validate postId in the site-editor.php

[mi5t4n]

Added validation for the postId parameter in site-editor.php to ensure that the post exists before proceeding. If the post ID is invalid or the post does not exist, the script will now terminate with an error message, preventing potential errors or unintended behavior.

Trac ticket: https://core.trac.wordpress.org/ticket/61796

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Props mi5t4n, hellofromtonya, peterwilsoncc, davidbaumwald, benniledl.

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[peterwilsoncc]

I've added a couple of notes inline.

While testing I noticed that going to wp-admin/site-editor.php?postType=page&canvas=edit ignores the postType parameter and loads the Blog Home template.

It suggests that further validation of the user input via the URL is required

[peterwilsoncc]

CS: Remove double line break.

Edit: You'll need to do this manually as the inline suggestion doesn't appear to like white space changes.

[dream-encode]

Though it's probably beyond the scope of the original ticket, I see a lot of duplication of isset( $_GET['postType'] ) and sanitize_key( $_GET['postType'] ).

Wondering if we could have something like a default $current_post_type = false|null then check and sanitize it once for reuse in the rest of the file. Same could pro be done for $_GET['postId'] and $_GET['path']?

Could probably move the early bails a bit higher in the file as well, to save some unnecessary code running when it's not needed? Just based off a brief look, unless I am missing something, I don't see anything between lines 76 and 118 that is in any way dependent on any of the code running above.

[benniledl]

would be nice to have an error message for various post statuses as in #7215

[mi5t4n]

@dream-encode @peterwilsoncc Thank you for the suggestions. I have made the changes.

[peterwilsoncc]

I've added a few notes inline for additional reuse of $post_type_param and to avoid a potential PHP error if the value is not set.

[hellofromtonya]

Before 6.6.0, it redirected to site-editor.php?path=%2Fpage&canvas=view. Granted that did not indicate the why.

Why wp_die()?

My concern is two-fold:

• Before this bug: It redirected, but stayed in the Site Editor.
• Will the user understand how to get back to the editor, i.e. get out of this error page?

I'm wondering:

Could a lighter approach might be a better user experience? "lighter" meaning -> retain the previous behavior to keep the user in the Site Editor, while also displaying a message to inform the user why their requested page did not show.

@dream-encode @peterwilsoncc What do you think?