MongoDBRef::isRef Checks if an array is a database reference &reftitle.description; public static boolMongoDBRef::isRef mixedref This not actually follow the reference, so it does not determine if it is broken or not. It merely checks that ref is in valid database reference format (in that it is an object or array with $ref and $id fields). &reftitle.parameters; ref Array or object to check. &reftitle.returnvalues; Returns if ref is a reference.