Transaction

create(documentRef, data) → Transaction

Create the document referred to by the provided DocumentReference. The operation will fail the transaction if a document exists at the specified location.

firestore.runTransaction(transaction => {
  let documentRef = firestore.doc('col/doc');
  return transaction.get(documentRef).then(doc => {
    if (!doc.exists) {
      transaction.create(documentRef, { foo: 'bar' });
    }
  });
});

Returns

Transaction 

This Transaction instance. Used for chaining method calls.

delete(documentRef[, precondition]) → Transaction

Deletes the document referred to by the provided [DocumentReference] DocumentReference.

firestore.runTransaction(transaction => {
  let documentRef = firestore.doc('col/doc');
  transaction.delete(documentRef);
  return Promise.resolve();
});

Returns

Transaction 

This Transaction instance. Used for chaining method calls.

get(refOrQuery) → Promise

Retrieve a document or a query result from the database. Holds a pessimistic lock on all returned documents.

firestore.runTransaction(transaction => {
  let documentRef = firestore.doc('col/doc');
  return transaction.get(documentRef).then(doc => {
    if (doc.exists) {
      transaction.update(documentRef, { count: doc.get('count') + 1 });
    } else {
      transaction.create(documentRef, { count: 1 });
    }
  });
});

Returns

Promise 

A Promise that resolves with a DocumentSnapshot or QuerySnapshot for the returned documents.

getAll(...documentRefsOrReadOptions) → Promise containing Array of DocumentSnapshot

Retrieves multiple documents from Firestore. Holds a pessimistic lock on all returned documents.

The first argument is required and must be of type DocumentReference followed by any additional DocumentReference documents. If used, the optional ReadOptions must be the last argument.

let firstDoc = firestore.doc('col/doc1');
let secondDoc = firestore.doc('col/doc2');
let resultDoc = firestore.doc('col/doc3');

firestore.runTransaction(transaction => {
  return transaction.getAll(firstDoc, secondDoc).then(docs => {
    transaction.set(resultDoc, {
      sum: docs[0].get('count') + docs[1].get('count')
    });
  });
});

Returns

Promise containing Array of DocumentSnapshot 

A Promise that contains an array with the resulting document snapshots.

set(documentRef, data[, options]) → Transaction

Writes to the document referred to by the provided DocumentReference. If the document does not exist yet, it will be created. If you pass SetOptions, the provided data can be merged into the existing document.

firestore.runTransaction(transaction => {
  let documentRef = firestore.doc('col/doc');
  transaction.set(documentRef, { foo: 'bar' });
  return Promise.resolve();
});

Returns

Transaction 

This Transaction instance. Used for chaining method calls.

update(documentRef, dataOrField, ...preconditionOrValues) → Transaction

Updates fields in the document referred to by the provided DocumentReference. The update will fail if applied to a document that does not exist.

The update() method accepts either an object with field paths encoded as keys and field values encoded as values, or a variable number of arguments that alternate between field paths and field values. Nested fields can be updated by providing dot-separated field path strings or by providing FieldPath objects.

A Precondition restricting this update can be specified as the last argument.

firestore.runTransaction(transaction => {
  let documentRef = firestore.doc('col/doc');
  return transaction.get(documentRef).then(doc => {
    if (doc.exists) {
      transaction.update(documentRef, { count: doc.get('count') + 1 });
    } else {
      transaction.create(documentRef, { count: 1 });
    }
  });
});

Returns

Transaction 

This Transaction instance. Used for chaining method calls.