232 lines
7.9 KiB
Python
232 lines
7.9 KiB
Python
# Copyright 2019-present MongoDB, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you
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# may not use this file except in compliance with the License. You
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# 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
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# implied. See the License for the specific language governing
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# permissions and limitations under the License.
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"""Perform aggregation operations on a collection or database."""
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from bson.son import SON
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from pymongo import common
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from pymongo.collation import validate_collation_or_none
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from pymongo.errors import ConfigurationError
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from pymongo.read_preferences import ReadPreference, _AggWritePref
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class _AggregationCommand:
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"""The internal abstract base class for aggregation cursors.
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Should not be called directly by application developers. Use
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:meth:`pymongo.collection.Collection.aggregate`, or
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:meth:`pymongo.database.Database.aggregate` instead.
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"""
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def __init__(
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self,
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target,
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cursor_class,
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pipeline,
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options,
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explicit_session,
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let=None,
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user_fields=None,
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result_processor=None,
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comment=None,
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show_expanded_events=None,
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):
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if "explain" in options:
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raise ConfigurationError(
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"The explain option is not supported. Use Database.command instead."
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)
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self._target = target
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pipeline = common.validate_list("pipeline", pipeline)
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self._pipeline = pipeline
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self._performs_write = False
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if pipeline and ("$out" in pipeline[-1] or "$merge" in pipeline[-1]):
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self._performs_write = True
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common.validate_is_mapping("options", options)
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if let is not None:
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common.validate_is_mapping("let", let)
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options["let"] = let
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if comment is not None:
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options["comment"] = comment
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self._options = options
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# This is the batchSize that will be used for setting the initial
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# batchSize for the cursor, as well as the subsequent getMores.
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self._batch_size = common.validate_non_negative_integer_or_none(
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"batchSize", self._options.pop("batchSize", None)
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)
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# If the cursor option is already specified, avoid overriding it.
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self._options.setdefault("cursor", {})
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# If the pipeline performs a write, we ignore the initial batchSize
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# since the server doesn't return results in this case.
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if self._batch_size is not None and not self._performs_write:
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self._options["cursor"]["batchSize"] = self._batch_size
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self._cursor_class = cursor_class
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self._explicit_session = explicit_session
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self._user_fields = user_fields
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self._result_processor = result_processor
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self._collation = validate_collation_or_none(options.pop("collation", None))
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self._max_await_time_ms = options.pop("maxAwaitTimeMS", None)
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self._write_preference = None
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@property
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def _aggregation_target(self):
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"""The argument to pass to the aggregate command."""
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raise NotImplementedError
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@property
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def _cursor_namespace(self):
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"""The namespace in which the aggregate command is run."""
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raise NotImplementedError
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def _cursor_collection(self, cursor_doc):
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"""The Collection used for the aggregate command cursor."""
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raise NotImplementedError
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@property
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def _database(self):
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"""The database against which the aggregation command is run."""
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raise NotImplementedError
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def get_read_preference(self, session):
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if self._write_preference:
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return self._write_preference
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pref = self._target._read_preference_for(session)
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if self._performs_write and pref != ReadPreference.PRIMARY:
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self._write_preference = pref = _AggWritePref(pref)
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return pref
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def get_cursor(self, session, server, sock_info, read_preference):
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# Serialize command.
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cmd = SON([("aggregate", self._aggregation_target), ("pipeline", self._pipeline)])
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cmd.update(self._options)
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# Apply this target's read concern if:
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# readConcern has not been specified as a kwarg and either
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# - server version is >= 4.2 or
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# - server version is >= 3.2 and pipeline doesn't use $out
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if ("readConcern" not in cmd) and (
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not self._performs_write or (sock_info.max_wire_version >= 8)
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):
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read_concern = self._target.read_concern
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else:
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read_concern = None
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# Apply this target's write concern if:
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# writeConcern has not been specified as a kwarg and pipeline doesn't
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# perform a write operation
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if "writeConcern" not in cmd and self._performs_write:
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write_concern = self._target._write_concern_for(session)
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else:
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write_concern = None
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# Run command.
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result = sock_info.command(
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self._database.name,
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cmd,
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read_preference,
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self._target.codec_options,
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parse_write_concern_error=True,
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read_concern=read_concern,
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write_concern=write_concern,
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collation=self._collation,
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session=session,
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client=self._database.client,
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user_fields=self._user_fields,
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)
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if self._result_processor:
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self._result_processor(result, sock_info)
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# Extract cursor from result or mock/fake one if necessary.
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if "cursor" in result:
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cursor = result["cursor"]
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else:
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# Unacknowledged $out/$merge write. Fake a cursor.
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cursor = {
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"id": 0,
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"firstBatch": result.get("result", []),
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"ns": self._cursor_namespace,
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}
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# Create and return cursor instance.
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cmd_cursor = self._cursor_class(
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self._cursor_collection(cursor),
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cursor,
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sock_info.address,
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batch_size=self._batch_size or 0,
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max_await_time_ms=self._max_await_time_ms,
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session=session,
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explicit_session=self._explicit_session,
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comment=self._options.get("comment"),
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)
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cmd_cursor._maybe_pin_connection(sock_info)
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return cmd_cursor
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class _CollectionAggregationCommand(_AggregationCommand):
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@property
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def _aggregation_target(self):
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return self._target.name
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@property
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def _cursor_namespace(self):
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return self._target.full_name
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def _cursor_collection(self, cursor):
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"""The Collection used for the aggregate command cursor."""
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return self._target
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@property
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def _database(self):
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return self._target.database
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class _CollectionRawAggregationCommand(_CollectionAggregationCommand):
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def __init__(self, *args, **kwargs):
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super().__init__(*args, **kwargs)
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# For raw-batches, we set the initial batchSize for the cursor to 0.
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if not self._performs_write:
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self._options["cursor"]["batchSize"] = 0
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class _DatabaseAggregationCommand(_AggregationCommand):
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@property
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def _aggregation_target(self):
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return 1
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@property
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def _cursor_namespace(self):
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return f"{self._target.name}.$cmd.aggregate"
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@property
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def _database(self):
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return self._target
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def _cursor_collection(self, cursor):
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"""The Collection used for the aggregate command cursor."""
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# Collection level aggregate may not always return the "ns" field
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# according to our MockupDB tests. Let's handle that case for db level
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# aggregate too by defaulting to the <db>.$cmd.aggregate namespace.
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_, collname = cursor.get("ns", self._cursor_namespace).split(".", 1)
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return self._database[collname]
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