Fix: Return result from wp_register_block_template function

[AnmolVerma404]

What?

• While reviewing PR Rename wp_register_block_template() to register_block_template() #65958 , I noticed that the deprecated function wp_register_block_template does not return a result. This seems to have been overlooked.

Why?

• The function wp_register_block_template is deprecated, and the legacy code that makes use of the return result might break, as no result is being returned. That's why it is necessary to return the result here.

How?

• It simply returns the results from the newly renamed function register_block_template.

Testing Instructions

[Reffering example from #65958 PR]

1. Add this code to an existing plugin or in a code snippet using the Code Snippets plugin:. If you use wp_register_block_template and utilize the return result, it will work as expected.

add_action(
	'init',
	function () {
		$template = wp_register_block_template(
			'gutenberg//plugin-template',
			array(
				'title'       => 'Plugin Template',
				'description' => 'A template registered by a plugin.',
				'content'     => '<!-- wp:template-part {"slug":"header","tagName":"header"} /--><!-- wp:group {"tagName":"main","layout":{"inherit":true}} --><main class="wp-block-group"><!-- wp:paragraph --><p>This is a plugin-registered template.</p><!-- /wp:paragraph --></main><!-- /wp:group -->',
			)
		);
		print_r( $template );
		add_action(
			'category_template_hierarchy',
			function () {
				return array( 'plugin-template' );
			}
		);
	}
);

2. The print_r( $template ) statement should be visible on any page of the site. It should return a WP_Block_Template or WP_Error object.

if ( $template instanceof WP_Error ) {
    // Handle WP_Error object
}

if ( $template instanceof WP_Block_Template ) {
    // Handle WP_Block_Template object
} 

3. Go to a post category in the frontend (ie: /category/test-category/) and verify the Plugin Template contents are rendered.
4. Go to Appearance > Editor > Templates and verify the Plugin Template appears with the correct title and description.
5. Make some edits to the template. Verify they are applied in the frontend.
6. Revert the edits and verify edits are reverted in the frontend as well.
7. Edit the previous code snippet adding these lines:

		unregister_block_template( 'gutenberg//plugin-template' );

8. Verify the template no longer appears under Appearance > Editor > Templates and going to a post category in the frontend doesn't render it either.

[github-actions]

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Co-authored-by: AnmolVerma404 <anmolverma404@git.wordpress.org>
Co-authored-by: Aljullu <aljullu@git.wordpress.org>
Co-authored-by: kevin940726 <kevin940726@git.wordpress.org>

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[github-actions]

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[Aljullu]

Thanks for fixing this, @AnmolVerma404! Code changes looks good and it's testing well. I would only make a change to the testing step code snippet to something like this:

add_action(
	'init',
	function () {
		$template = wp_register_block_template(
			'gutenberg//plugin-template',
			array(
				'title'       => 'Plugin Template',
				'description' => 'A template registered by a plugin.',
				'content'     => '<!-- wp:template-part {"slug":"header","tagName":"header"} /--><!-- wp:group {"tagName":"main","layout":{"inherit":true}} --><main class="wp-block-group"><!-- wp:paragraph --><p>This is a plugin-registered template.</p><!-- /wp:paragraph --></main><!-- /wp:group -->',
			)
		);
		print_r( $template );
		add_action(
			'category_template_hierarchy',
			function () {
				return array( 'plugin-template' );
			}
		);
	}
);

And then add a step to verify the template object is correctly printed on the screen.

Besides that, LGTM. 🙂

[AnmolVerma404]

@Aljullu , I've added the changes to the testing code snippet in the PR description ✅

[Aljullu]

Thanks for updating the testing steps, @AnmolVerma404!

@kevin940726 I see you added the "Backport to WP 6.7" label, but this specific code only exists in Gutenberg, not in WP core, so my understanding is that no porting is needed, right? Please let me know if I'm missing something.

[kevin940726]

Hmm yeah! Sorry for holding this. Any idea why the original PR was backported though? I'll remove the label for now to unblock this.

[Aljullu]

No worries, @kevin940726! The original PR was renaming a couple of functions to remove the wp_ prefix. In Gutenberg we kept the old functions as deprecated while in WordPress core we simply renamed the functions (it was decided here: #61577 (comment)).

Given that this PR only modifies the deprecated functions, it only needs to be in Gutenberg and can't be ported to WP core.

Hope it makes sense! I will go ahead and merge it for now.

[ntsekouras]

Looks good, thanks!