_prepare_post example

$post = get_post( $post_id, ARRAY_A );

        if ( empty( $post['ID'] ) ) {
            return new IXR_Error( 404, __( 'Invalid post ID.' ) );
        }

        if ( ! current_user_can( 'edit_post', $post_id ) ) {
            return new IXR_Error( 401, __( 'Sorry, you are not allowed to edit this post.' ) );
        }

        return $this->_prepare_post( $post, $fields );
    }

    /** * Retrieves posts. * * @since 3.4.0 * * @see wp_get_recent_posts() * @see wp_getPost() for more on `$fields` * @see get_posts() for more on `$filter` values * * @param array $args { * Method arguments. Note: arguments must be ordered as documented. * * @type int $0 Blog ID (unused). * @type string $1 Username. * @type string $2 Password. * @type array $3 Optional. Modifies the query used to retrieve posts. Accepts 'post_type', * 'post_status', 'number', 'offset', 'orderby', 's', and 'order'. * Default empty array. * @type array $4 Optional. The subset of post type fields to return in the response array. * } * @return array|IXR_Error Array containing a collection of posts. */