Class AggregationQuery (2.10.0)

AggregationQuery(client, query)

An Aggregation query against the Cloud Datastore.

This class serves as an abstraction for creating aggregations over query in the Cloud Datastore.

Parameters
Name	Description
`client`	`Client` The client used to connect to Datastore.
`query`	`Query` The query used for aggregations.

Properties

namespace

The nested query's namespace

Returns
Type	Description
`str or None`	the namespace assigned to this query

project

Get the project for this AggregationQuery.

Returns
Type	Description
`str`	The project for the query.

Methods

add_aggregation

add_aggregation(aggregation)

Adds an aggregation operation to the nested query

Parameter
Name	Description
`aggregation`	`BaseAggregation` An aggregation operation, e.g. a CountAggregation

add_aggregations

add_aggregations(aggregations)

Adds a list of aggregations to the nested query

Parameter
Name	Description
`aggregations`	`list` a list of aggregation operations

count

count(alias=None)

Adds a count over the nested query

Parameter
Name	Description
`alias`	`str` (Optional) The alias for the count

fetch

fetch(client=None, eventual=False, retry=None, timeout=None, read_time=None)

Execute the Aggregation Query; return an iterator for the aggregation results.

For example:

.. testsetup:: aggregation-query-fetch

import uuid

from google.cloud import datastore

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

.. doctest:: aggregation-query-fetch

>>> andy = datastore.Entity(client.key('Person', 1234))
>>> andy['name'] = 'Andy'
>>> sally = datastore.Entity(client.key('Person', 2345))
>>> sally['name'] = 'Sally'
>>> bobby = datastore.Entity(client.key('Person', 3456))
>>> bobby['name'] = 'Bobby'
>>> client.put_multi([andy, sally, bobby])
>>> query = client.query(kind='Andy')
>>> aggregation_query = client.aggregation_query(query)
>>> result = aggregation_query.count(alias="total").fetch()
>>> result
<<xref uid="google.cloud.datastore.aggregation.AggregationResultIterator">google.cloud.datastore.aggregation.AggregationResultIterator</xref> object at ...>

.. testcleanup:: aggregation-query-fetch

client.delete(andy.key)

Parameters
Name	Description
`client`	`Client` (Optional) client used to connect to datastore. If not supplied, uses the query's value.
`eventual`	`bool` (Optional) Defaults to strongly consistent (False). Setting True will use eventual consistency, but cannot be used inside a transaction or with read_time, otherwise will raise ValueError.
`retry`	`google.api_core.retry.Retry` A retry object used to retry requests. If `None` is specified, requests will be retried using a default configuration.
`timeout`	`float` Time, in seconds, to wait for the request to complete. Note that if `retry` is specified, the timeout applies to each individual attempt.
`read_time`	`datetime` (Optional) use read_time read consistency, cannot be used inside a transaction or with eventual consistency, or will raise ValueError.

Returns
Type	Description
`AggregationIterator`	The iterator for the aggregation query.