update_metadata() updates unchanged values

[ryan]

update_metadata() generates an UPDATE query even if the value is the same as in the DB. When saving nav menus, for example, this results in many pointless updates.

[ryan]

(In [14564]) Don't update meta data when the new value matches the old value. fixes #13350

[jayarjo]

Stumbled upon a defect, which brought me to exactly this piece of code (my plugin stopped working after upgrade to WP 3.0 RC2 from 2.9.2). I store multi-dimensional hybrid array (associative array with some values being indexed arrays) as a post meta, and for some reason == operator fails to check equality of prev and new values (no idea why, I haven't heard of such either, quick googling haven't brought any results, but it fails for sure).

The quick fix for this would probably be doing serialize first followed by equality check.

[jayarjo]

Damn, sorry for lame bug report. Tried to be helpful :D Actually old_value would need serialize as well to actually check for equality and not for nothing.

[shawnparker]

I just ran in to this as well and the issue for me is that a == check on two arrays will check that all the key/value pairs match, but doesn't care about order. This should probably be a === check to make sure that comparisons are strict.

Will attach patch in a second.

[shawnparker]

Patch to perform strict === check of old and new metadata instead of loose == check

[shawnparker]

Sorry to be chatty, but I just thought about the strict check and its possibility to damage any data that is loosely delivered to update_postmeta. integer 1 passed in to the function vs. string 1 pulled from the text field in the database could cause issues... maybe some kind of md5 hash check is more in order here?

[ryan]

(In [15390]) Perform strict equality comparison. Props shawnparker. fixes #13350 for 3.0.1

[ryan]

[15389] for trunk.