chore: attempt to be more informative for missing attributes

JohnVillalovos · JohnVillalovos · commit dafe0becc82f · 2021-11-20T15:50:25.000-08:00
A commonly reported issue from users on Gitter is that they get an
AttributeError for an attribute that should be present. This is often
caused due to the fact that they used the `list()` method to retrieve
the object and objects retrieved this way often only have a subset of
the full data.

Add more details in the AttributeError message that explains the
situation to users. This will hopefully allow them to resolve the
issue.
diff --git a/gitlab/base.py b/gitlab/base.py
@@ -45,13 +45,19 @@ class RESTObject(object):
 
     _id_attr: Optional[str] = "id"
     _attrs: Dict[str, Any]
+    _list_created_object: bool  # Indicates if object was created from a list() action
     _module: ModuleType
     _parent_attrs: Dict[str, Any]
     _short_print_attr: Optional[str] = None
     _updated_attrs: Dict[str, Any]
     manager: "RESTManager"
 
-    def __init__(self, manager: "RESTManager", attrs: Dict[str, Any]) -> None:
+    def __init__(
+        self,
+        manager: "RESTManager",
+        attrs: Dict[str, Any],
+        list_created_object: bool = False,
+    ) -> None:
         if not isinstance(attrs, dict):
             raise GitlabParsingError(
                 "Attempted to initialize RESTObject with a non-dictionary value: "
@@ -64,6 +70,7 @@ def __init__(self, manager: "RESTManager", attrs: Dict[str, Any]) -> None:
                 "_attrs": attrs,
                 "_updated_attrs": {},
                 "_module": importlib.import_module(self.__module__),
+                "_list_created_object": list_created_object,
             }
         )
         self.__dict__["_parent_attrs"] = self.manager.parent_attrs
@@ -107,7 +114,15 @@ def __getattr__(self, name: str) -> Any:
                 try:
                     return self.__dict__["_parent_attrs"][name]
                 except KeyError:
-                    raise AttributeError(name)
+                    message = name
+                    if self._list_created_object:
+                        message = (
+                            f"Unable to find attribute {name!r}. This object was "
+                            f"created via a list() call and only a subset of the data "
+                            f"may be present. To ensure all data is present get the "
+                            f"object using a get(object.id) call"
+                        )
+                    raise AttributeError(message)
 
     def __setattr__(self, name: str, value: Any) -> None:
         self.__dict__["_updated_attrs"][name] = value
@@ -225,7 +240,7 @@ def __next__(self) -> RESTObject:
 
     def next(self) -> RESTObject:
         data = self._list.next()
-        return self._obj_cls(self.manager, data)
+        return self._obj_cls(manager=self.manager, attrs=data, list_created_object=True)
 
     @property
     def current_page(self) -> int:
diff --git a/gitlab/mixins.py b/gitlab/mixins.py
@@ -240,9 +240,12 @@ def list(self, **kwargs: Any) -> Union[base.RESTObjectList, List[base.RESTObject
             assert self._obj_cls is not None
         obj = self.gitlab.http_list(path, **data)
         if isinstance(obj, list):
-            return [self._obj_cls(self, item) for item in obj]
+            return [
+                self._obj_cls(manager=self, attrs=item, list_created_object=True)
+                for item in obj
+            ]
         else:
-            return base.RESTObjectList(self, self._obj_cls, obj)
+            return base.RESTObjectList(manager=self, obj_cls=self._obj_cls, _list=obj)
 
 
 class RetrieveMixin(ListMixin, GetMixin):
diff --git a/tests/unit/test_base.py b/tests/unit/test_base.py
@@ -90,6 +90,22 @@ def test_instantiate_non_dict(self, fake_gitlab, fake_manager):
         with pytest.raises(gitlab.exceptions.GitlabParsingError):
             FakeObject(fake_manager, ["a", "list", "fails"])
 
+    def test_missing_attribute(self, fake_gitlab, fake_manager):
+        obj = FakeObject(manager=fake_manager, attrs={"foo": "bar"})
+        with pytest.raises(AttributeError) as excinfo:
+            obj.missing_attribute
+        assert str(excinfo.value) == "missing_attribute"
+        assert "object was created via a list()" not in str(excinfo.value)
+
+        # Test for more informative message if a list() created object
+        obj = FakeObject(
+            manager=fake_manager, attrs={"foo": "bar"}, list_created_object=True
+        )
+        with pytest.raises(AttributeError) as excinfo:
+            obj.missing_attribute
+        assert "missing_attribute" in str(excinfo.value)
+        assert "object was created via a list()" in str(excinfo.value)
+
     def test_picklability(self, fake_manager):
         obj = FakeObject(fake_manager, {"foo": "bar"})
         original_obj_module = obj._module
