add internal forwardref stub

ormar/fields/foreign_key.py

@@ -3,12 +3,13 @@ from dataclasses import dataclass
 from typing import Any, List, Optional, TYPE_CHECKING, Tuple, Type, Union
 
 from pydantic import BaseModel, create_model
-from pydantic.typing import ForwardRef, evaluate_forwardref
+from pydantic.typing import evaluate_forwardref
 from sqlalchemy import UniqueConstraint
 
 import ormar  # noqa I101
 from ormar.exceptions import RelationshipInstanceError
 from ormar.fields.base import BaseField
+from ormar.protocols.forward_ref import ForwardRef
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar.models import Model, NewBaseModel

ormar/fields/many_to_many.py

@@ -1,9 +1,10 @@
 from typing import Any, List, Optional, TYPE_CHECKING, Tuple, Type, Union
 
-from pydantic.typing import ForwardRef, evaluate_forwardref
+from pydantic.typing import evaluate_forwardref
 import ormar  # noqa: I100
 from ormar.fields import BaseField
 from ormar.fields.foreign_key import ForeignKeyField
+from ormar.protocols.forward_ref import ForwardRef
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar.models import Model

ormar/models/helpers/models.py

@@ -1,9 +1,10 @@
 from typing import Dict, List, Optional, TYPE_CHECKING, Tuple, Type
 
-from pydantic.typing import ForwardRef
+
 import ormar  # noqa: I100
 from ormar.fields.foreign_key import ForeignKeyField
 from ormar.models.helpers.pydantic import populate_pydantic_default_values
+from ormar.protocols.forward_ref import ForwardRef
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar import Model

ormar/protocols/forward_ref.py

@@ -0,0 +1,22 @@
+import sys
+from typing import Any, TYPE_CHECKING
+
+if sys.version_info < (3, 7):  # pragma: no cover
+    if TYPE_CHECKING:
+
+        class ForwardRef:
+
+            _gorg = None
+
+            def __init__(self, args: Any) -> None:
+                pass
+
+            def _eval_type(self, globalns: Any, localns: Any) -> Any:
+                pass
+
+    else:
+        from typing import _ForwardRef as ForwardRef
+else:
+    from typing import ForwardRef
+
+ForwardRef = ForwardRef