search

dotnet / aspnetcore

ASP.NET Core is a cross-platform .NET framework for building modern cloud-based web applications on Windows, Mac, or Linux.
https://asp.net
MIT License
35.37k stars 9.99k forks source link

[Blazor] Attributes of HTML custom elements not yet initialized when connectedCallback() is invoked #6218

Closed ranabuelo closed 4 years ago

ranabuelo commented 5 years ago

Custom HTLM elements are usually initialized from the connectedCallback using the attributes from the DOM. Browsers therefore set all attributes at the custom element before the callback gets invoked.

In Blazor, however, element attributes are set after invoking the connectedCallback. This seems to happen in the BrowserRenderer.insertElement function where insertLogicalChild is called before the attributes are actually being applied. Moving the insertLogicalChild() call to the end of the function seems to solve the issue.

Occurred with Blazor 0.7.0.

mkArtakMSFT commented 5 years ago

Thanks for contacting us, @ranabuelo. This is not something we plan to do in the near future, yet we would happily consider a PR if you'd send one.

mkArtakMSFT commented 5 years ago

@ranabuelo could you also share details about what you are trying to do? How would you use such a feature?

ranabuelo commented 5 years ago

My use cases are straightforward:

When I used the same custom HTML element in a plain HTML/Javascript project, it worked fine. But it didn't work with Blazor because the connectedCallback was called before attributes have been set by Blazor, whereas in a static HTML context, browsers first set all attributes before invoking the connectedCallback. So right now I consider this to be a bug rather than a feature request...

I'll try to test with a recent preview version and provide a PR for it. Unfortunately, I don't get preview 3 running with VS 2019 because of issue #8384. So I probably need to wait for preview 4.

ma499 commented 5 years ago

Did you get a chance to try it out @ranabuelo?

Like you I’m interested in using Web Components within Blazor apps.

githubfanster commented 5 years ago

i am also interested in similar scenarios as discussed here by @ranabuelo. it would be nice to have blazor playing well with html custom elements

veikkoeeva commented 5 years ago

For the reference, some component libraries: https://open-wc.org/faq/component-libraries.html. From the referenced #10170, though this might be achieavable via JS interop -- looks like it -- a good experience with Web APIs and ability to author web components with Blazor would be nice.

Extending to the improbable, but to make this more complete, maybe also doing rendering like lit-html, hyperHTML and other string templating engines are doing (yes, there is RenderTree). Some more consideration to this in the linked #10170.

jspuij commented 4 years ago

@SteveSandersonMS Picking this one up for the Blazor July sprint.