Respect forms with enctype set for view transitions

[knpwrs]

Changes

This makes progressively-enhanced forms (via ViewTransitions) respect the enctype attribute.

Closes #9447.

Testing

I built the repo and added a form to the view transitions example and tried submitting the form with both enctype set and not set.

Docs

I will submit a PR to update the docs.

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[martrapp]

Hi @knpwrs, thanks for your quick PR!

While it solves the original problem and maintains compatibility for the encoding behavior, it still leads to incompatibilities in the client-side router and transition events.

Could you please try to base your solution on the existing sourceElement property? I have left details in the comments in the code. That way you could access the form directly or via the event's handler from the defaultLoader(). If this works, no changes to the navigate() options or the events would be required.

[knpwrs]

@martrapp thank you for the feedback, I think these changes should address what you've said.

[martrapp]

Great! Much more concise! Were you able to test it? Does it sill work?
I guess, sourceElement is not always the <form> element but might also be a "submitter" <button> or similar. In that case we first need to identify the form.

[knpwrs]

The latest commit is tested and working with both forms and submitters.

[martrapp]

So far everything looks good and it was very pleasant and productive how you solved the problem! I'm very happy with where we are now. As you wrote, we can simply fall back to the standard of form.enctype for 5.0. I like to quote a dear colleague: definitely much "better than what we had before".

I don't want to overshoot the mark, but we need additional e2e tests now. Since we don't have a long history together yet, I'll ask very carefully: do you want to add them or are you satisfied with what we've achieved so far ;-)

[knpwrs]

I'm open to giving it a go tonight. It'll be a good opportunity to try out playwright test and I can see there's some prior-art for view transitions that I can model after.

[martrapp]

😃 Thanks a lot! As you may have seen, all e2e tests for view transitions are located in packages/astro/e2e/view-transitions.test.js. The server-side for the current tests under packages/astro/e2e/fixtures/view-transitions/src/pages/form-* is defined in packages/astro/e2e/fixtures/view-transitions/src/pages/contact.ts. As you can see, we don't usually have full coverage, but enough to recognize when something isn't working. Maybe you can test that application/x-www-form-urlencoded makes it to the server-side for a form and submitter case, and test that multipart/form-data is used when enctype is not set. Get back to me if I can/should lend you a hand!

[natemoo-re]

Works for me! Would be great to have tests, as @martrapp suggested!

[knpwrs]

Tests have been pushed!

[martrapp]

Very good solution! Thank you again, it was a pleasure!