def _make_txn_selector(self):
"""Helper for :meth:`read`."""
if self._transaction_id is not None:
return TransactionSelector(id=self._transaction_id)
if self._read_timestamp:
key = 'read_timestamp'
value = _datetime_to_pb_timestamp(self._read_timestamp)
elif self._min_read_timestamp:
key = 'min_read_timestamp'
value = _datetime_to_pb_timestamp(self._min_read_timestamp)
elif self._max_staleness:
key = 'max_staleness'
value = _timedelta_to_duration_pb(self._max_staleness)
elif self._exact_staleness:
key = 'exact_staleness'
value = _timedelta_to_duration_pb(self._exact_staleness)
else:
key = 'strong'
value = True
options = TransactionOptions(
read_only=TransactionOptions.ReadOnly(**{key: value}))
if self._multi_use:
return TransactionSelector(begin=options)
else:
return TransactionSelector(single_use=options)
def _make_txn_selector(self):
from google.cloud.proto.spanner.v1.transaction_pb2 import (
TransactionOptions, TransactionSelector)
options = TransactionOptions(
read_only=TransactionOptions.ReadOnly(strong=True))
return TransactionSelector(single_use=options)
def begin(self):
"""Begin a transaction on the database.
:rtype: bytes
:returns: the ID for the newly-begun transaction.
:raises: ValueError if the transaction is already begun, committed,
or rolled back.
"""
if self._id is not None:
raise ValueError("Transaction already begun")
if self.committed is not None:
raise ValueError("Transaction already committed")
if self._rolled_back:
raise ValueError("Transaction is already rolled back")
database = self._session._database
api = database.spanner_api
options = _options_with_prefix(database.name)
txn_options = TransactionOptions(
read_write=TransactionOptions.ReadWrite())
response = api.begin_transaction(self._session.name,
txn_options,
options=options)
self._id = response.id
return self._id
def _make_txn_selector(self):
from google.cloud.proto.spanner.v1.transaction_pb2 import (
TransactionOptions, TransactionSelector)
if self._transaction_id:
return TransactionSelector(id=self._transaction_id)
options = TransactionOptions(
read_only=TransactionOptions.ReadOnly(strong=True))
if self._multi_use:
return TransactionSelector(begin=options)
return TransactionSelector(single_use=options)
def commit(self):
"""Commit mutations to the database.
:rtype: datetime
:returns: timestamp of the committed changes.
"""
self._check_state()
database = self._session._database
api = database.spanner_api
options = _options_with_prefix(database.name)
txn_options = TransactionOptions(
read_write=TransactionOptions.ReadWrite())
response = api.commit(self._session.name,
self._mutations,
single_use_transaction=txn_options,
options=options)
self.committed = _pb_timestamp_to_datetime(response.commit_timestamp)
return self.committed