Class Batch (2.21.0)

An abstraction representing a collected group of updates / deletes.

Used to build up a bulk mutation.

For example, the following snippet of code will put the two save operations and the delete operation into the same mutation, and send them to the server in a single API request:

.. testsetup:: batch

 import uuid

from google.cloud import datastore 
unique = str(uuid.uuid4())[0:8]
client = datastore 
. Client 
(namespace='ns{}'.format(unique)) 

.. doctest:: batch

 >>> entity1 = datastore.Entity(client.key('EntityKind', 1234))
>>> entity2 = datastore.Entity(client.key('EntityKind', 2345))
>>> key3 = client.key('EntityKind', 3456)
>>> batch = client.batch()
>>> batch.begin()
>>> batch.put(entity1)
>>> batch.put(entity2)
>>> batch.delete(key3)
>>> batch.commit() 

You can also use a batch as a context manager, in which case commit will be called automatically if its block exits without raising an exception:

.. doctest:: batch

 >>> with client.batch() as batch:
...     batch.put(entity1)
...     batch.put(entity2)
...     batch.delete(key3) 

By default, no updates will be sent if the block exits with an error:

.. doctest:: batch

 >>> def do_some_work(batch):
...    return
>>> with client.batch() as batch:
...     do_some_work(batch)
...     raise Exception()  # rolls back
Traceback (most recent call last):
  ...
Exception 

.. testcleanup:: txn

 with client.batch() as batch:
    batch.delete(client.key('EntityKind', 1234))
    batch.delete(client.key('EntityKind', 2345)) 

Getter for database in which the batch will run.

Getter for the changes accumulated by this batch.

Every batch is committed with a single commit request containing all the work to be done as mutations. Inside a batch, calling put with an entity, or delete with a key, builds up the request by adding a new mutation. This getter returns the protobuf that has been built-up so far.

Getter for namespace in which the batch will run.

Getter for project in which the batch will run.

Begins a batch.

This method is called automatically when entering a with statement, however it can be called explicitly if you don't want to use a context manager.

Overridden by xref_Transaction.

Commits the batch.

This is called automatically upon exiting a with statement, however it can be called explicitly if you don't want to use a context manager.

Return the topmost batch / transaction, or None.

Remember a key to be deleted during commit .

Remember an entity's state to be saved during commit .

Rolls back the current batch.

Marks the batch as aborted (can't be used again).

Overridden by xref_Transaction.