New filter hook for get_metadata()

[JD55]

The get_metadata() function has one filter hook: get_{$meta_type}_metadata. While this filter can be used to override or short-circuit the return of get_metadata(), it can't easily be used to filter the meta value. In the options API, get_option() has two hooks: pre_option_$option and option_$option. The get_{$meta_type}_metadata corresponds to the former, but it would be useful to have something similar to option_$option that will filter the actual meta value. Maybe get_{$meta_type}_metadata-{$meta_key}?

[JD55]

Added patch with filter get_{$meta_type}_metadata-{$meta_key}.

[sc0ttkclark]

As the lead developer of the Pods project, I would also find this useful so we could only cover the fields that the user creates, instead of loading up the Pod config and checking if the field exists for that meta_key.

[MikeHansenMe]

Refresh and cleanup

[MikeHansenMe]

Added Docs and Refresh

[jtsternberg]

Hmm, wouldn't it be preferable to put the new filter up above/below the existing "get_{$meta_type}_metadata" filter? [Like this](​https://github.com/WebDevStudios/CMB2/blob/master/includes/CMB2_Field.php#L191-L227).

[sc0ttkclark]

+1 on specificity before catch-all filter (meta key filter first)

[MikeHansenMe]

I think one difference is that it is passing the meta_value into the filter which is not set until later in the function.

[jtsternberg]

Ah, my fault, the purpose of the ticket is to provide a filter on the retrieved value, but I think it also makes sense to have a pre_get filter above the catchall.

[jtsternberg]

Add new filter

[jtsternberg]

Updated patch which includes another pre-get filter with the meta-key as a dynamic portion of the hook name (and only if they passed a meta-key), and changed the actual value filter name to "{$meta_type}_metadata_value" since its actual purpose is to filter the value. I also removed the dynamic meta-key from the hook (and instead passed it as a parameter) at that point since we are not guaranteed to have one.

[MikeHansenMe]

@jtsternberg, couldn't you just hook on get_{$meta_type}_metadata and check the meta_key that is passed in? Seems to accomplish the same without the additional filter.

[jtsternberg]

I think @sc0ttkclark may weigh in as well, but there are many reasons why that would be valuable. Also, it follows precedence with the "pre_option_{$option}" filter: ​https://github.com/WordPress/WordPress/blob/master/wp-includes/option.php#L45

[MikeHansenMe]

yea, thought about the similar implementations after I posted. Makes sense.

[jeremyfelt]

#36088 was marked as a duplicate.

[MikeHansenMe]

@jtsternberg's patch 24726.4.diff​ still applies.