Improve group

aggify/aggify.py

@@ -116,12 +116,10 @@ def project(self, **kwargs: QueryParams) -> "Aggify":
     @last_out_stage_check
     def group(self, expression: Union[str, None] = "id") -> "Aggify":
         if expression:
-            check_fields_exist(self.base_model, [expression])
-        expression = (
-            get_db_field(self.base_model, expression, add_dollar_sign=True)
-            if expression
-            else None
-        )
+            try:
+                expression = "$" + self.get_field_name_recursively(expression)
+            except InvalidField:
+                pass
         self.pipelines.append({"$group": {"_id": expression}})
         return self
 

tests/test_aggify.py

@@ -613,3 +613,7 @@ def test_aggify_get_item_slice_negative_start(self):
         with pytest.raises(MongoIndexError):
             # noinspection PyUnusedLocal
             var = aggify.filter(name=1)[slice(-5, -1)]
+
+    def test_group_invalid_field(self):
+        thing = list(Aggify(BaseModel).group("invalid").annotate("name", "first", 2))
+        assert thing[0]["$group"] == {"_id": "invalid", "name": {"$first": 2}}

tests/test_query.py

@@ -456,6 +456,16 @@ class ParameterTestCase:
         ),
         expected_query=[{"$group": {"_id": "$owner_id", "sss": {"$first": "sss"}}}],
     ),
+    ParameterTestCase(
+        compiled_query=(
+            Aggify(PostDocument)
+            .group("stat__like_count")
+            .annotate("sss", "first", "sss")
+        ),
+        expected_query=[
+            {"$group": {"_id": "$stat.like_count", "sss": {"$first": "sss"}}}
+        ],
+    ),
 ]