# Copyright 2019-present MongoDB, Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); you # may not use this file except in compliance with the License. You # may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or # implied. See the License for the specific language governing # permissions and limitations under the License. """Perform aggregation operations on a collection or database.""" from bson.son import SON from pymongo import common from pymongo.collation import validate_collation_or_none from pymongo.errors import ConfigurationError from pymongo.read_preferences import ReadPreference, _AggWritePref class _AggregationCommand(object): """The internal abstract base class for aggregation cursors. Should not be called directly by application developers. Use :meth:`pymongo.collection.Collection.aggregate`, or :meth:`pymongo.database.Database.aggregate` instead. """ def __init__( self, target, cursor_class, pipeline, options, explicit_session, let=None, user_fields=None, result_processor=None, comment=None, ): if "explain" in options: raise ConfigurationError( "The explain option is not supported. Use Database.command instead." ) self._target = target pipeline = common.validate_list("pipeline", pipeline) self._pipeline = pipeline self._performs_write = False if pipeline and ("$out" in pipeline[-1] or "$merge" in pipeline[-1]): self._performs_write = True common.validate_is_mapping("options", options) if let is not None: common.validate_is_mapping("let", let) options["let"] = let if comment is not None: options["comment"] = comment self._options = options # This is the batchSize that will be used for setting the initial # batchSize for the cursor, as well as the subsequent getMores. self._batch_size = common.validate_non_negative_integer_or_none( "batchSize", self._options.pop("batchSize", None) ) # If the cursor option is already specified, avoid overriding it. self._options.setdefault("cursor", {}) # If the pipeline performs a write, we ignore the initial batchSize # since the server doesn't return results in this case. if self._batch_size is not None and not self._performs_write: self._options["cursor"]["batchSize"] = self._batch_size self._cursor_class = cursor_class self._explicit_session = explicit_session self._user_fields = user_fields self._result_processor = result_processor self._collation = validate_collation_or_none(options.pop("collation", None)) self._max_await_time_ms = options.pop("maxAwaitTimeMS", None) self._write_preference = None @property def _aggregation_target(self): """The argument to pass to the aggregate command.""" raise NotImplementedError @property def _cursor_namespace(self): """The namespace in which the aggregate command is run.""" raise NotImplementedError def _cursor_collection(self, cursor_doc): """The Collection used for the aggregate command cursor.""" raise NotImplementedError @property def _database(self): """The database against which the aggregation command is run.""" raise NotImplementedError def get_read_preference(self, session): if self._write_preference: return self._write_preference pref = self._target._read_preference_for(session) if self._performs_write and pref != ReadPreference.PRIMARY: self._write_preference = pref = _AggWritePref(pref) return pref def get_cursor(self, session, server, sock_info, read_preference): # Serialize command. cmd = SON([("aggregate", self._aggregation_target), ("pipeline", self._pipeline)]) cmd.update(self._options) # Apply this target's read concern if: # readConcern has not been specified as a kwarg and either # - server version is >= 4.2 or # - server version is >= 3.2 and pipeline doesn't use $out if ("readConcern" not in cmd) and ( not self._performs_write or (sock_info.max_wire_version >= 8) ): read_concern = self._target.read_concern else: read_concern = None # Apply this target's write concern if: # writeConcern has not been specified as a kwarg and pipeline doesn't # perform a write operation if "writeConcern" not in cmd and self._performs_write: write_concern = self._target._write_concern_for(session) else: write_concern = None # Run command. result = sock_info.command( self._database.name, cmd, read_preference, self._target.codec_options, parse_write_concern_error=True, read_concern=read_concern, write_concern=write_concern, collation=self._collation, session=session, client=self._database.client, user_fields=self._user_fields, ) if self._result_processor: self._result_processor(result, sock_info) # Extract cursor from result or mock/fake one if necessary. if "cursor" in result: cursor = result["cursor"] else: # Unacknowledged $out/$merge write. Fake a cursor. cursor = { "id": 0, "firstBatch": result.get("result", []), "ns": self._cursor_namespace, } # Create and return cursor instance. cmd_cursor = self._cursor_class( self._cursor_collection(cursor), cursor, sock_info.address, batch_size=self._batch_size or 0, max_await_time_ms=self._max_await_time_ms, session=session, explicit_session=self._explicit_session, comment=self._options.get("comment"), ) cmd_cursor._maybe_pin_connection(sock_info) return cmd_cursor class _CollectionAggregationCommand(_AggregationCommand): @property def _aggregation_target(self): return self._target.name @property def _cursor_namespace(self): return self._target.full_name def _cursor_collection(self, cursor): """The Collection used for the aggregate command cursor.""" return self._target @property def _database(self): return self._target.database class _CollectionRawAggregationCommand(_CollectionAggregationCommand): def __init__(self, *args, **kwargs): super(_CollectionRawAggregationCommand, self).__init__(*args, **kwargs) # For raw-batches, we set the initial batchSize for the cursor to 0. if not self._performs_write: self._options["cursor"]["batchSize"] = 0 class _DatabaseAggregationCommand(_AggregationCommand): @property def _aggregation_target(self): return 1 @property def _cursor_namespace(self): return "%s.$cmd.aggregate" % (self._target.name,) @property def _database(self): return self._target def _cursor_collection(self, cursor): """The Collection used for the aggregate command cursor.""" # Collection level aggregate may not always return the "ns" field # according to our MockupDB tests. Let's handle that case for db level # aggregate too by defaulting to the .$cmd.aggregate namespace. _, collname = cursor.get("ns", self._cursor_namespace).split(".", 1) return self._database[collname]