fix ClassVars, better fix for #3679

pydantic · May 14, 2022 · 98dab9e · 98dab9e
1 parent 9baec86
commit 98dab9e
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Showing 3 changed files with 10 additions and 5 deletions.
diff --git a/changes/3679-samuelcolvin.md b/changes/3679-samuelcolvin.md
@@ -1 +1 @@
-Allow self referencing `ClassVar`s in models but checking for class vars after forward refs are resolved.
+Allow self referencing `ClassVar`s in models.
diff --git a/pydantic/fields.py b/pydantic/fields.py
@@ -38,7 +38,6 @@
     display_as_type,
     get_args,
     get_origin,
-    is_classvar,
     is_literal_type,
     is_new_type,
     is_none_type,
@@ -614,8 +613,6 @@ def _type_analysis(self) -> None:  # noqa: C901 (ignore complexity)
             return
         elif origin is Callable:
             return
-        elif is_classvar(origin):
-            return
         elif is_union(origin):
             types_ = []
             for type_ in get_args(self.type_):

diff --git a/pydantic/typing.py b/pydantic/typing.py
@@ -387,7 +387,15 @@ def _check_classvar(v: Optional[Type[Any]]) -> bool:
 
 
 def is_classvar(ann_type: Type[Any]) -> bool:
-    return _check_classvar(ann_type) or _check_classvar(get_origin(ann_type))
+    if _check_classvar(ann_type) or _check_classvar(get_origin(ann_type)):
+        return True
+
+    # this is an ugly workaround for class vars that contain forward references and are therefore themselves
+    # forward references, see #3679
+    if ann_type.__class__ == ForwardRef and ann_type.__forward_arg__.startswith('ClassVar['):
+        return True
+
+    return False
 
 
 def update_field_forward_refs(field: 'ModelField', globalns: Any, localns: Any) -> None: