text: # Copyright 2009-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.
  
  """Database level operations."""
  
  import warnings
  
  from bson.code import Code
  from bson.codec_options import DEFAULT_CODEC_OPTIONS
  from bson.dbref import DBRef
  from bson.py3compat import iteritems, string_type, _unicode
  from bson.son import SON
  from pymongo import auth, common
  from pymongo.collection import Collection
  from pymongo.command_cursor import CommandCursor
  from pymongo.errors import (CollectionInvalid,
                              ConfigurationError,
                              InvalidName,
                              OperationFailure)
  from pymongo.message import _first_batch
  from pymongo.read_preferences import ReadPreference
  from pymongo.son_manipulator import SONManipulator
  from pymongo.write_concern import WriteConcern
  
  
  _INDEX_REGEX = {"name": {"$regex": "^(?!.*\$)"}}
  _SYSTEM_FILTER = {"filter": {"name": {"$regex": "^(?!system\.)"}}}
  
  
  def _check_name(name):
      """Check if a database name is valid.
      """
      if not name:
          raise InvalidName("database name cannot be the empty string")
  
      for invalid_char in [' ', '.', '$', '/', '\\', '\x00', '"']:
          if invalid_char in name:
              raise InvalidName("database names cannot contain the "
                                "character %r" % invalid_char)
  
  
  class Database(common.BaseObject):
      """A Mongo database.
      """
  
      def __init__(self, client, name, codec_options=None, read_preference=None,
                   write_concern=None, read_concern=None):
          """Get a database by client and name.
  
          Raises :class:`TypeError` if `name` is not an instance of
          :class:`basestring` (:class:`str` in python 3). Raises
          :class:`~pymongo.errors.InvalidName` if `name` is not a valid
          database name.
  
          :Parameters:
            - `client`: A :class:`~pymongo.mongo_client.MongoClient` instance.
            - `name`: The database name.
            - `codec_options` (optional): An instance of
              :class:`~bson.codec_options.CodecOptions`. If ``None`` (the
              default) client.codec_options is used.
            - `read_preference` (optional): The read preference to use. If
              ``None`` (the default) client.read_preference is used.
            - `write_concern` (optional): An instance of
              :class:`~pymongo.write_concern.WriteConcern`. If ``None`` (the
              default) client.write_concern is used.
            - `read_concern` (optional): An instance of
              :class:`~pymongo.read_concern.ReadConcern`. If ``None`` (the
              default) client.read_concern is used.
  
          .. mongodoc:: databases
  
          .. versionchanged:: 3.2
             Added the read_concern option.
  
          .. versionchanged:: 3.0
             Added the codec_options, read_preference, and write_concern options.
             :class:`~pymongo.database.Database` no longer returns an instance
             of :class:`~pymongo.collection.Collection` for attribute names
             with leading underscores. You must use dict-style lookups instead::
  
                 db['__my_collection__']
  
             Not:
  
                 db.__my_collection__
          """
          super(Database, self).__init__(
              codec_options or client.codec_options,
              read_preference or client.read_preference,
              write_concern or client.write_concern,
              read_concern or client.read_concern)
  
          if not isinstance(name, string_type):
              raise TypeError("name must be an instance "
                              "of %s" % (string_type.__name__,))
  
          if name != '$external':
              _check_name(name)
  
          self.__name = _unicode(name)
          self.__client = client
  
          self.__incoming_manipulators = []
          self.__incoming_copying_manipulators = []
          self.__outgoing_manipulators = []
          self.__outgoing_copying_manipulators = []
  
      def add_son_manipulator(self, manipulator):
          """Add a new son manipulator to this database.
  
          **DEPRECATED** - `add_son_manipulator` is deprecated.
  
          .. versionchanged:: 3.0
            Deprecated add_son_manipulator.
          """
          warnings.warn("add_son_manipulator is deprecated",
                        DeprecationWarning, stacklevel=2)
          base = SONManipulator()
          def method_overwritten(instance, method):
              """Test if this method has been overridden."""
              return (getattr(
                  instance, method).__func__ != getattr(base, method).__func__)
  
          if manipulator.will_copy():
              if method_overwritten(manipulator, "transform_incoming"):
                  self.__incoming_copying_manipulators.insert(0, manipulator)
              if method_overwritten(manipulator, "transform_outgoing"):
                  self.__outgoing_copying_manipulators.insert(0, manipulator)
          else:
              if method_overwritten(manipulator, "transform_incoming"):
                  self.__incoming_manipulators.insert(0, manipulator)
              if method_overwritten(manipulator, "transform_outgoing"):
                  self.__outgoing_manipulators.insert(0, manipulator)
  
      @property
      def system_js(self):
          """**DEPRECATED**: :class:`SystemJS` helper for this :class:`Database`.
  
          See the documentation for :class:`SystemJS` for more details.
          """
          return SystemJS(self)
  
      @property
      def client(self):
          """The client instance for this :class:`Database`."""
          return self.__client
  
      @property
      def name(self):
          """The name of this :class:`Database`."""
          return self.__name
  
      @property
      def incoming_manipulators(self):
          """**DEPRECATED**: All incoming SON manipulators.
  
          .. versionchanged:: 3.5
            Deprecated.
  
          .. versionadded:: 2.0
          """
          warnings.warn("Database.incoming_manipulators() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          return [manipulator.__class__.__name__
                  for manipulator in self.__incoming_manipulators]
  
      @property
      def incoming_copying_manipulators(self):
          """**DEPRECATED**: All incoming SON copying manipulators.
  
          .. versionchanged:: 3.5
            Deprecated.
  
          .. versionadded:: 2.0
          """
          warnings.warn("Database.incoming_copying_manipulators() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          return [manipulator.__class__.__name__
                  for manipulator in self.__incoming_copying_manipulators]
  
      @property
      def outgoing_manipulators(self):
          """**DEPRECATED**: All outgoing SON manipulators.
  
          .. versionchanged:: 3.5
            Deprecated.
  
          .. versionadded:: 2.0
          """
          warnings.warn("Database.outgoing_manipulators() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          return [manipulator.__class__.__name__
                  for manipulator in self.__outgoing_manipulators]
  
      @property
      def outgoing_copying_manipulators(self):
          """**DEPRECATED**: All outgoing SON copying manipulators.
  
          .. versionchanged:: 3.5
            Deprecated.
  
          .. versionadded:: 2.0
          """
          warnings.warn("Database.outgoing_copying_manipulators() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          return [manipulator.__class__.__name__
                  for manipulator in self.__outgoing_copying_manipulators]
  
      def __eq__(self, other):
          if isinstance(other, Database):
              return (self.__client == other.client and
                      self.__name == other.name)
          return NotImplemented
  
      def __ne__(self, other):
          return not self == other
  
      def __repr__(self):
          return "Database(%r, %r)" % (self.__client, self.__name)
  
      def __getattr__(self, name):
          """Get a collection of this database by name.
  
          Raises InvalidName if an invalid collection name is used.
  
          :Parameters:
            - `name`: the name of the collection to get
          """
          if name.startswith('_'):
              raise AttributeError(
                  "Database has no attribute %r. To access the %s"
                  " collection, use database[%r]." % (name, name, name))
          return self.__getitem__(name)
  
      def __getitem__(self, name):
          """Get a collection of this database by name.
  
          Raises InvalidName if an invalid collection name is used.
  
          :Parameters:
            - `name`: the name of the collection to get
          """
          return Collection(self, name)
  
      def get_collection(self, name, codec_options=None, read_preference=None,
                         write_concern=None, read_concern=None):
          """Get a :class:`~pymongo.collection.Collection` with the given name
          and options.
  
          Useful for creating a :class:`~pymongo.collection.Collection` with
          different codec options, read preference, and/or write concern from
          this :class:`Database`.
  
            >>> db.read_preference
            Primary()
            >>> coll1 = db.test
            >>> coll1.read_preference
            Primary()
            >>> from pymongo import ReadPreference
            >>> coll2 = db.get_collection(
            ...     'test', read_preference=ReadPreference.SECONDARY)
            >>> coll2.read_preference
            Secondary(tag_sets=None)
  
          :Parameters:
            - `name`: The name of the collection - a string.
            - `codec_options` (optional): An instance of
              :class:`~bson.codec_options.CodecOptions`. If ``None`` (the
              default) the :attr:`codec_options` of this :class:`Database` is
              used.
            - `read_preference` (optional): The read preference to use. If
              ``None`` (the default) the :attr:`read_preference` of this
              :class:`Database` is used. See :mod:`~pymongo.read_preferences`
              for options.
            - `write_concern` (optional): An instance of
              :class:`~pymongo.write_concern.WriteConcern`. If ``None`` (the
              default) the :attr:`write_concern` of this :class:`Database` is
              used.
            - `read_concern` (optional): An instance of
              :class:`~pymongo.read_concern.ReadConcern`. If ``None`` (the
              default) the :attr:`read_concern` of this :class:`Database` is
              used.
          """
          return Collection(
              self, name, False, codec_options, read_preference,
              write_concern, read_concern)
  
      def _collection_default_options(self, name, **kargs):
          """Get a Collection instance with the default settings."""
          wc = (self.write_concern
                if self.write_concern.acknowledged else WriteConcern())
          return self.get_collection(
              name, codec_options=DEFAULT_CODEC_OPTIONS,
              read_preference=ReadPreference.PRIMARY,
              write_concern=wc)
  
      def create_collection(self, name, codec_options=None,
                            read_preference=None, write_concern=None,
                            read_concern=None, session=None, **kwargs):
          """Create a new :class:`~pymongo.collection.Collection` in this
          database.
  
          Normally collection creation is automatic. This method should
          only be used to specify options on
          creation. :class:`~pymongo.errors.CollectionInvalid` will be
          raised if the collection already exists.
  
          Options should be passed as keyword arguments to this method. Supported
          options vary with MongoDB release. Some examples include:
  
            - "size": desired initial size for the collection (in
              bytes). For capped collections this size is the max
              size of the collection.
            - "capped": if True, this is a capped collection
            - "max": maximum number of objects if capped (optional)
  
          See the MongoDB documentation for a full list of supported options by
          server version.
  
          :Parameters:
            - `name`: the name of the collection to create
            - `codec_options` (optional): An instance of
              :class:`~bson.codec_options.CodecOptions`. If ``None`` (the
              default) the :attr:`codec_options` of this :class:`Database` is
              used.
            - `read_preference` (optional): The read preference to use. If
              ``None`` (the default) the :attr:`read_preference` of this
              :class:`Database` is used.
            - `write_concern` (optional): An instance of
              :class:`~pymongo.write_concern.WriteConcern`. If ``None`` (the
              default) the :attr:`write_concern` of this :class:`Database` is
              used.
            - `read_concern` (optional): An instance of
              :class:`~pymongo.read_concern.ReadConcern`. If ``None`` (the
              default) the :attr:`read_concern` of this :class:`Database` is
              used.
            - `collation` (optional): An instance of
              :class:`~pymongo.collation.Collation`.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
            - `**kwargs` (optional): additional keyword arguments will
              be passed as options for the create collection command
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. versionchanged:: 3.4
             Added the collation option.
  
          .. versionchanged:: 3.0
             Added the codec_options, read_preference, and write_concern options.
  
          .. versionchanged:: 2.2
             Removed deprecated argument: options
          """
          with self.__client._tmp_session(session) as s:
              if name in self.collection_names(session=s):
                  raise CollectionInvalid("collection %s already exists" % name)
  
              return Collection(self, name, True, codec_options,
                                read_preference, write_concern,
                                read_concern, session=s, **kwargs)
  
      def _apply_incoming_manipulators(self, son, collection):
          """Apply incoming manipulators to `son`."""
          for manipulator in self.__incoming_manipulators:
              son = manipulator.transform_incoming(son, collection)
          return son
  
      def _apply_incoming_copying_manipulators(self, son, collection):
          """Apply incoming copying manipulators to `son`."""
          for manipulator in self.__incoming_copying_manipulators:
              son = manipulator.transform_incoming(son, collection)
          return son
  
      def _fix_incoming(self, son, collection):
          """Apply manipulators to an incoming SON object before it gets stored.
  
          :Parameters:
            - `son`: the son object going into the database
            - `collection`: the collection the son object is being saved in
          """
          son = self._apply_incoming_manipulators(son, collection)
          son = self._apply_incoming_copying_manipulators(son, collection)
          return son
  
      def _fix_outgoing(self, son, collection):
          """Apply manipulators to a SON object as it comes out of the database.
  
          :Parameters:
            - `son`: the son object coming out of the database
            - `collection`: the collection the son object was saved in
          """
          for manipulator in reversed(self.__outgoing_manipulators):
              son = manipulator.transform_outgoing(son, collection)
          for manipulator in reversed(self.__outgoing_copying_manipulators):
              son = manipulator.transform_outgoing(son, collection)
          return son
  
      def _command(self, sock_info, command, slave_ok=False, value=1, check=True,
                   allowable_errors=None, read_preference=ReadPreference.PRIMARY,
                   codec_options=DEFAULT_CODEC_OPTIONS,
                   write_concern=None,
                   parse_write_concern_error=False, session=None, **kwargs):
          """Internal command helper."""
          if isinstance(command, string_type):
              command = SON([(command, value)])
  
          if sock_info.max_wire_version >= 5 and write_concern:
              command['writeConcern'] = write_concern.document
  
          command.update(kwargs)
          with self.__client._tmp_session(session) as s:
              return sock_info.command(
                  self.__name,
                  command,
                  slave_ok,
                  read_preference,
                  codec_options,
                  check,
                  allowable_errors,
                  parse_write_concern_error=parse_write_concern_error,
                  session=s,
                  client=self.__client)
  
      def command(self, command, value=1, check=True,
                  allowable_errors=None, read_preference=ReadPreference.PRIMARY,
                  codec_options=DEFAULT_CODEC_OPTIONS, session=None, **kwargs):
          """Issue a MongoDB command.
  
          Send command `command` to the database and return the
          response. If `command` is an instance of :class:`basestring`
          (:class:`str` in python 3) then the command {`command`: `value`}
          will be sent. Otherwise, `command` must be an instance of
          :class:`dict` and will be sent as is.
  
          Any additional keyword arguments will be added to the final
          command document before it is sent.
  
          For example, a command like ``{buildinfo: 1}`` can be sent
          using:
  
          >>> db.command("buildinfo")
  
          For a command where the value matters, like ``{collstats:
          collection_name}`` we can do:
  
          >>> db.command("collstats", collection_name)
  
          For commands that take additional arguments we can use
          kwargs. So ``{filemd5: object_id, root: file_root}`` becomes:
  
          >>> db.command("filemd5", object_id, root=file_root)
  
          :Parameters:
            - `command`: document representing the command to be issued,
              or the name of the command (for simple commands only).
  
              .. note:: the order of keys in the `command` document is
                 significant (the "verb" must come first), so commands
                 which require multiple keys (e.g. `findandmodify`)
                 should use an instance of :class:`~bson.son.SON` or
                 a string and kwargs instead of a Python `dict`.
  
            - `value` (optional): value to use for the command verb when
              `command` is passed as a string
            - `check` (optional): check the response for errors, raising
              :class:`~pymongo.errors.OperationFailure` if there are any
            - `allowable_errors`: if `check` is ``True``, error messages
              in this list will be ignored by error-checking
            - `read_preference`: The read preference for this operation.
              See :mod:`~pymongo.read_preferences` for options.
            - `codec_options`: A :class:`~bson.codec_options.CodecOptions`
              instance.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
            - `**kwargs` (optional): additional keyword arguments will
              be added to the command document before it is sent
  
          .. note:: :meth:`command` does **not** obey :attr:`read_preference`
             or :attr:`codec_options`. You must use the `read_preference` and
             `codec_options` parameters instead.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. versionchanged:: 3.0
             Removed the `as_class`, `fields`, `uuid_subtype`, `tag_sets`,
             and `secondary_acceptable_latency_ms` option.
             Removed `compile_re` option: PyMongo now always represents BSON
             regular expressions as :class:`~bson.regex.Regex` objects. Use
             :meth:`~bson.regex.Regex.try_compile` to attempt to convert from a
             BSON regular expression to a Python regular expression object.
             Added the `codec_options` parameter.
  
          .. versionchanged:: 2.7
             Added `compile_re` option. If set to False, PyMongo represented BSON
             regular expressions as :class:`~bson.regex.Regex` objects instead of
             attempting to compile BSON regular expressions as Python native
             regular expressions, thus preventing errors for some incompatible
             patterns, see `PYTHON-500`_.
  
          .. versionchanged:: 2.3
             Added `tag_sets` and `secondary_acceptable_latency_ms` options.
          .. versionchanged:: 2.2
             Added support for `as_class` - the class you want to use for
             the resulting documents
  
          .. _PYTHON-500: https://jira.mongodb.org/browse/PYTHON-500
  
          .. mongodoc:: commands
          """
          client = self.__client
          with client._socket_for_reads(read_preference) as (sock_info, slave_ok):
              return self._command(sock_info, command, slave_ok, value,
                                   check, allowable_errors, read_preference,
                                   codec_options, session=session, **kwargs)
  
      def _list_collections(self, sock_info, slave_okay, session=None, **kwargs):
          """Internal listCollections helper."""
  
          coll = self.get_collection(
              "$cmd", read_preference=ReadPreference.PRIMARY)
          if sock_info.max_wire_version > 2:
              cmd = SON([("listCollections", 1),
                         ("cursor", {})])
              cmd.update(kwargs)
              with self.__client._tmp_session(
                      session, close=False) as tmp_session:
                  cursor = self._command(
                      sock_info, cmd, slave_okay, session=tmp_session)["cursor"]
                  return CommandCursor(
                      coll,
                      cursor,
                      sock_info.address,
                      session=tmp_session,
                      explicit_session=session is not None)
          else:
              match = _INDEX_REGEX
              if "filter" in kwargs:
                  match = {"$and": [_INDEX_REGEX, kwargs["filter"]]}
              dblen = len(self.name.encode("utf8") + b".")
              pipeline = [
                  {"$project": {"name": {"$substr": ["$name", dblen, -1]},
                                "options": 1}},
                  {"$match": match}
              ]
              cmd = SON([("aggregate", "system.namespaces"),
                         ("pipeline", pipeline),
                         ("cursor", kwargs.get("cursor", {}))])
              cursor = self._command(sock_info, cmd, slave_okay)["cursor"]
              return CommandCursor(coll, cursor, sock_info.address)
  
      def list_collections(self, session=None, **kwargs):
          """Get a cursor over the collectons of this database.
  
          :Parameters:
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
            - `**kwargs` (optional): Optional parameters of the
              `listCollections command
              <https://docs.mongodb.com/manual/reference/command/listCollections/>`_
              can be passed as keyword arguments to this method. The supported
              options differ by server version.
  
          :Returns:
            An instance of :class:`~pymongo.command_cursor.CommandCursor`.
  
          .. versionadded:: 3.6
          """
          with self.__client._socket_for_reads(
                  ReadPreference.PRIMARY) as (sock_info, slave_okay):
              return self._list_collections(
                  sock_info, slave_okay, session=session, **kwargs)
  
      def list_collection_names(self, session=None):
          """Get a list of all the collection names in this database.
  
          :Parameters:
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionadded:: 3.6
          """
          return [result["name"]
                  for result in self.list_collections(session=session)]
  
      def collection_names(self, include_system_collections=True,
                           session=None):
          """Get a list of all the collection names in this database.
  
          :Parameters:
            - `include_system_collections` (optional): if ``False`` list
              will not include system collections (e.g ``system.indexes``)
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          kws = {} if include_system_collections else _SYSTEM_FILTER
          return [result["name"]
                  for result in self.list_collections(session=session, **kws)]
  
      def drop_collection(self, name_or_collection, session=None):
          """Drop a collection.
  
          :Parameters:
            - `name_or_collection`: the name of a collection to drop or the
              collection object itself
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. note:: The :attr:`~pymongo.database.Database.write_concern` of
             this database is automatically applied to this operation when using
             MongoDB >= 3.4.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. versionchanged:: 3.4
             Apply this database's write concern automatically to this operation
             when connected to MongoDB >= 3.4.
  
          """
          name = name_or_collection
          if isinstance(name, Collection):
              name = name.name
  
          if not isinstance(name, string_type):
              raise TypeError("name_or_collection must be an "
                              "instance of %s" % (string_type.__name__,))
  
          self.__client._purge_index(self.__name, name)
  
          with self.__client._socket_for_reads(
                  ReadPreference.PRIMARY) as (sock_info, slave_ok):
              return self._command(
                  sock_info, 'drop', slave_ok, _unicode(name),
                  allowable_errors=['ns not found'],
                  write_concern=self.write_concern,
                  parse_write_concern_error=True,
                  session=session)
  
      def validate_collection(self, name_or_collection,
                              scandata=False, full=False, session=None):
          """Validate a collection.
  
          Returns a dict of validation info. Raises CollectionInvalid if
          validation fails.
  
          :Parameters:
            - `name_or_collection`: A Collection object or the name of a
              collection to validate.
            - `scandata`: Do extra checks beyond checking the overall
              structure of the collection.
            - `full`: Have the server do a more thorough scan of the
              collection. Use with `scandata` for a thorough scan
              of the structure of the collection and the individual
              documents.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          name = name_or_collection
          if isinstance(name, Collection):
              name = name.name
  
          if not isinstance(name, string_type):
              raise TypeError("name_or_collection must be an instance of "
                              "%s or Collection" % (string_type.__name__,))
  
          result = self.command("validate", _unicode(name),
                                scandata=scandata, full=full, session=session)
  
          valid = True
          # Pre 1.9 results
          if "result" in result:
              info = result["result"]
              if info.find("exception") != -1 or info.find("corrupt") != -1:
                  raise CollectionInvalid("%s invalid: %s" % (name, info))
          # Sharded results
          elif "raw" in result:
              for _, res in iteritems(result["raw"]):
                  if "result" in res:
                      info = res["result"]
                      if (info.find("exception") != -1 or
                              info.find("corrupt") != -1):
                          raise CollectionInvalid("%s invalid: "
                                                  "%s" % (name, info))
                  elif not res.get("valid", False):
                      valid = False
                      break
          # Post 1.9 non-sharded results.
          elif not result.get("valid", False):
              valid = False
  
          if not valid:
              raise CollectionInvalid("%s invalid: %r" % (name, result))
  
          return result
  
      def current_op(self, include_all=False, session=None):
          """Get information on operations currently running.
  
          :Parameters:
            - `include_all` (optional): if ``True`` also list currently
              idle operations in the result
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          cmd = SON([("currentOp", 1), ("$all", include_all)])
          with self.__client._socket_for_writes() as sock_info:
              if sock_info.max_wire_version >= 4:
                  with self.__client._tmp_session(session) as s:
                      return sock_info.command("admin", cmd, session=s,
                                               client=self.__client)
              else:
                  spec = {"$all": True} if include_all else {}
                  return _first_batch(sock_info, "admin", "$cmd.sys.inprog",
                                      spec, -1, True, self.codec_options,
                                      ReadPreference.PRIMARY, cmd,
                                      self.client._event_listeners)
  
      def profiling_level(self, session=None):
          """Get the database's current profiling level.
  
          Returns one of (:data:`~pymongo.OFF`,
          :data:`~pymongo.SLOW_ONLY`, :data:`~pymongo.ALL`).
  
          :Parameters:
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. mongodoc:: profiling
          """
          result = self.command("profile", -1, session=session)
  
          assert result["was"] >= 0 and result["was"] <= 2
          return result["was"]
  
      def set_profiling_level(self, level, slow_ms=None, session=None):
          """Set the database's profiling level.
  
          :Parameters:
            - `level`: Specifies a profiling level, see list of possible values
              below.
            - `slow_ms`: Optionally modify the threshold for the profile to
              consider a query or operation.  Even if the profiler is off queries
              slower than the `slow_ms` level will get written to the logs.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          Possible `level` values:
  
          +----------------------------+------------------------------------+
          | Level                      | Setting                            |
          +============================+====================================+
          | :data:`~pymongo.OFF`       | Off. No profiling.                 |
          +----------------------------+------------------------------------+
          | :data:`~pymongo.SLOW_ONLY` | On. Only includes slow operations. |
          +----------------------------+------------------------------------+
          | :data:`~pymongo.ALL`       | On. Includes all operations.       |
          +----------------------------+------------------------------------+
  
          Raises :class:`ValueError` if level is not one of
          (:data:`~pymongo.OFF`, :data:`~pymongo.SLOW_ONLY`,
          :data:`~pymongo.ALL`).
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. mongodoc:: profiling
          """
          if not isinstance(level, int) or level < 0 or level > 2:
              raise ValueError("level must be one of (OFF, SLOW_ONLY, ALL)")
  
          if slow_ms is not None and not isinstance(slow_ms, int):
              raise TypeError("slow_ms must be an integer")
  
          if slow_ms is not None:
              self.command("profile", level, slowms=slow_ms, session=session)
          else:
              self.command("profile", level, session=session)
  
      def profiling_info(self, session=None):
          """Returns a list containing current profiling information.
  
          :Parameters:
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. mongodoc:: profiling
          """
          return list(self["system.profile"].find(session=session))
  
      def error(self):
          """**DEPRECATED**: Get the error if one occurred on the last operation.
  
          This method is obsolete: all MongoDB write operations (insert, update,
          remove, and so on) use the write concern ``w=1`` and report their
          errors by default.
  
          .. versionchanged:: 2.8
             Deprecated.
          """
          warnings.warn("Database.error() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          error = self.command("getlasterror")
          error_msg = error.get("err", "")
          if error_msg is None:
              return None
          if error_msg.startswith("not master"):
              # Reset primary server and request check, if another thread isn't
              # doing so already.
              primary = self.__client.primary
              if primary:
                  self.__client._reset_server_and_request_check(primary)
          return error
  
      def last_status(self):
          """**DEPRECATED**: Get status information from the last operation.
  
          This method is obsolete: all MongoDB write operations (insert, update,
          remove, and so on) use the write concern ``w=1`` and report their
          errors by default.
  
          Returns a SON object with status information.
  
          .. versionchanged:: 2.8
             Deprecated.
          """
          warnings.warn("last_status() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          return self.command("getlasterror")
  
      def previous_error(self):
          """**DEPRECATED**: Get the most recent error on this database.
  
          This method is obsolete: all MongoDB write operations (insert, update,
          remove, and so on) use the write concern ``w=1`` and report their
          errors by default.
  
          Only returns errors that have occurred since the last call to
          :meth:`reset_error_history`. Returns None if no such errors have
          occurred.
  
          .. versionchanged:: 2.8
             Deprecated.
          """
          warnings.warn("previous_error() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          error = self.command("getpreverror")
          if error.get("err", 0) is None:
              return None
          return error
  
      def reset_error_history(self):
          """**DEPRECATED**: Reset the error history of this database.
  
          This method is obsolete: all MongoDB write operations (insert, update,
          remove, and so on) use the write concern ``w=1`` and report their
          errors by default.
  
          Calls to :meth:`previous_error` will only return errors that have
          occurred since the most recent call to this method.
  
          .. versionchanged:: 2.8
             Deprecated.
          """
          warnings.warn("reset_error_history() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          self.command("reseterror")
  
      def __iter__(self):
          return self
  
      def __next__(self):
          raise TypeError("'Database' object is not iterable")
  
      next = __next__
  
      def _default_role(self, read_only):
          """Return the default user role for this database."""
          if self.name == "admin":
              if read_only:
                  return "readAnyDatabase"
              else:
                  return "root"
          else:
              if read_only:
                  return "read"
              else:
                  return "dbOwner"
  
      def _create_or_update_user(
              self, create, name, password, read_only, session=None, **kwargs):
          """Use a command to create (if create=True) or modify a user.
          """
          opts = {}
          if read_only or (create and "roles" not in kwargs):
              warnings.warn("Creating a user with the read_only option "
                            "or without roles is deprecated in MongoDB "
                            ">= 2.6", DeprecationWarning)
  
              opts["roles"] = [self._default_role(read_only)]
  
          elif read_only:
              warnings.warn("The read_only option is deprecated in MongoDB "
                            ">= 2.6, use 'roles' instead", DeprecationWarning)
  
          if password is not None:
              if "digestPassword" in kwargs:
                  raise ConfigurationError("The digestPassword option is not "
                                           "supported via add_user. Please use "
                                           "db.command('createUser', ...) "
                                           "instead for this option.")
              opts["pwd"] = password
  
          # Don't send {} as writeConcern.
          if self.write_concern.acknowledged and self.write_concern.document:
              opts["writeConcern"] = self.write_concern.document
          opts.update(kwargs)
  
          if create:
              command_name = "createUser"
          else:
              command_name = "updateUser"
  
          self.command(command_name, name, session=session, **opts)
  
      def add_user(self, name, password=None, read_only=None, session=None,
                   **kwargs):
          """**DEPRECATED**: Create user `name` with password `password`.
  
          Add a new user with permissions for this :class:`Database`.
  
          .. note:: Will change the password if user `name` already exists.
  
          .. note:: add_user is deprecated and will be removed in PyMongo
            4.0. Starting with MongoDB 2.6 user management is handled with four
            database commands, createUser_, usersInfo_, updateUser_, and
            dropUser_.
  
            To create a user::
  
              db.command("createUser", "admin", pwd="password", roles=["root"])
  
            To create a read-only user::
  
              db.command("createUser", "user", pwd="password", roles=["read"])
  
            To change a password::
  
              db.command("updateUser", "user", pwd="newpassword")
  
            Or change roles::
  
              db.command("updateUser", "user", roles=["readWrite"])
  
          .. _createUser: https://docs.mongodb.com/manual/reference/command/createUser/
          .. _usersInfo: https://docs.mongodb.com/manual/reference/command/usersInfo/
          .. _updateUser: https://docs.mongodb.com/manual/reference/command/updateUser/
          .. _dropUser: https://docs.mongodb.com/manual/reference/command/createUser/
  
          .. warning:: Never create or modify users over an insecure network without
            the use of TLS. See :doc:`/examples/tls` for more information.
  
          :Parameters:
            - `name`: the name of the user to create
            - `password` (optional): the password of the user to create. Can not
              be used with the ``userSource`` argument.
            - `read_only` (optional): if ``True`` the user will be read only
            - `**kwargs` (optional): optional fields for the user document
              (e.g. ``userSource``, ``otherDBRoles``, or ``roles``). See
              `<http://docs.mongodb.org/manual/reference/privilege-documents>`_
              for more information.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.7
             Added support for SCRAM-SHA-256 users with MongoDB 4.0 and later.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter. Deprecated add_user.
  
          .. versionchanged:: 2.5
             Added kwargs support for optional fields introduced in MongoDB 2.4
  
          .. versionchanged:: 2.2
             Added support for read only users
          """
          warnings.warn("add_user is deprecated and will be removed in PyMongo "
                        "4.0. Use db.command with createUser or updateUser "
                        "instead", DeprecationWarning, stacklevel=2)
          if not isinstance(name, string_type):
              raise TypeError("name must be an "
                              "instance of %s" % (string_type.__name__,))
          if password is not None:
              if not isinstance(password, string_type):
                  raise TypeError("password must be an "
                                  "instance of %s" % (string_type.__name__,))
              if len(password) == 0:
                  raise ValueError("password can't be empty")
          if read_only is not None:
              read_only = common.validate_boolean('read_only', read_only)
              if 'roles' in kwargs:
                  raise ConfigurationError("Can not use "
                                           "read_only and roles together")
  
          try:
              uinfo = self.command("usersInfo", name, session=session)
              # Create the user if not found in uinfo, otherwise update one.
              self._create_or_update_user(
                  (not uinfo["users"]), name, password, read_only,
                  session=session, **kwargs)
          except OperationFailure as exc:
              # Unauthorized. Attempt to create the user in case of
              # localhost exception.
              if exc.code == 13:
                  self._create_or_update_user(
                      True, name, password, read_only, session=session, **kwargs)
              else:
                  raise
  
      def remove_user(self, name, session=None):
          """**DEPRECATED**: Remove user `name` from this :class:`Database`.
  
          User `name` will no longer have permissions to access this
          :class:`Database`.
  
          .. note:: remove_user is deprecated and will be removed in PyMongo
            4.0. Use the dropUser command instead::
  
              db.command("dropUser", "user")
  
          :Parameters:
            - `name`: the name of the user to remove
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter. Deprecated remove_user.
          """
          warnings.warn("remove_user is deprecated and will be removed in "
                        "PyMongo 4.0. Use db.command with dropUser "
                        "instead", DeprecationWarning, stacklevel=2)
          cmd = SON([("dropUser", name)])
          # Don't send {} as writeConcern.
          if self.write_concern.acknowledged and self.write_concern.document:
              cmd["writeConcern"] = self.write_concern.document
          self.command(cmd, session=session)
  
      def authenticate(self, name=None, password=None,
                       source=None, mechanism='DEFAULT', **kwargs):
          """**DEPRECATED**: Authenticate to use this database.
  
          .. warning:: Starting in MongoDB 3.6, calling :meth:`authenticate`
            invalidates all existing cursors. It may also leave logical sessions
            open on the server for up to 30 minutes until they time out.
  
          Authentication lasts for the life of the underlying client
          instance, or until :meth:`logout` is called.
  
          Raises :class:`TypeError` if (required) `name`, (optional) `password`,
          or (optional) `source` is not an instance of :class:`basestring`
          (:class:`str` in python 3).
  
          .. note::
            - This method authenticates the current connection, and
              will also cause all new :class:`~socket.socket` connections
              in the underlying client instance to be authenticated automatically.
  
            - Authenticating more than once on the same database with different
              credentials is not supported. You must call :meth:`logout` before
              authenticating with new credentials.
  
            - When sharing a client instance between multiple threads, all
              threads will share the authentication. If you need different
              authentication profiles for different purposes you must use
              distinct client instances.
  
          :Parameters:
            - `name`: the name of the user to authenticate. Optional when
              `mechanism` is MONGODB-X509 and the MongoDB server version is
              >= 3.4.
            - `password` (optional): the password of the user to authenticate.
              Not used with GSSAPI or MONGODB-X509 authentication.
            - `source` (optional): the database to authenticate on. If not
              specified the current database is used.
            - `mechanism` (optional): See :data:`~pymongo.auth.MECHANISMS` for
              options. If no mechanism is specified, PyMongo automatically uses
              MONGODB-CR when connected to a pre-3.0 version of MongoDB,
              SCRAM-SHA-1 when connected to MongoDB 3.0 through 3.6, and
              negotiates the mechanism to use (SCRAM-SHA-1 or SCRAM-SHA-256) when
              connected to MongoDB 4.0+.
            - `authMechanismProperties` (optional): Used to specify
              authentication mechanism specific options. To specify the service
              name for GSSAPI authentication pass
              authMechanismProperties='SERVICE_NAME:<service name>'
  
          .. versionchanged:: 3.7
             Added support for SCRAM-SHA-256 with MongoDB 4.0 and later.
  
          .. versionchanged:: 3.5
             Deprecated. Authenticating multiple users conflicts with support for
             logical sessions in MongoDB 3.6. To authenticate as multiple users,
             create multiple instances of MongoClient.
  
          .. versionadded:: 2.8
             Use SCRAM-SHA-1 with MongoDB 3.0 and later.
  
          .. versionchanged:: 2.5
             Added the `source` and `mechanism` parameters. :meth:`authenticate`
             now raises a subclass of :class:`~pymongo.errors.PyMongoError` if
             authentication fails due to invalid credentials or configuration
             issues.
  
          .. mongodoc:: authenticate
          """
          if name is not None and not isinstance(name, string_type):
              raise TypeError("name must be an "
                              "instance of %s" % (string_type.__name__,))
          if password is not None and not isinstance(password, string_type):
              raise TypeError("password must be an "
                              "instance of %s" % (string_type.__name__,))
          if source is not None and not isinstance(source, string_type):
              raise TypeError("source must be an "
                              "instance of %s" % (string_type.__name__,))
          common.validate_auth_mechanism('mechanism', mechanism)
  
          validated_options = {}
          for option, value in iteritems(kwargs):
              normalized, val = common.validate_auth_option(option, value)
              validated_options[normalized] = val
  
          credentials = auth._build_credentials_tuple(
              mechanism,
              source,
              name,
              password,
              validated_options,
              self.name)
  
          self.client._cache_credentials(
              self.name,
              credentials,
              connect=True)
  
          return True
  
      def logout(self):
          """**DEPRECATED**: Deauthorize use of this database.
  
          .. warning:: Starting in MongoDB 3.6, calling :meth:`logout`
            invalidates all existing cursors. It may also leave logical sessions
            open on the server for up to 30 minutes until they time out.
          """
          warnings.warn("Database.logout() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          # Sockets will be deauthenticated as they are used.
          self.client._purge_credentials(self.name)
  
      def dereference(self, dbref, session=None, **kwargs):
          """Dereference a :class:`~bson.dbref.DBRef`, getting the
          document it points to.
  
          Raises :class:`TypeError` if `dbref` is not an instance of
          :class:`~bson.dbref.DBRef`. Returns a document, or ``None`` if
          the reference does not point to a valid document.  Raises
          :class:`ValueError` if `dbref` has a database specified that
          is different from the current database.
  
          :Parameters:
            - `dbref`: the reference
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`.
            - `**kwargs` (optional): any additional keyword arguments
              are the same as the arguments to
              :meth:`~pymongo.collection.Collection.find`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          if not isinstance(dbref, DBRef):
              raise TypeError("cannot dereference a %s" % type(dbref))
          if dbref.database is not None and dbref.database != self.__name:
              raise ValueError("trying to dereference a DBRef that points to "
                               "another database (%r not %r)" % (dbref.database,
                                                                 self.__name))
          return self[dbref.collection].find_one(
              {"_id": dbref.id}, session=session, **kwargs)
  
      def eval(self, code, *args):
          """**DEPRECATED**: Evaluate a JavaScript expression in MongoDB.
  
          :Parameters:
            - `code`: string representation of JavaScript code to be
              evaluated
            - `args` (optional): additional positional arguments are
              passed to the `code` being evaluated
  
          .. warning:: the eval command is deprecated in MongoDB 3.0 and
            will be removed in a future server version.
          """
          warnings.warn("Database.eval() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          if not isinstance(code, Code):
              code = Code(code)
  
          result = self.command("$eval", code, args=args)
          return result.get("retval", None)
  
      def __call__(self, *args, **kwargs):
          """This is only here so that some API misusages are easier to debug.
          """
          raise TypeError("'Database' object is not callable. If you meant to "
                          "call the '%s' method on a '%s' object it is "
                          "failing because no such method exists." % (
                              self.__name, self.__client.__class__.__name__))
  
  
  class SystemJS(object):
      """**DEPRECATED**: Helper class for dealing with stored JavaScript.
      """
  
      def __init__(self, database):
          """**DEPRECATED**: Get a system js helper for the database `database`.
  
          SystemJS will be removed in PyMongo 4.0.
          """
          warnings.warn("SystemJS is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          if not database.write_concern.acknowledged:
              database = database.client.get_database(
                  database.name, write_concern=WriteConcern())
          # can't just assign it since we've overridden __setattr__
          object.__setattr__(self, "_db", database)
  
      def __setattr__(self, name, code):
          self._db.system.js.replace_one(
              {"_id": name}, {"_id": name, "value": Code(code)}, True)
  
      def __setitem__(self, name, code):
          self.__setattr__(name, code)
  
      def __delattr__(self, name):
          self._db.system.js.delete_one({"_id": name})
  
      def __delitem__(self, name):
          self.__delattr__(name)
  
      def __getattr__(self, name):
          return lambda *args: self._db.eval(Code("function() { "
                                                  "return this[name].apply("
                                                  "this, arguments); }",
                                                  scope={'name': name}), *args)
  
      def __getitem__(self, name):
          return self.__getattr__(name)
  
      def list(self):
          """Get a list of the names of the functions stored in this database."""
          return [x["_id"] for x in self._db.system.js.find(projection=["_id"])]
  