Information Technology Tips

FirestoreでAuto Increment Fieldを作成 Firestoreで連番となるフィールドの作成方法を紹介します。 肝はFirestoreのtransactionを使って原子性(Atomicity)、一貫性(Consistency)、独立性(Isolation)を保証することです。 汎用的に使えるgenerateSequenceNumber関数を作成してみました。 manage_collection: 連番を生成するターゲットcollectionを管理するcollection名 target_collection: 連番を生成するターゲットとなるcollection名 numberField: 連番を生成したいフィールド名 を渡して使います。 function generateSequenceNumber ( db , manage_collection , target_collection , numberField ) { const docRef = db . collection ( manage_collection ) . doc ( target_collection ) ; return db . runTransaction ( ( transaction ) => { return transaction . get ( docRef ) . then ( ( doc ) => { if ( ! doc . exists ) { transaction . set ( docRef , { [ numberField ] : 1 } ) ; return 1 ; } const newNumber = typeof doc . data ( ) [ numberField ] === 'undefined' ? 1 : doc . data ( ) [ numberField ] + 1 ; await transaction . update ( docRef , { [ numberField

Reusable Code for Execute Any DB Access Code in Transaction In this post, I will show you highly reusable utility code for wrapping and executing original db access code in transaction. Anyway let's show you the code. function executeInTransaction(callable $func) { $conn = new PDO(SERVER_NAME, USERNAME, PASSWORD, DBNAME); try { $conn->beginTransaction(); $func($conn); $conn->commit(); } catch (Exception $ex) { $conn->rollBack(); throw $ex; } } Oh, how to use? You just simply passing your core DB access code as the callable $func argument. Okay, let me show you example in next section. Example Usage First, assume you have following 2 methods for inserting data to DB. CONST SERVER_NAME = 'localhost'; CONST USERNAME = "username"; CONST PASSWORD = "password"; CONS