WordPress at a glance
filter is not described

rest_pre_insert_(post_type) filter-hook . WP 4.7.0

Filters a post before it is inserted via the REST API.

The dynamic portion of the hook name, $this->post_type, refers to the post type slug.

Usage

add_filter( 'rest_pre_insert_(post_type)', 'filter_function_name_2088', 10, 2 );
function filter_function_name_2088( $prepared_post, $request ){
	// filter...

	return $prepared_post;
}
$prepared_post(stdClass)
An object representing a single post prepared for inserting or updating the database.
$request(WP_REST_Request)
Request object.

Where the hook is called

WP_REST_Posts_Controller::prepare_item_for_database()
wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php 1112
return apply_filters( "rest_pre_insert_{$this->post_type}", $prepared_post, $request );

Where the hook is used (in WP core)

Does not used.