Adds a map __merge update mode, to merge in map with the existing values

on the server.

cqlengine/query.py

@@ -681,9 +681,10 @@ class ModelQuerySet(AbstractQuerySet):
             if isinstance(col, Counter):
                 # TODO: implement counter updates
                 raise NotImplementedError
-            elif isinstance(col, (List, Set)):
+            elif isinstance(col, (List, Set, Map)):
                 if isinstance(col, List): klass = ListUpdateClause
                 elif isinstance(col, Set): klass = SetUpdateClause
+                elif isinstance(col, Map): klass = MapUpdateClause
                 else: raise RuntimeError
                 us.add_assignment_clause(klass(
                     col_name, col.to_database(val), operation=col_op))

cqlengine/statements.py

@@ -310,13 +310,16 @@ class ListUpdateClause(ContainerUpdateClause):
 class MapUpdateClause(ContainerUpdateClause):
     """ updates a map collection """
 
-    def __init__(self, field, value, previous=None, column=None):
-        super(MapUpdateClause, self).__init__(field, value, previous, column=column)
+    def __init__(self, field, value, operation=None, previous=None, column=None):
+        super(MapUpdateClause, self).__init__(field, value, operation, previous, column=column)
         self._updates = None
         self.previous = self.previous or {}
 
     def _analyze(self):
-        self._updates = sorted([k for k, v in self.value.items() if v != self.previous.get(k)]) or None
+        if self._operation == "merge":
+            self._updates = self.value.value
+        else:
+            self._updates = sorted([k for k, v in self.value.items() if v != self.previous.get(k)]) or None
         self._analyzed = True
 
     def get_context_size(self):
@@ -326,8 +329,7 @@ class MapUpdateClause(ContainerUpdateClause):
     def update_context(self, ctx):
         if not self._analyzed: self._analyze()
         ctx_id = self.context_id
-        for key in self._updates or []:
-            val = self.value.get(key)
+        for key, val in self._updates.items():
             ctx[str(ctx_id)] = self._column.key_col.to_database(key) if self._column else key
             ctx[str(ctx_id + 1)] = self._column.value_col.to_database(val) if self._column else val
             ctx_id += 2

cqlengine/tests/query/test_updates.py

@@ -15,6 +15,7 @@ class TestQueryUpdateModel(Model):
     text        = columns.Text(required=False, index=True)
     text_set    = columns.Set(columns.Text, required=False)
     text_list   = columns.List(columns.Text, required=False)
+    text_map    = columns.Map(columns.Text, columns.Text, required=False)
 
 class QueryUpdateTests(BaseCassEngTestCase):
 
@@ -183,3 +184,16 @@ class QueryUpdateTests(BaseCassEngTestCase):
                 text_list__prepend=['bar', 'baz'])
         obj = TestQueryUpdateModel.objects.get(partition=partition, cluster=cluster)
         self.assertEqual(obj.text_list, ["bar", "baz", "foo"])
+
+    def test_map_merge_updates(self):
+        """ Merge a dictionary into existing value """
+        partition = uuid4()
+        cluster = 1
+        TestQueryUpdateModel.objects.create(
+                partition=partition, cluster=cluster,
+                text_map={"foo": '1', "bar": '2'})
+        TestQueryUpdateModel.objects(
+                partition=partition, cluster=cluster).update(
+                text_map__merge={"bar": '3', "baz": '4'})
+        obj = TestQueryUpdateModel.objects.get(partition=partition, cluster=cluster)
+        self.assertEqual(obj.text_map, {"foo": '1', "bar": '3', "baz": '4'})