Transaction
A transaction is a set of Datastore operations on one or more entities. Each transaction is guaranteed to be atomic, which means that transactions are never partially applied. Either all of the operations in the transaction are applied, or none of them are applied.
Constructor
Transaction
new Transaction(datastore)
Parameter |
|
|---|---|
|
datastore |
A Datastore instance. |
- Extends
- Request
- Mixes in
- module:datastore/request
- See also
Example
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();Properties
datastore
namespace
string
projectId
string
Methods
commit
commit(gaxOptions, callback)
Commit the remote transaction and finalize the current transaction instance.
If the commit request fails, we will automatically rollback the transaction.
Parameter |
|||||||
|---|---|---|---|---|---|---|---|
|
gaxOptions |
Optional object Request configuration options, outlined here: https://googleapis.github.io/gax-nodejs/global.html#CallOptions. |
||||||
|
callback |
function() The callback function. Values in
|
||||||
Example
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
transaction.commit((err, apiResponse) => {
if (err) {
// Transaction could not be committed.
}
});
//-
// If the callback is omitted, we'll return a Promise.
//-
transaction.commit().then((data) => {
const apiResponse = data[0];
});createQuery
createQuery(namespace, kind) returns Query
Create a query for the specified kind. See {module:datastore/query} for all of the available methods.
Parameter |
|
|---|---|
|
namespace |
Optional string Namespace. |
|
kind |
string The kind to query. |
- See also
- Query
- Returns
Example
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
// Run the query inside the transaction.
transaction.run((err) => {
if (err) {
// Error handling omitted.
}
const query = transaction.createQuery('Company');
query.run((err, entities) => {
if (err) {
// Error handling omitted.
}
transaction.commit((err) => {
if (!err) {
// Transaction committed successfully.
}
});
});
});delete
delete(key)
Delete all entities identified with the specified key(s) in the current transaction.
Parameter |
|
|---|---|
|
key |
Datastore key object(s). |
Example
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
transaction.run((err) => {
if (err) {
// Error handling omitted.
}
// Delete a single entity.
transaction.delete(datastore.key(['Company', 123]));
// Delete multiple entities at once.
transaction.delete([
datastore.key(['Company', 123]),
datastore.key(['Product', 'Computer'])
]);
transaction.commit((err) => {
if (!err) {
// Transaction committed successfully.
}
});
});rollback
rollback(gaxOptions, callback)
Reverse a transaction remotely and finalize the current transaction instance.
Parameter |
|||||||
|---|---|---|---|---|---|---|---|
|
gaxOptions |
Optional object Request configuration options, outlined here: https://googleapis.github.io/gax-nodejs/global.html#CallOptions. |
||||||
|
callback |
function() The callback function. Values in
|
||||||
Example
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
transaction.run((err) => {
if (err) {
// Error handling omitted.
}
transaction.rollback((err) => {
if (!err) {
// Transaction rolled back successfully.
}
});
});
//-
// If the callback is omitted, we'll return a Promise.
//-
transaction.rollback().then((data) => {
const apiResponse = data[0];
});run
run(options, callback)
Begin a remote transaction. In the callback provided, run your transactional commands.
Parameter |
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|---|---|---|---|---|---|---|---|---|---|
|
options |
Optional object Configuration object. Values in
|
||||||||
|
callback |
function() The function to execute within the context of a transaction. Values in
|
||||||||
Example
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
transaction.run((err, transaction) => {
// Perform Datastore transactional operations.
const key = datastore.key(['Company', 123]);
transaction.get(key, (err, entity) => {
entity.name = 'Google';
transaction.save({
key: key,
data: entity
});
transaction.commit((err) => {
if (!err) {
// Data saved successfully.
}
});
});
});
//-
// If the callback is omitted, we'll return a Promise.
//-
transaction.run().then((data) => {
const transaction = data[0];
const apiResponse = data[1];
});save
save(entities)
Insert or update the specified object(s) in the current transaction. If a key is incomplete, its associated object is inserted and the original Key object is updated to contain the generated ID.
This method will determine the correct Datastore method to execute (upsert,
insert, or update) by using the key(s) provided. For example, if you provide an incomplete key (one without an ID), the request will create a new entity and have its ID automatically assigned. If you provide a
complete key, the entity will be updated with the data specified.
By default, all properties are indexed. To prevent a property from being included in all indexes, you must supply an excludeFromIndexes array. See below for an example.
Parameter |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
|
entities |
(object or Array of object) Datastore key object(s). Values in
|
||||||||
Examples
Save a single entity.
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
// Notice that we are providing an incomplete key. After the transaction is
// committed, the Key object held by the `key` variable will be populated
// with a path containing its generated ID.
//-
const key = datastore.key('Company');
transaction.run((err) => {
if (err) {
// Error handling omitted.
}
transaction.save({
key: key,
data: {
rating: '10'
}
});
transaction.commit((err) => {
if (!err) {
// Data saved successfully.
}
});
});const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
// Use an array, `excludeFromIndexes`, to exclude properties from indexing.
// This will allow storing string values larger than 1500 bytes.
transaction.run((err) => {
if (err) {
// Error handling omitted.
}
transaction.save({
key: key,
excludeFromIndexes: [
'description',
'embeddedEntity.description',
'arrayValue[].description'
],
data: {
description: 'Long string (...)',
embeddedEntity: {
description: 'Long string (...)'
},
arrayValue: [
{
description: 'Long string (...)'
}
]
}
});
transaction.commit((err) => {
if (!err) {
// Data saved successfully.
}
});
});Save multiple entities at once.
const Datastore = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
const companyKey = datastore.key(['Company', 123]);
const productKey = datastore.key(['Product', 'Computer']);
transaction.run((err) => {
if (err) {
// Error handling omitted.
}
transaction.save([
{
key: companyKey,
data: {
HQ: 'Dallas, TX'
}
},
{
key: productKey,
data: {
vendor: 'Dell'
}
}
]);
transaction.commit((err) => {
if (!err) {
// Data saved successfully.
}
});
});