Don't add empty "_wp_attachment_metadata" on non-image media files

[Caspie]

I'm currently working on a community project where there are a lot of front-end file uploads. I've noticed that when you upload a non-image file, an empty _wp_attachment_metadata is added to the postmeta table. Just did a quick patch to check the $data in wp_update_attachment_metadata function. And since $data comes always as an array from wp_generate_attachment_metadata, we do not update if it is an empty array.

[scribu]

You should use !empty() instead of count().

[Caspie]

empty() is faster :)

[Caspie]

Replying to scribu:

You should use !empty() instead of count().

thx! for better performance I guess?

[scribu]

Yep.

[nacin]

We can actually just say if ( $data ).

[nacin]

When updating an attachment with empty file or data after it previously had a meta value for _wp_attached_file or _wp_attachment_metadata, the data would not get cleared.

The options are either not applying this patch, or doing if ( $date ) update; else delete;

I no longer consider this a pure bug.

[wonderboymusic]

I like the latest Sergey approach

[scribu]

Why do we have to do this in 3 places?

[wonderboymusic]

different metadata being altered

[ryan]

In [21967]:

Don't add empty _wp_attached_file, _wp_attachment_metadata, _thumbnail_id meta to posts. Delete these fields when set to empty. Props SergeyBiryukov, Caspie. fixes #16391