Allow WordPress REST API to read a single post, by post status

modify_rest_caps.php

	add_filter( 'user_has_cap', array( __CLASS__, 'allow_rest_to_read_single_archived_module' ), 10, 3 );

	/***
	 * Modify the capabilities of the REST API to view a single
	 * "module" post if requested with its post ID.
	 *
	 * @param $allcaps
	 * @param $cap
	 * @param $args
	 *
	 * @return mixed An array of granted capabilities
	 */
	static function allow_rest_to_read_single_archived_module($allcaps, $cap, $args) {

		/* Bail if this isn't a rest call */
		if (strpos($_SERVER['REQUEST_URI'], '/wp-json/wp/v2/') === false) return $allcaps;

		/* Get the current post */
		$post = get_post( $args[2] );

		/* If CPT isn't "module", get out */
		if ($post->post_type !== 'module') return $allcaps;

		/* Add the capability to read the post details */
		$allcaps["read_posts"] = true;

		/* Return the capabilities */
		return $allcaps;
	}