Transaction

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

new Transaction(datastore)

Parameters:
Name Type Description
datastore Datastore

A Datastore instance.
Mixes In:
  • module:datastore/request
See:
Example
```
const {Datastore} = require('@google-cloud/datastore');
const datastore = new Datastore();
const transaction = datastore.transaction();
```

Extends

  • Request

Members

datastore

namespace

Methods

createAggregationQuery()

Create an aggregation query from the query specified. See {module:datastore/query} for all of the available methods.

delete(key)

Delete all entities identified with the specified key(s) in the current transaction.

Parameters:
Name Type Description
key Key | Array.<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.
    }
  });
});
```

insert(entities)

Maps to Datastore#save, forcing the method to be insert.

Parameters:
Name Type Description
entities object | Array.<object>

Datastore key object(s).

Properties
Name Type Attributes Description
key Key

Datastore key object.
excludeFromIndexes Array.<string> <optional>

Exclude properties from indexing using a simple JSON path notation. See the examples in Datastore#save to see how to target properties at different levels of nesting within your entity.
data object

Data to save with the provided key.

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.

Parameters:
Name Type Description
entities object | Array.<object>

Datastore key object(s).

Properties
Name Type Attributes Description
key Key

Datastore key object.
excludeFromIndexes Array.<string> <optional>

Exclude properties from indexing using a simple JSON path notation. See the example below to see how to target properties at different levels of nesting within your entity.
data object

Data to save with the provided key.
Examples
```
<caption>Save a single entity.</caption>
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.
    }
  });
});

```
```
<caption>Save multiple entities at once.</caption>
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.
    }
  });
});
```

update(entities)

Maps to Datastore#save, forcing the method to be update.

Parameters:
Name Type Description
entities object | Array.<object>

Datastore key object(s).

Properties
Name Type Attributes Description
key Key

Datastore key object.
excludeFromIndexes Array.<string> <optional>

Exclude properties from indexing using a simple JSON path notation. See the examples in Datastore#save to see how to target properties at different levels of nesting within your entity.
data object

Data to save with the provided key.

upsert(entities)

Maps to Datastore#save, forcing the method to be upsert.

Parameters:
Name Type Description
entities object | Array.<object>

Datastore key object(s).

Properties
Name Type Attributes Description
key Key

Datastore key object.
excludeFromIndexes Array.<string> <optional>

Exclude properties from indexing using a simple JSON path notation. See the examples in Datastore#save to see how to target properties at different levels of nesting within your entity.
data object

Data to save with the provided key.