Customizing WordPress API data

1// add_filter parameter
2add_filter( string $tag, callable $function_to_add, int $priority = 10, int $accepted_args = 1 )

 1// Add Featured Image source URLs to the `/posts/` endpoint response
 2
 3function add_featured_image_url ($data, $post, $context) {
 4	$featured_image_id = $data -> data['featured_media']; // get featured image ID from $data
 5	$featured_image_url = wp_get_attachment_image_src( $featured_image_id, 'original' ); // get URL of original size
 6	$featured_image_url_thumbnail = image_get_intermediate_size( $featured_image_id, 'thumbnail' ); // get URL of thumbnail size
 7	$featured_image_url_medium = image_get_intermediate_size( $featured_image_id, 'medium' ); // get URL of medium size
 8
 9	if ( $featured_image_url_thumbnail ) {
10		$data -> data['featured_image_url']['thumbnail'] = $featured_image_url_thumbnail['url'];
11	}
12
13	if ( $featured_image_url_medium ) {
14		$data -> data['featured_image_url']['medium'] = $featured_image_url_medium['url'];
15	}
16
17	if ( $featured_image_url ) {
18		$data -> data['featured_image_url']['full'] = $featured_image_url[0];
19	}
20
21	return $data;
22}
23
24add_filter( 'rest_prepare_post', 'add_featured_image_url', 10, 3); // 10 is priority and 3 is accepted_args. Both are optional

1featured_image_url: {
2	thumbnail: "https://news.mydomain.net/wp-content/uploads/images/myimage-150x150.jpg",
3	medium: "https://news.mydomain.net/wp-content/uploads/images/myimage-300x200.jpg",
4	full: "https://news.mydomain.net/wp-content/uploads/images/myimage.jpg"
5},

 1// Add comment count to the API response
 2function add_comment_count($data, $post, $context) {
 3	$args = array(
 4		'post_id' => $post -> ID, // Limit results affiliated with this post ID. Default 0.
 5		'count' => true, // return only the count, not an array of comment objects
 6		'status' => 'approve'
 7	);
 8	$comments = get_comments( $args );
 9
10	$data -> data['comment_count'] = $comments;
11
12	return $data;
13}
14
15add_filter( 'rest_prepare_post', 'add_comment_count', 10, 3);

 1ID: 3347,
 2post_author: "1",
 3post_date: "2019-05-24 15:29:47",
 4post_date_gmt: "2019-05-24 15:29:47",
 5post_content: "This is post content. Blah blah blah",
 6post_excerpt: "This is the post excerpt. More blah.. ",
 7post_status: "publish",
 8comment_status: "open",
 9ping_status: "closed",
10post_password: "",
11post_name: "this-be-the-post-slug",
12to_ping: "",
13pinged: "",
14post_modified: "2019-06-18 07:21:50",
15post_modified_gmt: "2019-06-18 07:21:50",
16post_content_filtered: "",
17post_parent: 0,
18guid: "https://news.mydomain.net/p=?3347",
19menu_order: 0,
20post_type: "post",
21post_mime_type: "",
22comment_count: "8",
23filter: "raw"

 1// Custom Excerpt
 2// Remove the continue reading link from auto generated excerpts by defining our own custom excerpt if one hasn't been added by user
 3function custom_excerpt ($data, $post, $context) {
 4
 5	// unset( $data -> data['excerpt'] ); // remove the excerpt field (if you want to overwrite the default 'excerpt' response sent by the API)
 6
 7	$content = $post -> post_content;
 8	$more = ' ... ';
 9
10	if ( ! has_excerpt($post -> ID)) {
11		// This post does not has a user defined excerpt
12		$data -> data['excerpt']['raw'] = wp_trim_words( $content, 55 , $more );
13	}
14	return $data;
15}
16
17add_filter( 'rest_prepare_post', 'custom_excerpt', 10, 3);

1function whothis ($data, $post, $context) {
2	$whothis = $post;
3	$data -> data['whothis'] = $whothis;
4	return $data;
5}
6add_filter( 'rest_prepare_post', 'whothis', 10, 3);