Using pre_get_posts, how to target the REST API, only?

Question

The title says it all: Is it possible to set a condition in pre_get_posts that only applies to queries that are targeted at the REST API?

Bysander · Accepted Answer · 2022-03-31 15:14:25Z

2

Yes.

So long as the code you're running happens after parse_request - which pre_get_posts does. (See https://codex.wordpress.org/Plugin_API/Action_Reference#Actions_Run_During_a_Typical_Request)

Then you will have a nice constant to use: REST_REQUEST

Something like

if( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
    // ...do RESTy things
}

will do the trick.

answered Mar 31, 2022 at 13:45

Bysander

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Thanks. Seems to work like a charm.
– MastaBaba
Mar 31, 2022 at 14:30
Actually, this doesn't seem to quite always work as expected: To avoid targeting all queries, you can use $query->is_main_query(), but this doesn't seem to work in combination with this if-then.
– MastaBaba
May 16, 2022 at 23:27

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