1401 lines
50 KiB
Python
1401 lines
50 KiB
Python
# Copyright 2013-2016 DataStax, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import copy
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from datetime import datetime, timedelta
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import time
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import six
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from warnings import warn
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from cassandra.cqlengine import columns, CQLEngineException, ValidationError, UnicodeMixin
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from cassandra.cqlengine import connection
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from cassandra.cqlengine.functions import Token, BaseQueryFunction, QueryValue
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from cassandra.cqlengine.operators import (InOperator, EqualsOperator, GreaterThanOperator,
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GreaterThanOrEqualOperator, LessThanOperator,
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LessThanOrEqualOperator, ContainsOperator, BaseWhereOperator)
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from cassandra.cqlengine.statements import (WhereClause, SelectStatement, DeleteStatement,
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UpdateStatement, AssignmentClause, InsertStatement,
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BaseCQLStatement, MapUpdateClause, MapDeleteClause,
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ListUpdateClause, SetUpdateClause, CounterUpdateClause,
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ConditionalClause)
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class QueryException(CQLEngineException):
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pass
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class IfNotExistsWithCounterColumn(CQLEngineException):
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pass
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class IfExistsWithCounterColumn(CQLEngineException):
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pass
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class LWTException(CQLEngineException):
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"""Lightweight conditional exception.
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This exception will be raised when a write using an `IF` clause could not be
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applied due to existing data violating the condition. The existing data is
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available through the ``existing`` attribute.
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:param existing: The current state of the data which prevented the write.
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"""
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def __init__(self, existing):
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super(LWTException, self).__init__("LWT Query was not applied")
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self.existing = existing
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class DoesNotExist(QueryException):
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pass
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class MultipleObjectsReturned(QueryException):
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pass
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def check_applied(result):
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"""
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Raises LWTException if it looks like a failed LWT request.
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"""
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try:
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applied = result.was_applied
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except Exception:
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applied = True # result was not LWT form
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if not applied:
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raise LWTException(result[0])
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class AbstractQueryableColumn(UnicodeMixin):
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"""
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exposes cql query operators through pythons
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builtin comparator symbols
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"""
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def _get_column(self):
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raise NotImplementedError
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def __unicode__(self):
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raise NotImplementedError
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def _to_database(self, val):
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if isinstance(val, QueryValue):
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return val
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else:
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return self._get_column().to_database(val)
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def in_(self, item):
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"""
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Returns an in operator
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used where you'd typically want to use python's `in` operator
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"""
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return WhereClause(six.text_type(self), InOperator(), item)
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def contains_(self, item):
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"""
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Returns a CONTAINS operator
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"""
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return WhereClause(six.text_type(self), ContainsOperator(), item)
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def __eq__(self, other):
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return WhereClause(six.text_type(self), EqualsOperator(), self._to_database(other))
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def __gt__(self, other):
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return WhereClause(six.text_type(self), GreaterThanOperator(), self._to_database(other))
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def __ge__(self, other):
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return WhereClause(six.text_type(self), GreaterThanOrEqualOperator(), self._to_database(other))
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def __lt__(self, other):
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return WhereClause(six.text_type(self), LessThanOperator(), self._to_database(other))
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def __le__(self, other):
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return WhereClause(six.text_type(self), LessThanOrEqualOperator(), self._to_database(other))
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class BatchType(object):
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Unlogged = 'UNLOGGED'
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Counter = 'COUNTER'
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class BatchQuery(object):
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"""
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Handles the batching of queries
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http://www.datastax.com/docs/1.2/cql_cli/cql/BATCH
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"""
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warn_multiple_exec = True
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_consistency = None
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def __init__(self, batch_type=None, timestamp=None, consistency=None, execute_on_exception=False,
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timeout=connection.NOT_SET):
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"""
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:param batch_type: (optional) One of batch type values available through BatchType enum
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:type batch_type: str or None
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:param timestamp: (optional) A datetime or timedelta object with desired timestamp to be applied
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to the batch conditional.
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:type timestamp: datetime or timedelta or None
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:param consistency: (optional) One of consistency values ("ANY", "ONE", "QUORUM" etc)
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:type consistency: The :class:`.ConsistencyLevel` to be used for the batch query, or None.
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:param execute_on_exception: (Defaults to False) Indicates that when the BatchQuery instance is used
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as a context manager the queries accumulated within the context must be executed despite
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encountering an error within the context. By default, any exception raised from within
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the context scope will cause the batched queries not to be executed.
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:type execute_on_exception: bool
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:param timeout: (optional) Timeout for the entire batch (in seconds), if not specified fallback
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to default session timeout
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:type timeout: float or None
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"""
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self.queries = []
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self.batch_type = batch_type
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if timestamp is not None and not isinstance(timestamp, (datetime, timedelta)):
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raise CQLEngineException('timestamp object must be an instance of datetime')
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self.timestamp = timestamp
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self._consistency = consistency
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self._execute_on_exception = execute_on_exception
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self._timeout = timeout
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self._callbacks = []
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self._executed = False
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self._context_entered = False
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def add_query(self, query):
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if not isinstance(query, BaseCQLStatement):
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raise CQLEngineException('only BaseCQLStatements can be added to a batch query')
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self.queries.append(query)
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def consistency(self, consistency):
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self._consistency = consistency
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def _execute_callbacks(self):
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for callback, args, kwargs in self._callbacks:
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callback(*args, **kwargs)
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def add_callback(self, fn, *args, **kwargs):
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"""Add a function and arguments to be passed to it to be executed after the batch executes.
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A batch can support multiple callbacks.
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Note, that if the batch does not execute, the callbacks are not executed.
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A callback, thus, is an "on batch success" handler.
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:param fn: Callable object
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:type fn: callable
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:param *args: Positional arguments to be passed to the callback at the time of execution
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:param **kwargs: Named arguments to be passed to the callback at the time of execution
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"""
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if not callable(fn):
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raise ValueError("Value for argument 'fn' is {0} and is not a callable object.".format(type(fn)))
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self._callbacks.append((fn, args, kwargs))
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def execute(self):
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if self._executed and self.warn_multiple_exec:
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msg = "Batch executed multiple times."
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if self._context_entered:
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msg += " If using the batch as a context manager, there is no need to call execute directly."
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warn(msg)
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self._executed = True
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if len(self.queries) == 0:
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# Empty batch is a no-op
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# except for callbacks
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self._execute_callbacks()
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return
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opener = 'BEGIN ' + (self.batch_type + ' ' if self.batch_type else '') + ' BATCH'
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if self.timestamp:
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if isinstance(self.timestamp, six.integer_types):
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ts = self.timestamp
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elif isinstance(self.timestamp, (datetime, timedelta)):
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ts = self.timestamp
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if isinstance(self.timestamp, timedelta):
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ts += datetime.now() # Apply timedelta
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ts = int(time.mktime(ts.timetuple()) * 1e+6 + ts.microsecond)
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else:
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raise ValueError("Batch expects a long, a timedelta, or a datetime")
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opener += ' USING TIMESTAMP {0}'.format(ts)
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query_list = [opener]
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parameters = {}
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ctx_counter = 0
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for query in self.queries:
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query.update_context_id(ctx_counter)
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ctx = query.get_context()
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ctx_counter += len(ctx)
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query_list.append(' ' + str(query))
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parameters.update(ctx)
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query_list.append('APPLY BATCH;')
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tmp = connection.execute('\n'.join(query_list), parameters, self._consistency, self._timeout)
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check_applied(tmp)
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self.queries = []
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self._execute_callbacks()
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def __enter__(self):
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self._context_entered = True
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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# don't execute if there was an exception by default
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if exc_type is not None and not self._execute_on_exception:
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return
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self.execute()
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class AbstractQuerySet(object):
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def __init__(self, model):
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super(AbstractQuerySet, self).__init__()
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self.model = model
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# Where clause filters
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self._where = []
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# Conditional clause filters
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self._conditional = []
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# ordering arguments
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self._order = []
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self._allow_filtering = False
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# CQL has a default limit of 10000, it's defined here
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# because explicit is better than implicit
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self._limit = 10000
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# see the defer and only methods
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self._defer_fields = []
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self._only_fields = []
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self._values_list = False
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self._flat_values_list = False
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# results cache
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self._result_cache = None
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self._result_idx = None
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self._result_generator = None
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self._materialize_results = True
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self._distinct_fields = None
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self._count = None
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self._batch = None
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self._ttl = getattr(model, '__default_ttl__', None)
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self._consistency = None
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self._timestamp = None
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self._if_not_exists = False
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self._timeout = connection.NOT_SET
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self._if_exists = False
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self._fetch_size = None
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@property
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def column_family_name(self):
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return self.model.column_family_name()
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def _execute(self, q):
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if self._batch:
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return self._batch.add_query(q)
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else:
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result = connection.execute(q, consistency_level=self._consistency, timeout=self._timeout)
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if self._if_not_exists or self._if_exists or self._conditional:
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check_applied(result)
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return result
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def __unicode__(self):
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return six.text_type(self._select_query())
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def __str__(self):
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return str(self.__unicode__())
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def __call__(self, *args, **kwargs):
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return self.filter(*args, **kwargs)
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def __deepcopy__(self, memo):
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clone = self.__class__(self.model)
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for k, v in self.__dict__.items():
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if k in ['_con', '_cur', '_result_cache', '_result_idx', '_result_generator']: # don't clone these
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clone.__dict__[k] = None
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elif k == '_batch':
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# we need to keep the same batch instance across
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# all queryset clones, otherwise the batched queries
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# fly off into other batch instances which are never
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# executed, thx @dokai
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clone.__dict__[k] = self._batch
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elif k == '_timeout':
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clone.__dict__[k] = self._timeout
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else:
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clone.__dict__[k] = copy.deepcopy(v, memo)
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return clone
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def __len__(self):
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self._execute_query()
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return self.count()
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# ----query generation / execution----
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def _select_fields(self):
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""" returns the fields to select """
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return []
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def _validate_select_where(self):
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""" put select query validation here """
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def _select_query(self):
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"""
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Returns a select clause based on the given filter args
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"""
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if self._where:
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self._validate_select_where()
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return SelectStatement(
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self.column_family_name,
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fields=self._select_fields(),
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where=self._where,
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order_by=self._order,
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limit=self._limit,
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allow_filtering=self._allow_filtering,
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distinct_fields=self._distinct_fields,
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fetch_size=self._fetch_size
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)
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# ----Reads------
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def _execute_query(self):
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if self._batch:
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raise CQLEngineException("Only inserts, updates, and deletes are available in batch mode")
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if self._result_cache is None:
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self._result_generator = (i for i in self._execute(self._select_query()))
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self._result_cache = []
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self._construct_result = self._get_result_constructor()
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# "DISTINCT COUNT()" is not supported in C* < 2.2, so we need to materialize all results to get
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# len() and count() working with DISTINCT queries
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if self._materialize_results or self._distinct_fields:
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self._fill_result_cache()
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def _fill_result_cache(self):
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"""
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Fill the result cache with all results.
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"""
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idx = 0
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try:
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while True:
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idx += 1000
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self._fill_result_cache_to_idx(idx)
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except StopIteration:
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pass
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self._count = len(self._result_cache)
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def _fill_result_cache_to_idx(self, idx):
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self._execute_query()
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if self._result_idx is None:
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self._result_idx = -1
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qty = idx - self._result_idx
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if qty < 1:
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return
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else:
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for idx in range(qty):
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self._result_idx += 1
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while True:
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try:
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self._result_cache[self._result_idx] = self._construct_result(self._result_cache[self._result_idx])
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break
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except IndexError:
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self._result_cache.append(next(self._result_generator))
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def __iter__(self):
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self._execute_query()
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idx = 0
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while True:
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if len(self._result_cache) <= idx:
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try:
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self._result_cache.append(next(self._result_generator))
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except StopIteration:
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break
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instance = self._result_cache[idx]
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if isinstance(instance, dict):
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self._fill_result_cache_to_idx(idx)
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yield self._result_cache[idx]
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idx += 1
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def __getitem__(self, s):
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self._execute_query()
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if isinstance(s, slice):
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start = s.start if s.start else 0
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# calculate the amount of results that need to be loaded
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end = s.stop
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if start < 0 or s.stop is None or s.stop < 0:
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end = self.count()
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try:
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self._fill_result_cache_to_idx(end)
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except StopIteration:
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pass
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return self._result_cache[start:s.stop:s.step]
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else:
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try:
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s = int(s)
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except (ValueError, TypeError):
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raise TypeError('QuerySet indices must be integers')
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# Using negative indexing is costly since we have to execute a count()
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if s < 0:
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num_results = self.count()
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s += num_results
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try:
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self._fill_result_cache_to_idx(s)
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except StopIteration:
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raise IndexError
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return self._result_cache[s]
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def _get_result_constructor(self):
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"""
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Returns a function that will be used to instantiate query results
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"""
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raise NotImplementedError
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def batch(self, batch_obj):
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"""
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Set a batch object to run the query on.
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Note: running a select query with a batch object will raise an exception
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"""
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if batch_obj is not None and not isinstance(batch_obj, BatchQuery):
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raise CQLEngineException('batch_obj must be a BatchQuery instance or None')
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clone = copy.deepcopy(self)
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clone._batch = batch_obj
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return clone
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def first(self):
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try:
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return six.next(iter(self))
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except StopIteration:
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return None
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def all(self):
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"""
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Returns a queryset matching all rows
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|
.. code-block:: python
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for user in User.objects().all():
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print(user)
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"""
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return copy.deepcopy(self)
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def consistency(self, consistency):
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"""
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Sets the consistency level for the operation. See :class:`.ConsistencyLevel`.
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.. code-block:: python
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for user in User.objects(id=3).consistency(CL.ONE):
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print(user)
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"""
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clone = copy.deepcopy(self)
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clone._consistency = consistency
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return clone
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|
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def _parse_filter_arg(self, arg):
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"""
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Parses a filter arg in the format:
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<colname>__<op>
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:returns: colname, op tuple
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"""
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statement = arg.rsplit('__', 1)
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if len(statement) == 1:
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return arg, None
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elif len(statement) == 2:
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return statement[0], statement[1]
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else:
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raise QueryException("Can't parse '{0}'".format(arg))
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def iff(self, *args, **kwargs):
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"""Adds IF statements to queryset"""
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if len([x for x in kwargs.values() if x is None]):
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raise CQLEngineException("None values on iff are not allowed")
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|
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clone = copy.deepcopy(self)
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for operator in args:
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if not isinstance(operator, ConditionalClause):
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raise QueryException('{0} is not a valid query operator'.format(operator))
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clone._conditional.append(operator)
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|
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for col_name, val in kwargs.items():
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exists = False
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try:
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column = self.model._get_column(col_name)
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except KeyError:
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if col_name == 'pk__token':
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if not isinstance(val, Token):
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raise QueryException("Virtual column 'pk__token' may only be compared to Token() values")
|
|
column = columns._PartitionKeysToken(self.model)
|
|
else:
|
|
raise QueryException("Can't resolve column name: '{0}'".format(col_name))
|
|
|
|
if isinstance(val, Token):
|
|
if col_name != 'pk__token':
|
|
raise QueryException("Token() values may only be compared to the 'pk__token' virtual column")
|
|
partition_columns = column.partition_columns
|
|
if len(partition_columns) != len(val.value):
|
|
raise QueryException(
|
|
'Token() received {0} arguments but model has {1} partition keys'.format(
|
|
len(val.value), len(partition_columns)))
|
|
val.set_columns(partition_columns)
|
|
|
|
if isinstance(val, BaseQueryFunction) or exists is True:
|
|
query_val = val
|
|
else:
|
|
query_val = column.to_database(val)
|
|
|
|
clone._conditional.append(ConditionalClause(col_name, query_val))
|
|
|
|
return clone
|
|
|
|
def filter(self, *args, **kwargs):
|
|
"""
|
|
Adds WHERE arguments to the queryset, returning a new queryset
|
|
|
|
See :ref:`retrieving-objects-with-filters`
|
|
|
|
Returns a QuerySet filtered on the keyword arguments
|
|
"""
|
|
# add arguments to the where clause filters
|
|
if len([x for x in kwargs.values() if x is None]):
|
|
raise CQLEngineException("None values on filter are not allowed")
|
|
|
|
clone = copy.deepcopy(self)
|
|
for operator in args:
|
|
if not isinstance(operator, WhereClause):
|
|
raise QueryException('{0} is not a valid query operator'.format(operator))
|
|
clone._where.append(operator)
|
|
|
|
for arg, val in kwargs.items():
|
|
col_name, col_op = self._parse_filter_arg(arg)
|
|
quote_field = True
|
|
# resolve column and operator
|
|
try:
|
|
column = self.model._get_column(col_name)
|
|
except KeyError:
|
|
if col_name == 'pk__token':
|
|
if not isinstance(val, Token):
|
|
raise QueryException("Virtual column 'pk__token' may only be compared to Token() values")
|
|
column = columns._PartitionKeysToken(self.model)
|
|
quote_field = False
|
|
else:
|
|
raise QueryException("Can't resolve column name: '{0}'".format(col_name))
|
|
|
|
if isinstance(val, Token):
|
|
if col_name != 'pk__token':
|
|
raise QueryException("Token() values may only be compared to the 'pk__token' virtual column")
|
|
partition_columns = column.partition_columns
|
|
if len(partition_columns) != len(val.value):
|
|
raise QueryException(
|
|
'Token() received {0} arguments but model has {1} partition keys'.format(
|
|
len(val.value), len(partition_columns)))
|
|
val.set_columns(partition_columns)
|
|
|
|
# get query operator, or use equals if not supplied
|
|
operator_class = BaseWhereOperator.get_operator(col_op or 'EQ')
|
|
operator = operator_class()
|
|
|
|
if isinstance(operator, InOperator):
|
|
if not isinstance(val, (list, tuple)):
|
|
raise QueryException('IN queries must use a list/tuple value')
|
|
query_val = [column.to_database(v) for v in val]
|
|
elif isinstance(val, BaseQueryFunction):
|
|
query_val = val
|
|
elif (isinstance(operator, ContainsOperator) and
|
|
isinstance(column, (columns.List, columns.Set, columns.Map))):
|
|
# For ContainsOperator and collections, we query using the value, not the container
|
|
query_val = val
|
|
else:
|
|
query_val = column.to_database(val)
|
|
|
|
clone._where.append(WhereClause(column.db_field_name, operator, query_val, quote_field=quote_field))
|
|
|
|
return clone
|
|
|
|
def get(self, *args, **kwargs):
|
|
"""
|
|
Returns a single instance matching this query, optionally with additional filter kwargs.
|
|
|
|
See :ref:`retrieving-objects-with-filters`
|
|
|
|
Returns a single object matching the QuerySet.
|
|
|
|
.. code-block:: python
|
|
|
|
user = User.get(id=1)
|
|
|
|
If no objects are matched, a :class:`~.DoesNotExist` exception is raised.
|
|
|
|
If more than one object is found, a :class:`~.MultipleObjectsReturned` exception is raised.
|
|
"""
|
|
if args or kwargs:
|
|
return self.filter(*args, **kwargs).get()
|
|
|
|
self._execute_query()
|
|
|
|
# Check that the resultset only contains one element, avoiding sending a COUNT query
|
|
try:
|
|
self[1]
|
|
raise self.model.MultipleObjectsReturned('Multiple objects found')
|
|
except IndexError:
|
|
pass
|
|
|
|
try:
|
|
obj = self[0]
|
|
except IndexError:
|
|
raise self.model.DoesNotExist
|
|
|
|
return obj
|
|
|
|
def _get_ordering_condition(self, colname):
|
|
order_type = 'DESC' if colname.startswith('-') else 'ASC'
|
|
colname = colname.replace('-', '')
|
|
|
|
return colname, order_type
|
|
|
|
def order_by(self, *colnames):
|
|
"""
|
|
Sets the column(s) to be used for ordering
|
|
|
|
Default order is ascending, prepend a '-' to any column name for descending
|
|
|
|
*Note: column names must be a clustering key*
|
|
|
|
.. code-block:: python
|
|
|
|
from uuid import uuid1,uuid4
|
|
|
|
class Comment(Model):
|
|
photo_id = UUID(primary_key=True)
|
|
comment_id = TimeUUID(primary_key=True, default=uuid1) # second primary key component is a clustering key
|
|
comment = Text()
|
|
|
|
sync_table(Comment)
|
|
|
|
u = uuid4()
|
|
for x in range(5):
|
|
Comment.create(photo_id=u, comment="test %d" % x)
|
|
|
|
print("Normal")
|
|
for comment in Comment.objects(photo_id=u):
|
|
print comment.comment_id
|
|
|
|
print("Reversed")
|
|
for comment in Comment.objects(photo_id=u).order_by("-comment_id"):
|
|
print comment.comment_id
|
|
"""
|
|
if len(colnames) == 0:
|
|
clone = copy.deepcopy(self)
|
|
clone._order = []
|
|
return clone
|
|
|
|
conditions = []
|
|
for colname in colnames:
|
|
conditions.append('"{0}" {1}'.format(*self._get_ordering_condition(colname)))
|
|
|
|
clone = copy.deepcopy(self)
|
|
clone._order.extend(conditions)
|
|
return clone
|
|
|
|
def count(self):
|
|
"""
|
|
Returns the number of rows matched by this query.
|
|
|
|
*Note: This function executes a SELECT COUNT() and has a performance cost on large datasets*
|
|
"""
|
|
if self._batch:
|
|
raise CQLEngineException("Only inserts, updates, and deletes are available in batch mode")
|
|
|
|
if self._count is None:
|
|
query = self._select_query()
|
|
query.count = True
|
|
result = self._execute(query)
|
|
count_row = result[0].popitem()
|
|
self._count = count_row[1]
|
|
return self._count
|
|
|
|
def distinct(self, distinct_fields=None):
|
|
"""
|
|
Returns the DISTINCT rows matched by this query.
|
|
|
|
distinct_fields default to the partition key fields if not specified.
|
|
|
|
*Note: distinct_fields must be a partition key or a static column*
|
|
|
|
.. code-block:: python
|
|
|
|
class Automobile(Model):
|
|
manufacturer = columns.Text(partition_key=True)
|
|
year = columns.Integer(primary_key=True)
|
|
model = columns.Text(primary_key=True)
|
|
price = columns.Decimal()
|
|
|
|
sync_table(Automobile)
|
|
|
|
# create rows
|
|
|
|
Automobile.objects.distinct()
|
|
|
|
# or
|
|
|
|
Automobile.objects.distinct(['manufacturer'])
|
|
|
|
"""
|
|
|
|
clone = copy.deepcopy(self)
|
|
if distinct_fields:
|
|
clone._distinct_fields = distinct_fields
|
|
else:
|
|
clone._distinct_fields = [x.column_name for x in self.model._partition_keys.values()]
|
|
|
|
return clone
|
|
|
|
def limit(self, v):
|
|
"""
|
|
Limits the number of results returned by Cassandra. Use *0* or *None* to disable.
|
|
|
|
*Note that CQL's default limit is 10,000, so all queries without a limit set explicitly will have an implicit limit of 10,000*
|
|
|
|
.. code-block:: python
|
|
|
|
# Fetch 100 users
|
|
for user in User.objects().limit(100):
|
|
print(user)
|
|
|
|
# Fetch all users
|
|
for user in User.objects().limit(None):
|
|
print(user)
|
|
"""
|
|
|
|
if v is None:
|
|
v = 0
|
|
|
|
if not isinstance(v, six.integer_types):
|
|
raise TypeError
|
|
if v == self._limit:
|
|
return self
|
|
|
|
if v < 0:
|
|
raise QueryException("Negative limit is not allowed")
|
|
|
|
clone = copy.deepcopy(self)
|
|
clone._limit = v
|
|
return clone
|
|
|
|
def fetch_size(self, v):
|
|
"""
|
|
Sets the number of rows that are fetched at a time.
|
|
|
|
*Note that driver's default fetch size is 5000.*
|
|
|
|
.. code-block:: python
|
|
|
|
for user in User.objects().fetch_size(500):
|
|
print(user)
|
|
"""
|
|
|
|
if not isinstance(v, six.integer_types):
|
|
raise TypeError
|
|
if v == self._fetch_size:
|
|
return self
|
|
|
|
if v < 1:
|
|
raise QueryException("fetch size less than 1 is not allowed")
|
|
|
|
clone = copy.deepcopy(self)
|
|
clone._fetch_size = v
|
|
return clone
|
|
|
|
def allow_filtering(self):
|
|
"""
|
|
Enables the (usually) unwise practive of querying on a clustering key without also defining a partition key
|
|
"""
|
|
clone = copy.deepcopy(self)
|
|
clone._allow_filtering = True
|
|
return clone
|
|
|
|
def _only_or_defer(self, action, fields):
|
|
clone = copy.deepcopy(self)
|
|
if clone._defer_fields or clone._only_fields:
|
|
raise QueryException("QuerySet already has only or defer fields defined")
|
|
|
|
# check for strange fields
|
|
missing_fields = [f for f in fields if f not in self.model._columns.keys()]
|
|
if missing_fields:
|
|
raise QueryException(
|
|
"Can't resolve fields {0} in {1}".format(
|
|
', '.join(missing_fields), self.model.__name__))
|
|
|
|
if action == 'defer':
|
|
clone._defer_fields = fields
|
|
elif action == 'only':
|
|
clone._only_fields = fields
|
|
else:
|
|
raise ValueError
|
|
|
|
return clone
|
|
|
|
def only(self, fields):
|
|
""" Load only these fields for the returned query """
|
|
return self._only_or_defer('only', fields)
|
|
|
|
def defer(self, fields):
|
|
""" Don't load these fields for the returned query """
|
|
return self._only_or_defer('defer', fields)
|
|
|
|
def create(self, **kwargs):
|
|
return self.model(**kwargs) \
|
|
.batch(self._batch) \
|
|
.ttl(self._ttl) \
|
|
.consistency(self._consistency) \
|
|
.if_not_exists(self._if_not_exists) \
|
|
.timestamp(self._timestamp) \
|
|
.if_exists(self._if_exists) \
|
|
.save()
|
|
|
|
def delete(self):
|
|
"""
|
|
Deletes the contents of a query
|
|
"""
|
|
# validate where clause
|
|
partition_keys = set(x.db_field_name for x in self.model._partition_keys.values())
|
|
if partition_keys - set(c.field for c in self._where):
|
|
raise QueryException("The partition key must be defined on delete queries")
|
|
|
|
dq = DeleteStatement(
|
|
self.column_family_name,
|
|
where=self._where,
|
|
timestamp=self._timestamp,
|
|
conditionals=self._conditional,
|
|
if_exists=self._if_exists
|
|
)
|
|
self._execute(dq)
|
|
|
|
def __eq__(self, q):
|
|
if len(self._where) == len(q._where):
|
|
return all([w in q._where for w in self._where])
|
|
return False
|
|
|
|
def __ne__(self, q):
|
|
return not (self != q)
|
|
|
|
def timeout(self, timeout):
|
|
"""
|
|
:param timeout: Timeout for the query (in seconds)
|
|
:type timeout: float or None
|
|
"""
|
|
clone = copy.deepcopy(self)
|
|
clone._timeout = timeout
|
|
return clone
|
|
|
|
|
|
class ResultObject(dict):
|
|
"""
|
|
adds attribute access to a dictionary
|
|
"""
|
|
|
|
def __getattr__(self, item):
|
|
try:
|
|
return self[item]
|
|
except KeyError:
|
|
raise AttributeError
|
|
|
|
|
|
class SimpleQuerySet(AbstractQuerySet):
|
|
"""
|
|
|
|
"""
|
|
|
|
def _get_result_constructor(self):
|
|
"""
|
|
Returns a function that will be used to instantiate query results
|
|
"""
|
|
def _construct_instance(values):
|
|
return ResultObject(values)
|
|
return _construct_instance
|
|
|
|
|
|
class ModelQuerySet(AbstractQuerySet):
|
|
"""
|
|
"""
|
|
def _validate_select_where(self):
|
|
""" Checks that a filterset will not create invalid select statement """
|
|
# check that there's either a =, a IN or a CONTAINS (collection) relationship with a primary key or indexed field
|
|
equal_ops = [self.model._get_column_by_db_name(w.field) for w in self._where if isinstance(w.operator, EqualsOperator)]
|
|
token_comparison = any([w for w in self._where if isinstance(w.value, Token)])
|
|
if not any([w.primary_key or w.index for w in equal_ops]) and not token_comparison and not self._allow_filtering:
|
|
raise QueryException(('Where clauses require either =, a IN or a CONTAINS (collection) '
|
|
'comparison with either a primary key or indexed field'))
|
|
|
|
if not self._allow_filtering:
|
|
# if the query is not on an indexed field
|
|
if not any([w.index for w in equal_ops]):
|
|
if not any([w.partition_key for w in equal_ops]) and not token_comparison:
|
|
raise QueryException('Filtering on a clustering key without a partition key is not allowed unless allow_filtering() is called on the querset')
|
|
|
|
def _select_fields(self):
|
|
if self._defer_fields or self._only_fields:
|
|
fields = self.model._columns.keys()
|
|
if self._defer_fields:
|
|
fields = [f for f in fields if f not in self._defer_fields]
|
|
elif self._only_fields:
|
|
fields = self._only_fields
|
|
return [self.model._columns[f].db_field_name for f in fields]
|
|
return super(ModelQuerySet, self)._select_fields()
|
|
|
|
def _get_result_constructor(self):
|
|
""" Returns a function that will be used to instantiate query results """
|
|
if not self._values_list: # we want models
|
|
return lambda rows: self.model._construct_instance(rows)
|
|
elif self._flat_values_list: # the user has requested flattened list (1 value per row)
|
|
return lambda row: row.popitem()[1]
|
|
else:
|
|
return lambda row: self._get_row_value_list(self._only_fields, row)
|
|
|
|
def _get_row_value_list(self, fields, row):
|
|
result = []
|
|
for x in fields:
|
|
result.append(row[x])
|
|
return result
|
|
|
|
def _get_ordering_condition(self, colname):
|
|
colname, order_type = super(ModelQuerySet, self)._get_ordering_condition(colname)
|
|
|
|
column = self.model._columns.get(colname)
|
|
if column is None:
|
|
raise QueryException("Can't resolve the column name: '{0}'".format(colname))
|
|
|
|
# validate the column selection
|
|
if not column.primary_key:
|
|
raise QueryException(
|
|
"Can't order on '{0}', can only order on (clustered) primary keys".format(colname))
|
|
|
|
pks = [v for k, v in self.model._columns.items() if v.primary_key]
|
|
if column == pks[0]:
|
|
raise QueryException(
|
|
"Can't order by the first primary key (partition key), clustering (secondary) keys only")
|
|
|
|
return column.db_field_name, order_type
|
|
|
|
def values_list(self, *fields, **kwargs):
|
|
""" Instructs the query set to return tuples, not model instance """
|
|
flat = kwargs.pop('flat', False)
|
|
if kwargs:
|
|
raise TypeError('Unexpected keyword arguments to values_list: %s'
|
|
% (kwargs.keys(),))
|
|
if flat and len(fields) > 1:
|
|
raise TypeError("'flat' is not valid when values_list is called with more than one field.")
|
|
clone = self.only(fields)
|
|
clone._values_list = True
|
|
clone._flat_values_list = flat
|
|
return clone
|
|
|
|
def ttl(self, ttl):
|
|
"""
|
|
Sets the ttl (in seconds) for modified data.
|
|
|
|
*Note that running a select query with a ttl value will raise an exception*
|
|
"""
|
|
clone = copy.deepcopy(self)
|
|
clone._ttl = ttl
|
|
return clone
|
|
|
|
def timestamp(self, timestamp):
|
|
"""
|
|
Allows for custom timestamps to be saved with the record.
|
|
"""
|
|
clone = copy.deepcopy(self)
|
|
clone._timestamp = timestamp
|
|
return clone
|
|
|
|
def if_not_exists(self):
|
|
"""
|
|
Check the existence of an object before insertion.
|
|
|
|
If the insertion isn't applied, a LWTException is raised.
|
|
"""
|
|
if self.model._has_counter:
|
|
raise IfNotExistsWithCounterColumn('if_not_exists cannot be used with tables containing counter columns')
|
|
clone = copy.deepcopy(self)
|
|
clone._if_not_exists = True
|
|
return clone
|
|
|
|
def if_exists(self):
|
|
"""
|
|
Check the existence of an object before an update or delete.
|
|
|
|
If the update or delete isn't applied, a LWTException is raised.
|
|
"""
|
|
if self.model._has_counter:
|
|
raise IfExistsWithCounterColumn('if_exists cannot be used with tables containing counter columns')
|
|
clone = copy.deepcopy(self)
|
|
clone._if_exists = True
|
|
return clone
|
|
|
|
def update(self, **values):
|
|
"""
|
|
Performs an update on the row selected by the queryset. Include values to update in the
|
|
update like so:
|
|
|
|
.. code-block:: python
|
|
|
|
Model.objects(key=n).update(value='x')
|
|
|
|
Passing in updates for columns which are not part of the model will raise a ValidationError.
|
|
|
|
Per column validation will be performed, but instance level validation will not
|
|
(i.e., `Model.validate` is not called). This is sometimes referred to as a blind update.
|
|
|
|
For example:
|
|
|
|
.. code-block:: python
|
|
|
|
class User(Model):
|
|
id = Integer(primary_key=True)
|
|
name = Text()
|
|
|
|
setup(["localhost"], "test")
|
|
sync_table(User)
|
|
|
|
u = User.create(id=1, name="jon")
|
|
|
|
User.objects(id=1).update(name="Steve")
|
|
|
|
# sets name to null
|
|
User.objects(id=1).update(name=None)
|
|
|
|
|
|
Also supported is blindly adding and removing elements from container columns,
|
|
without loading a model instance from Cassandra.
|
|
|
|
Using the syntax `.update(column_name={x, y, z})` will overwrite the contents of the container, like updating a
|
|
non container column. However, adding `__<operation>` to the end of the keyword arg, makes the update call add
|
|
or remove items from the collection, without overwriting then entire column.
|
|
|
|
Given the model below, here are the operations that can be performed on the different container columns:
|
|
|
|
.. code-block:: python
|
|
|
|
class Row(Model):
|
|
row_id = columns.Integer(primary_key=True)
|
|
set_column = columns.Set(Integer)
|
|
list_column = columns.List(Integer)
|
|
map_column = columns.Map(Integer, Integer)
|
|
|
|
:class:`~cqlengine.columns.Set`
|
|
|
|
- `add`: adds the elements of the given set to the column
|
|
- `remove`: removes the elements of the given set to the column
|
|
|
|
|
|
.. code-block:: python
|
|
|
|
# add elements to a set
|
|
Row.objects(row_id=5).update(set_column__add={6})
|
|
|
|
# remove elements to a set
|
|
Row.objects(row_id=5).update(set_column__remove={4})
|
|
|
|
:class:`~cqlengine.columns.List`
|
|
|
|
- `append`: appends the elements of the given list to the end of the column
|
|
- `prepend`: prepends the elements of the given list to the beginning of the column
|
|
|
|
.. code-block:: python
|
|
|
|
# append items to a list
|
|
Row.objects(row_id=5).update(list_column__append=[6, 7])
|
|
|
|
# prepend items to a list
|
|
Row.objects(row_id=5).update(list_column__prepend=[1, 2])
|
|
|
|
|
|
:class:`~cqlengine.columns.Map`
|
|
|
|
- `update`: adds the given keys/values to the columns, creating new entries if they didn't exist, and overwriting old ones if they did
|
|
|
|
.. code-block:: python
|
|
|
|
# add items to a map
|
|
Row.objects(row_id=5).update(map_column__update={1: 2, 3: 4})
|
|
"""
|
|
if not values:
|
|
return
|
|
|
|
nulled_columns = set()
|
|
us = UpdateStatement(self.column_family_name, where=self._where, ttl=self._ttl,
|
|
timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists)
|
|
for name, val in values.items():
|
|
col_name, col_op = self._parse_filter_arg(name)
|
|
col = self.model._columns.get(col_name)
|
|
# check for nonexistant columns
|
|
if col is None:
|
|
raise ValidationError("{0}.{1} has no column named: {2}".format(self.__module__, self.model.__name__, col_name))
|
|
# check for primary key update attempts
|
|
if col.is_primary_key:
|
|
raise ValidationError("Cannot apply update to primary key '{0}' for {1}.{2}".format(col_name, self.__module__, self.model.__name__))
|
|
|
|
# we should not provide default values in this use case.
|
|
val = col.validate(val)
|
|
|
|
if val is None:
|
|
nulled_columns.add(col_name)
|
|
continue
|
|
|
|
# add the update statements
|
|
if isinstance(col, columns.Counter):
|
|
# TODO: implement counter updates
|
|
raise NotImplementedError
|
|
elif isinstance(col, (columns.List, columns.Set, columns.Map)):
|
|
if isinstance(col, columns.List):
|
|
klass = ListUpdateClause
|
|
elif isinstance(col, columns.Set):
|
|
klass = SetUpdateClause
|
|
elif isinstance(col, columns.Map):
|
|
klass = MapUpdateClause
|
|
else:
|
|
raise RuntimeError
|
|
us.add_assignment_clause(klass(col_name, col.to_database(val), operation=col_op))
|
|
else:
|
|
us.add_assignment_clause(AssignmentClause(
|
|
col_name, col.to_database(val)))
|
|
|
|
if us.assignments:
|
|
self._execute(us)
|
|
|
|
if nulled_columns:
|
|
ds = DeleteStatement(self.column_family_name, fields=nulled_columns,
|
|
where=self._where, conditionals=self._conditional, if_exists=self._if_exists)
|
|
self._execute(ds)
|
|
|
|
|
|
class DMLQuery(object):
|
|
"""
|
|
A query object used for queries performing inserts, updates, or deletes
|
|
|
|
this is usually instantiated by the model instance to be modified
|
|
|
|
unlike the read query object, this is mutable
|
|
"""
|
|
_ttl = None
|
|
_consistency = None
|
|
_timestamp = None
|
|
_if_not_exists = False
|
|
_if_exists = False
|
|
|
|
def __init__(self, model, instance=None, batch=None, ttl=None, consistency=None, timestamp=None,
|
|
if_not_exists=False, conditional=None, timeout=connection.NOT_SET, if_exists=False):
|
|
self.model = model
|
|
self.column_family_name = self.model.column_family_name()
|
|
self.instance = instance
|
|
self._batch = batch
|
|
self._ttl = ttl
|
|
self._consistency = consistency
|
|
self._timestamp = timestamp
|
|
self._if_not_exists = if_not_exists
|
|
self._if_exists = if_exists
|
|
self._conditional = conditional
|
|
self._timeout = timeout
|
|
|
|
def _execute(self, q):
|
|
if self._batch:
|
|
return self._batch.add_query(q)
|
|
else:
|
|
tmp = connection.execute(q, consistency_level=self._consistency, timeout=self._timeout)
|
|
if self._if_not_exists or self._if_exists or self._conditional:
|
|
check_applied(tmp)
|
|
return tmp
|
|
|
|
def batch(self, batch_obj):
|
|
if batch_obj is not None and not isinstance(batch_obj, BatchQuery):
|
|
raise CQLEngineException('batch_obj must be a BatchQuery instance or None')
|
|
self._batch = batch_obj
|
|
return self
|
|
|
|
def _delete_null_columns(self):
|
|
"""
|
|
executes a delete query to remove columns that have changed to null
|
|
"""
|
|
ds = DeleteStatement(self.column_family_name, conditionals=self._conditional, if_exists=self._if_exists)
|
|
deleted_fields = False
|
|
for _, v in self.instance._values.items():
|
|
col = v.column
|
|
if v.deleted:
|
|
ds.add_field(col.db_field_name)
|
|
deleted_fields = True
|
|
elif isinstance(col, columns.Map):
|
|
uc = MapDeleteClause(col.db_field_name, v.value, v.previous_value)
|
|
if uc.get_context_size() > 0:
|
|
ds.add_field(uc)
|
|
deleted_fields = True
|
|
|
|
if deleted_fields:
|
|
for name, col in self.model._primary_keys.items():
|
|
ds.add_where_clause(WhereClause(
|
|
col.db_field_name,
|
|
EqualsOperator(),
|
|
col.to_database(getattr(self.instance, name))
|
|
))
|
|
self._execute(ds)
|
|
|
|
def update(self):
|
|
"""
|
|
updates a row.
|
|
This is a blind update call.
|
|
All validation and cleaning needs to happen
|
|
prior to calling this.
|
|
"""
|
|
if self.instance is None:
|
|
raise CQLEngineException("DML Query intance attribute is None")
|
|
assert type(self.instance) == self.model
|
|
null_clustering_key = False if len(self.instance._clustering_keys) == 0 else True
|
|
static_changed_only = True
|
|
statement = UpdateStatement(self.column_family_name, ttl=self._ttl, timestamp=self._timestamp,
|
|
conditionals=self._conditional, if_exists=self._if_exists)
|
|
for name, col in self.instance._clustering_keys.items():
|
|
null_clustering_key = null_clustering_key and col._val_is_null(getattr(self.instance, name, None))
|
|
# get defined fields and their column names
|
|
for name, col in self.model._columns.items():
|
|
# if clustering key is null, don't include non static columns
|
|
if null_clustering_key and not col.static and not col.partition_key:
|
|
continue
|
|
if not col.is_primary_key:
|
|
val = getattr(self.instance, name, None)
|
|
val_mgr = self.instance._values[name]
|
|
|
|
if val is None:
|
|
continue
|
|
|
|
if not val_mgr.changed and not isinstance(col, columns.Counter):
|
|
continue
|
|
|
|
static_changed_only = static_changed_only and col.static
|
|
if isinstance(col, (columns.BaseContainerColumn, columns.Counter)):
|
|
# get appropriate clause
|
|
if isinstance(col, columns.List):
|
|
klass = ListUpdateClause
|
|
elif isinstance(col, columns.Map):
|
|
klass = MapUpdateClause
|
|
elif isinstance(col, columns.Set):
|
|
klass = SetUpdateClause
|
|
elif isinstance(col, columns.Counter):
|
|
klass = CounterUpdateClause
|
|
else:
|
|
raise RuntimeError
|
|
|
|
clause = klass(col.db_field_name, val,
|
|
previous=val_mgr.previous_value, column=col)
|
|
if clause.get_context_size() > 0:
|
|
statement.add_assignment_clause(clause)
|
|
else:
|
|
statement.add_assignment_clause(AssignmentClause(
|
|
col.db_field_name,
|
|
col.to_database(val)
|
|
))
|
|
|
|
if statement.assignments:
|
|
for name, col in self.model._primary_keys.items():
|
|
# only include clustering key if clustering key is not null, and non static columns are changed to avoid cql error
|
|
if (null_clustering_key or static_changed_only) and (not col.partition_key):
|
|
continue
|
|
statement.add_where_clause(WhereClause(
|
|
col.db_field_name,
|
|
EqualsOperator(),
|
|
col.to_database(getattr(self.instance, name))
|
|
))
|
|
self._execute(statement)
|
|
|
|
if not null_clustering_key:
|
|
self._delete_null_columns()
|
|
|
|
def save(self):
|
|
"""
|
|
Creates / updates a row.
|
|
This is a blind insert call.
|
|
All validation and cleaning needs to happen
|
|
prior to calling this.
|
|
"""
|
|
if self.instance is None:
|
|
raise CQLEngineException("DML Query intance attribute is None")
|
|
assert type(self.instance) == self.model
|
|
|
|
nulled_fields = set()
|
|
if self.instance._has_counter or self.instance._can_update():
|
|
if self.instance._has_counter:
|
|
warn("'create' and 'save' actions on Counters are deprecated. A future version will disallow this. Use the 'update' mechanism instead.")
|
|
return self.update()
|
|
else:
|
|
insert = InsertStatement(self.column_family_name, ttl=self._ttl, timestamp=self._timestamp, if_not_exists=self._if_not_exists)
|
|
static_save_only = False if len(self.instance._clustering_keys) == 0 else True
|
|
for name, col in self.instance._clustering_keys.items():
|
|
static_save_only = static_save_only and col._val_is_null(getattr(self.instance, name, None))
|
|
for name, col in self.instance._columns.items():
|
|
if static_save_only and not col.static and not col.partition_key:
|
|
continue
|
|
val = getattr(self.instance, name, None)
|
|
if col._val_is_null(val):
|
|
if self.instance._values[name].changed:
|
|
nulled_fields.add(col.db_field_name)
|
|
continue
|
|
insert.add_assignment_clause(AssignmentClause(
|
|
col.db_field_name,
|
|
col.to_database(getattr(self.instance, name, None))
|
|
))
|
|
|
|
# skip query execution if it's empty
|
|
# caused by pointless update queries
|
|
if not insert.is_empty:
|
|
self._execute(insert)
|
|
# delete any nulled columns
|
|
if not static_save_only:
|
|
self._delete_null_columns()
|
|
|
|
def delete(self):
|
|
""" Deletes one instance """
|
|
if self.instance is None:
|
|
raise CQLEngineException("DML Query instance attribute is None")
|
|
|
|
ds = DeleteStatement(self.column_family_name, timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists)
|
|
for name, col in self.model._primary_keys.items():
|
|
if (not col.partition_key) and (getattr(self.instance, name) is None):
|
|
continue
|
|
|
|
ds.add_where_clause(WhereClause(
|
|
col.db_field_name,
|
|
EqualsOperator(),
|
|
col.to_database(getattr(self.instance, name))
|
|
))
|
|
self._execute(ds)
|