Add "parent" parameter to get_term_by

[leogermani]

There has been some discussion around some inconsistencies in the way term_exists() handles the input string and sometimes can have unexpeceted results. The most recent discussions about this can be seen in #47099, #45333 and #32248.

The current recommendation is to use get_term_by() instead, so you can explicitly inform what field you are checking and get the right result.

However, get_term_by() does not support a parent argument, which makes it not a full term_exists() replacement.

In #47099 @boonebgorges suggested we opened an enhancement ticket to discuss this addition to this function. And here it is! :)

Looking at the function and all parameters it gets, we would have to decide how to support this.

This would be the first question to ask if one was to try an approach for this. Adding as a new parameter does not look so good because there already many and it would force the developer to use all of them if he/she wanted to use parent. However adding support for a field like name_and_parent or something like this, and having an array passed as the $value doesn't look so pretty either.

What do you think?

[SergeyBiryukov]

Replying to leogermani:

Looking at the function and all parameters it gets, we would have to decide how to support this.

This would be the first question to ask if one was to try an approach for this. Adding as a new parameter does not look so good because there already many and it would force the developer to use all of them if he/she wanted to use parent. However adding support for a field like name_and_parent or something like this, and having an array passed as the $value doesn't look so pretty either.

One option that comes to mind is to accept an array as the $field parameter, something like this:

get_term_by( array( 'field' => 'name', 'parent' => $parent_term_id ), 'Child term', $taxonomy )

At that point, though, it seems like we're just reinventing get_terms() with 'number' => 1:

get_terms( array( 'name' => 'Child term', 'parent' => $parent_term_id, 'taxonomy' => $taxonomy, 'number' => 1 )

[leogermani]

Replying to SergeyBiryukov:

One option that comes to mind is to accept an array as the $field parameter, something like this:

get_term_by( array( 'field' => 'name', 'parent' => $parent_term_id ), 'Child term', $taxonomy )

At that point, though, it seems like we're just reinventing get_terms() with 'number' => 1:

get_terms( array( 'name' => 'Child term', 'parent' => $parent_term_id, 'taxonomy' => $taxonomy, 'number' => 1 )

Thanks for the reply!

get_term_by already uses get_terms internally... so it is basically a shortcut to get_terms with some fixed parameters indeed. So you have a point, if we add too many options to it, it misses the point of being a shortcut.

I have been using get_terms as a replacement for term_exists and it works well.

I think we have to ask:

• should we deprecate term_exists()? I understand it's not desirable to change its behavior because it could break things

I think that yes, we should deprecate it (if fixing it by adding a 'field' parameter isn't really an option). We have a function that is not reliable.

If we deprecate it, we should recommend the new way of doing so, which could be

• recommending get_terms,
• adding parent option to get_term_by or
• creating a new function.

I particularly think that this is something very useful and would be nice to have something specific rather than having to use get_terms.