Add a guide for "how to work with meta"

[nezzard]

Hi, i tried to update post meta, when i created posts, but nothing happened
It's possible with node-wpapi?
wp.song().create({ title: '1', content: 'Your post content', status: 'publish', meta: {key: 'youtube', value: '12'}, }).then(function( response ) { console.log( response.id ); })

[bigandy]

On the WordPress side of things you'll need to set things up so that you can read and post meta. See http://v2.wp-api.org/extending/modifying/#read-and-write-a-post-meta-field-in-post-responses

[kadamwhite]

A better option these days is to use first-party meta support, introduced in 4.6, detailed here in this API status update post and further explained in the README from the pull request for meta handling

[chattes]

@kadamwhite is there some change I have a meta field upvote for my custom post and I have registered using register_meta() , as suggested and when I use a get request , I am getting the meta values like..

  "meta": {
    "upvote": "4",
    "downvote": "0"
  }

When I try to update it works via postman if I pass the body as

{ "meta": {
    "upvote": "5"
} }

But the node-wpapi does not take this, if I pass it as

{
meta:{
key:'upvote'
value: '4'
}}

It does not update the values.

[kadamwhite]

Merging #286 into this issue; documenting how to work with custom meta is currently our top-priority docs issue

[dimadin]

When you create/update post, you pass meta object, for example:

wpapi.posts().create( {
	title: 'Your Title',
	content: ' Your content',
	status: 'publish',
	meta: {
		custom_meta_key: 'something'
	}
} ).then( function( response ) {
	// whatever
} );

On the server side, you must use register_meta(). If you are using custom post type, the post type must have custom-fields support (see documentation for $args['supports'] of register_post_type(). That is documented for REST API.

But if you are using meta with custom role, your role should also have edit_post_meta (and delete_post_meta if you are deleting) capability. See code for WP_REST_Meta_Fields::update_meta_value() and WP_REST_Meta_Fields::delete_meta_value(). I haven't seen that this is documented anywhere so I figured it out during debugging.

[sculpt0r]

@dimadin Sorry, but could You be more specific, where exactly on server side I should change something to get meta work?

[dmdb]

Messed with the same problem, being total noob in wordpress infrastructure. Solved by putting

register_meta('post', 'duration', [
  'type' => 'integer',
  'description' => 'duration',
  'single' => true,
  'show_in_rest' => true,
]);

into functions.php of theme. This unlocked me:

meta: { duration: 123 }

[kadamwhite]

@calemb @dmdb In WordPress 5.0 note that this will change to register_post_meta( 'post', ... -- the snippet you have here will register "duration" for all custom post types. (You'd change 'post' to 'my_cpt' if you want duration to apply to a custom post type). We will be releasing a comprehensive update to our meta handling documentation on the REST API handbook in conjunction with 5.0.

[b02902032]

I've been struggling for a few days and finally found how to deal with it.
I added two meta fields to comment meta, which are "likes" and "pin".
To enable POST request from frontend like reactjs, I need to add "likes" and "pin" to REST API.
This is how I add and update data:
Since I am very new to Wordpress and PHP, I spent most of the time finding out why comment meta is not updating through update_comment_meta. It turns out that I need to access the comment id through $comment_object->comment_ID not $comment_object->ID. So, make sure you are familiar with the type you are working on.

function slug_register_comment_meta() {
    register_rest_field( 'comment',
        'likes',
        array(
            'get_callback'    => 'slug_get_comment_meta',
            'update_callback' => 'slug_update_comment_meta',
            'schema'          => array('likes' => 'The number of likes received in this comment.'),
        )
    );
    register_rest_field( 'comment',
        'pin',
        array(
            'get_callback'    => 'slug_get_comment_meta',
            'update_callback' => 'slug_update_comment_meta',
            'schema'          => array('pin' => 'If this comment is pinned or not.'),
        )
    );
}

function slug_get_comment_meta( $comment_object, $field_name, $request ) {
  return get_comment_meta( $comment_object['id'], $field_name , true );
}

function slug_update_comment_meta( $value, $comment_object, $field_name ) {
  return update_comment_meta( $comment_object->comment_ID, $field_name, wp_slash( $value ) );
}
add_action( 'rest_api_init', 'slug_register_comment_meta' );

I only test the code with curl in my terminal:

curl -X POST http://website.com/wp-json/wp/v2/comments -H 'content-type: application/json' -d '{"post": 1, "content":"comment meta test", "author_name":"name", "author_email":"email@gmail.com", "likes":"1000", "pin":"1"}'