@mkArtakMSFT Thanks for the feedback. That was my first thought that there was a reference issue but I have Microsoft.AspNetCore.Components.Web (see below).

(Don't mind the line edit marker, I just fixed the spacing).

[Valks]

I noticed in a separate project I have that it doesn't have a reference to Microsoft.AspNetCore.Components and that project works. I'll give it a try and let you know if that solves the problem.

[Valks]

Ok figured it out, _Imports.razor was missing a @using statement: @using Microsoft.AspNetCore.Components.Web