clear() method for IMongoContainer

src/mongopersist/zope/container.py

@@ -375,6 +375,10 @@ def find_one(self, spec_or_id=None, *args, **kwargs):
             return None
         return self._load_one(doc)
 
+    def clear(self):
+        for key in self.keys():
+            del self[key]
+
 
 class IdNamesMongoContainer(MongoContainer):
     """A container that uses the Mongo ObjectId as the name/key."""

src/mongopersist/zope/interfaces.py

@@ -114,3 +114,10 @@ def add(value, key=None):
         - in case _m_mapping_key is None: the object's OID
         - otherwise getattr(value, _m_mapping_key)
         """
+
+    def clear(self):
+        """Delete all items from this container.
+
+        Note, that this will not touch all items from the collection, but only
+        those, specified in _m_get_items_filter.
+        """