Template contents are wiped out on rename

[alshakero]

If you have a custom filter hooked to the hooked_block_types, renaming a wp_template will wipe its contents.

This stems from the callback inject_ignored_hooked_blocks_metadata_attributes checking has_filter( 'hooked_block_types' ) and filtering the template content when this call returns true. You can see the code ​here.

This is fine, but it assumes that the changes request will always have the post content, which is not true in the case of renaming. This assumption results in ​this code running, even when there are no changes to the post content, which sets the post_content to an empty string, overwriting the original content.

To reproduce:

1. Add an mu-plugin containing the following code: function somehook() {}; add_filter( 'hooked_block_types', 'somehook' , 10, 4 );.
2. Rename a custom template.
3. Its content will be wiped out.

Patch: ​https://github.com/WordPress/WordPress/pull/710

The ticket explains the problem.

Trac ticket: https://core.trac.wordpress.org/ticket/61550

[alshakero]

You can see a detailed bug report of this bug with a nice video ​here.

[hellofromTonya]

This stems from the callback inject_ignored_hooked_blocks_metadata_attributes checking has_filter( 'hooked_block_types' ) and filtering the template content when this call returns true. You can see the code ​here.

This ticket identifies [58614] / #60854 as the possible change introducing the issue. Pinging @bernhard-reiter for awareness.