The REST API in WordPress 5.3

WordPress 5.3 contains a number of REST API improvements designed to make it easier and faster to work with API data from the block editor or other client applications.

Register Array & Object Metadata

As covered previously in this developer note on array & object metadata, it is now possible to use register_post_meta & register_term_meta (as well as the underlying method register_meta) to interact with complex meta values as schema-validated JSON arrays or objects using the REST API. See the linked post for more details.

Nested response filtering with _fields query parameter

This developer note on the changes to the REST API’s _fields= query parameter shows how you may now filter your REST API response objects to include only specific nested properties within the response body.

Ticket #42094

Set drafts back to “floating date” status

Once a date has been set for a draft, it was previously impossible to set the post back to showing “publish immediately” (also referred to as a “floating date,” where the post will be dated whenever it is published). As of 5.3, passing null for a date value will unset the draft date and restore this floating state.

Ticket #39953

Faster Responses

We have introduced a caching wrapper around the generation of REST resource schema objects, which initial testing has shown to yield up to a 30-40% performance increase in large API responses. If you work with expensive or large REST API queries, things should be quite a bit faster now. (Ticket #47871)

The REST API has also been improved to avoid unnecessary controller object instantiation (#45677) and to skip generation of sample permalinks when that data is not requested (#45605).

Please Note: if your team has existing performance benchmarking tooling for the REST API, please contact the component maintainers in the #core-restapi Slack channel; we very much desire to expand our metrics in this area.

Additional Changes of Note

In addition to these key enhancements, there are a number of smaller improvements to the REST API which may be of interest to developers.

  • It is no longer possible to DELETE a Revision resource using the REST API, as this behavior could break a post’s audit trail. Ticket #43709
  • The /search endpoint will now correctly embed the full original body of each matched resource when passing the _embed query parameter. Ticket #47684
  • rest_do_request and rest_ensure_request now accept a string API path, so it is possible to instantiate a request in PHP using nothing more than the desired endpoint string, e.g.
    rest_do_request( '/wp/v2/posts' );
    Ticket #40614
  • Creating or updating a Terms resource via the REST API now returns the updated object using the “edit” context. Ticket #41411
  • It is now possible to edit a posted comment through the REST API when authenticating the request as a user with the moderate_comments capability. Previously a full editor- or admin-level role was needed. Ticket #47024
  • rest_get_avatar_urls now receives the entire User or Comment object, not just the object’s email address. Ticket #40030

Welcoming Timothy Jacobs as a REST API component maintainer

Last but not least, many of you have no doubt seen @timothyblynjacobs active in trac, slack, and community events. Timothy has driven much of the momentum that resulted in the above improvements, and I’m excited to (belatedly) announce that he has joined the REST API team as an official component maintainer. Thank you very much for your energy and dedication!

Thank you also to every other person who contributed to API changes this cycle; it’s the best version of the REST API yet, and we couldn’t have done it without the dozens of contributors who helped create, review and land these patches.

We’ve got some ambitious ideas about how we can make the REST API even better in 5.4. Interested in helping out, with code, docs, or triage? Join us for weekly office hours, every week on Thursdays at 1800 UTC!

#5-3, #dev-notes, #rest-api