Docs for the Component Tag Helper (or how to send a string parameter)

[mrlife]

[EDIT by guardrex to note that this issue can be worked with #17210]

I'm unable to find the docs for the Component Tag Helper, i.e. <component>. I'm trying to send a string as a parameter but getting a build error. I know you can send an integer, per this page of the docs, but I can only send a string if it's in a variable. Here is the code and error.

Code

<component type="typeof(ColorfulCheckbox)"
	   render-mode="Server"
	   param-Color="blue" />

Error

The name 'blue' does not exist in the current context (CS0103)

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Document Details

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• ID: fcac856a-7cdc-41fb-b7ea-7c5583916019
• Version Independent ID: b6f9f287-407a-6036-10b0-4bc13cfade17
• Content: Integrate ASP.NET Core Razor components into Razor Pages and MVC apps
• Content Source: aspnetcore/blazor/integrate-components.md
• Product: aspnet-core
• Technology: aspnetcore-blazor
• GitHub Login: @guardrex
• Microsoft Alias: riande

[guardrex]

Hello @mrlife ... You're saying that it will work if you add an int prop to the component and assign to that (as the example shows) but as soon as you try a string prop it fails? Let's just rule out the possibility that this is a namespace problem. If it works for an int but not a string, then we'll go to engineering with this; but if they both don't work, then troubleshoot it as a namespace issue.

btw ...

unable to find the docs for the Component Tag Helper

You found 'um! 😄 ... We'll add to/modify these instructions as reports come in and indicate needed changes. If this turns out to be a namespace issue, then we can address that in this text.

[mrlife]

Hi @guardrex

You're saying that it will work if you add an int prop to the component and assign to that (as the example shows) but as soon as you try a string prop it fails?

Yes, that's what I'm seeing... The assignment of 10 like in the example works because it is numeric. If I add any characters, it throws the error.

If it works for a string but not an int then we'll go to engineering with this; but if they both don't work, then troubleshoot it as a namespace issue.

Never works for raw string but raw int works fine.

Also, would it be worthwhile to have a page in the docs that provides the details of the Component Tag Helper?

[guardrex]

In reverse order ...

Yes, I agree on that ... in the TH section of the TOC as a built-in TH. I can cross-link from here to there and place the additional content there on whatever this turns out to be.

WRT the error, open an issue with engineering ...

• https://github.com/dotnet/aspnetcore/issues
• Add a cc: @guardrex to the bottom of your issue so that I can track along.
• Leave this open. I'll work it when we get an answer over there, and I'll use this to track our visibility of the TH. Thanks for the suggestion @mrlife! 🎷

[mrlife]

Great thanks, here is the direct link to the issue: dotnet/aspnetcore#19466

[guardrex]

Note to self: Add the Blazor label for this topic to .ghal.rules.json when this issue is worked ...

"(?i).*master\/aspnetcore\/mvc\/views\/tag-helpers\/built-in\/component.md": {
  "labels-add": "Blazor"
},

[guardrex]

Now, we know! 💡 ... I'll update and work on a Component TH topic asap. It will be perhaps 1-2 weeks due to high priority Blazor issues.