Implementing Write Concern

Added write_options dict to save, update, update_one and get_or_create.
Thanks to justquick for the initial ticket and code.

Refs #132

mongoengine/document.py

@@ -40,44 +40,54 @@ class Document(BaseDocument):
     presence of `_cls` and `_types`, set :attr:`allow_inheritance` to
     ``False`` in the :attr:`meta` dictionary.
 
-    A :class:`~mongoengine.Document` may use a **Capped Collection** by 
+    A :class:`~mongoengine.Document` may use a **Capped Collection** by
     specifying :attr:`max_documents` and :attr:`max_size` in the :attr:`meta`
     dictionary. :attr:`max_documents` is the maximum number of documents that
-    is allowed to be stored in the collection, and :attr:`max_size` is the 
-    maximum size of the collection in bytes. If :attr:`max_size` is not 
-    specified and :attr:`max_documents` is, :attr:`max_size` defaults to 
+    is allowed to be stored in the collection, and :attr:`max_size` is the
+    maximum size of the collection in bytes. If :attr:`max_size` is not
+    specified and :attr:`max_documents` is, :attr:`max_size` defaults to
     10000000 bytes (10MB).
 
     Indexes may be created by specifying :attr:`indexes` in the :attr:`meta`
-    dictionary. The value should be a list of field names or tuples of field 
+    dictionary. The value should be a list of field names or tuples of field
     names. Index direction may be specified by prefixing the field names with
     a **+** or **-** sign.
     """
 
     __metaclass__ = TopLevelDocumentMetaclass
 
-    def save(self, safe=True, force_insert=False, validate=True):
+    def save(self, safe=True, force_insert=False, validate=True, write_options=None):
         """Save the :class:`~mongoengine.Document` to the database. If the
         document already exists, it will be updated, otherwise it will be
         created.
 
-        If ``safe=True`` and the operation is unsuccessful, an 
+        If ``safe=True`` and the operation is unsuccessful, an
         :class:`~mongoengine.OperationError` will be raised.
 
         :param safe: check if the operation succeeded before returning
-        :param force_insert: only try to create a new document, don't allow 
+        :param force_insert: only try to create a new document, don't allow
             updates of existing documents
         :param validate: validates the document; set to ``False`` to skip.
+        :param write_options: Extra keyword arguments are passed down to
+                :meth:`~pymongo.collection.Collection.save` OR
+                :meth:`~pymongo.collection.Collection.insert`
+                which will be used as options for the resultant ``getLastError`` command.
+                For example, ``save(..., w=2, fsync=True)`` will wait until at least two servers
+                have recorded the write and will force an fsync on each server being written to.
         """
         if validate:
             self.validate()
+
+        if not write_options:
+            write_options = {}
+
         doc = self.to_mongo()
         try:
             collection = self.__class__.objects._collection
             if force_insert:
-                object_id = collection.insert(doc, safe=safe)
+                object_id = collection.insert(doc, safe=safe, **write_options)
             else:
-                object_id = collection.save(doc, safe=safe)
+                object_id = collection.save(doc, safe=safe, **write_options)
         except pymongo.errors.OperationFailure, err:
             message = 'Could not save document (%s)'
             if u'duplicate key' in unicode(err):
@@ -131,9 +141,9 @@ class MapReduceDocument(object):
     """A document returned from a map/reduce query.
 
     :param collection: An instance of :class:`~pymongo.Collection`
-    :param key: Document/result key, often an instance of 
-                :class:`~pymongo.objectid.ObjectId`. If supplied as 
-                an ``ObjectId`` found in the given ``collection``, 
+    :param key: Document/result key, often an instance of
+                :class:`~pymongo.objectid.ObjectId`. If supplied as
+                an ``ObjectId`` found in the given ``collection``,
                 the object can be accessed via the ``object`` property.
     :param value: The result(s) for this key.
 
@@ -148,7 +158,7 @@ class MapReduceDocument(object):
 
     @property
     def object(self):
-        """Lazy-load the object referenced by ``self.key``. ``self.key`` 
+        """Lazy-load the object referenced by ``self.key``. ``self.key``
         should be the ``primary_key``.
         """
         id_field = self._document()._meta['id_field']