Create taxonomy with meta term using the WP Rest Api

I am trying to create taxonomy elements (the taxonomies are already registered) from the front end using the REST Api v2. I am able to do so except not able to save the meta fields from the taxonomies.

I have a registered taxonomy (“place”) and I am trying to create elements for it using the Rest Api.

The taxonomy has a term meta (“my_meta”). I am able to get the information from the taxonomy:

add_action( 'rest_api_init', 'slug_register_meta' );
function slug_register_meta() {
    register_rest_field( 'place',
        'meta', 
        array(
            'get_callback'    => 'slug_get_meta',
            'update_callback' => null,
            'schema'          => null,
        )
    );
}
function slug_get_meta( $object, $field_name, $request ) {
    return get_term_meta( $object[ 'id' ] );
}

which lets me get the information when I access: /wp-json/wp/v2/place/53

{
    "id": 53,
    "count": 0,
    ...
    "taxonomy": "place",
    "meta": {
        "my_meta": [
            "the meta value"
        ]
    },
    ...
}

I can register a new taxonomy element through JavaScript:

var place_new = new wp.api.models.Place({
    name: 'the name',// works
    description: 'the description',// works

    my_meta: 'test1',// doesn't work

    fields: {// doesn't work
        my_meta: 'test3'
    },

    meta: {// doesn't work
        my_meta: 'test2'
    }

    });

place_new.save();

The problem is the my_meta value won’t save, I am not sure how to refer to it or if there is some PHP I am missing.

I think you need an update_callback in register_rest_field(). Please note that I haven’t tested this.

add_action( 'rest_api_init', 'slug_register_meta' );
function slug_register_meta() {
    register_rest_field( 'place',
        'meta', 
        array(
            'get_callback'    => 'slug_get_meta',
            'update_callback' => 'slug_update_meta',
            'schema'          => null,
        )
    );
}
function slug_get_meta( $object, $field_name, $request ) {
    return get_term_meta( $object[ 'id' ] );
}
function slug_update_meta($value, $object, $field_name){
    // please note: make sure that $object is indeed and object or array
    return update_post_meta($object['id'], $field_name, $value);
}