The metadata_exists() function should return the correct value if the get_$meta_type_metadata filter returns a non null value

[xknown]

The line ​324 should return $check instead of true, otherwise the filter doesn't normally work when someone wants to always return false for a given meta key.

Here's a quick way to reproduce it

> add_filter('get_user_metadata', '__return_false'); return metadata_exists('user', 1, 1)
TRUE

[xknown]

Return $check instead of true.

[nacin]

This sounds OK to change. A simple unit test would be nice.

[xknown]

Updated patch. Cast to bool to match the metadata_exists() documentation.

[xknown]

Add two more assertions to the test_metadata_exists() test method.

[SergeyBiryukov]

Cast to bool to match the metadata_exists() documentation.

I think the documentation should be changed to @return mixed instead, which would be consistent with term_exists(): tags/3.8.1/src/wp-includes/taxonomy.php#L1561​.

[DrewAPicture]

Replying to SergeyBiryukov:

Cast to bool to match the metadata_exists() documentation.

I think the documentation should be changed to @return mixed instead, which would be consistent with term_exists(): tags/3.8.1/src/wp-includes/taxonomy.php#L1561​.

+1 for using mixed, as long as you spell out the various return types and conditions.

[nacin]

Replying to SergeyBiryukov:

Cast to bool to match the metadata_exists() documentation.

I think the documentation should be changed to @return mixed instead

This is for metadata_exists(), not get_metadata(). It either exists or doesn't.

[nacin]

In 27562:

Return false from metadata_exists() if the get_$type_metadata filter returns a false value.

props xknown.
fixes #22746.