setEndpoint('https://.cloud.appwrite.io/v1') // Your API Endpoint ->setProject('') // Your project ID ->setKey(''); // Your secret API key $databases = new Databases($client); $result = $databases->createRelationshipAttribute( databaseId: '', collectionId: '', relatedCollectionId: '', type: RelationshipType::ONETOONE(), twoWay: false, // optional key: '', // optional twoWayKey: '', // optional onDelete: RelationMutate::CASCADE() // optional );