wp_send_json_error() should support WP_Error objects

[danielbachhuber]

It would be nice if I could just pass my WP_Error object directly to wp_send_json_error()

Related #28523

[nacin]

I like this. I think it should result in 'code', 'message', and 'data' keys. We already use 'message' keys in a few places for wp_send_json_error().

However, WP_Error can have more than one code/message pair. At that point, what should happen?

1. Should it be only the first code?
2. Should it put the first code/message pair in their own keys, then all others in an 'additional'-keyed array of code/message pairs?
3. Should it put the first code/message pair in their own keys, then all of them (including that one) in a 'all' keyed array of all code/message pairs?
4. Should it be an array of code/message pairs?

The problem with the fourth one is it would result in a different way of fetching a code/message for a single WP_Error versus a multiple WP_Error. Unless we make it so a WP_Error is always an array (so you'd always have to ask for the 0'th value), which seems annoying.

Based on the fact that WP_Error get_error_code() does return the first code (same for message, etc.), and then there's a separate get_error_codes() etc., I'd think that point 3 makes the most sense.

[rmccue]

+1. The way we're doing it with the ​REST API might be relevant too; basically we return an array of objects with both code and message properties.

[paulschreiber]

In the attached patch, I tried to emulate what @rmmcue did.

wp_send_json_error() calls is_wp_error() on the parameter it was passed. If true, it iterates over the object and sets $result['data'] to the just-created array.

[nacin]

Looks like those array casts can be dropped without an issue. (Yes, WP_Error also has a seemingly unnecessary array cast inside it.)

[paulschreiber]

Attached patch without casts.

[nacin]

This looks good to me. Anyone else?

Not sure if intentional, but I think I agree with omitting error data. Codes and messages are simple strings, while error data can be basically anything and that may not translate well to JSON. In core, the data is a another WP_Error in some cases (like in updates).

We can always add error data later as it'd be just another key in the object. Just thinking about forwards compatibility.

[rmccue]

Any chance we can move the WP_Error stuff out to a separate function? That way we can use it in the REST API easily (wp_send_json_error itself is a no-go, as it isn't re-entrant).

(Also, we could consider adding a filter there in case someone does want to add the data back for debugging or similar.)

[johnbillion]

In 30506:

Add support for WP_Error objects passed to wp_send_json_error(). The error object gets output as an array of error codes and messages, rather than as an empty object.

Fixes #28978
Props paulschreiber