Transaction

A reference to a transaction. The Transaction object passed to a transaction's updateFunction provides the methods to read and write data within the transaction context. See Firestore.runTransaction().

A transaction consists of any number of get() operations followed by any number of write operations such as set(), update(), or delete(). In the case of a concurrent edit, Cloud Firestore runs the entire transaction again. For example, if a transaction reads documents and another client modifies any of those documents, Cloud Firestore retries the transaction. This feature ensures that the transaction runs on up-to-date and consistent data.

Transactions never partially apply writes. All writes execute at the end of a successful transaction.

When using transactions, note that:

• Read operations must come before write operations.
• A function calling a transaction (transaction function) might run more than once if a concurrent edit affects a document that the transaction reads.
• Transaction functions should not directly modify application state (return a value from the updateFunction).
• Transactions will fail when the client is offline.

Methods

delete(documentRef: DocumentReference): Transaction;

get(documentRef: DocumentReference<>): Promise<DocumentSnapshot<>>;

set(documentRef: DocumentReference<>, data: , options?: SetOptions): Transaction;

update(documentRef: DocumentReference<>, data: Partial<>): Transaction;

update(documentRef: DocumentReference<>, field:  | FieldPath, value: , moreFieldsAndValues: any[]): Transaction;