create_model support generics model (#3946)

* create_model support generics model

* fix change.

Co-authored-by: chenyijian <chenyijian@mycapital.net>
Co-authored-by: Samuel Colvin <samcolvin@gmail.com>

changes/3945-hot123s.md

@@ -0,0 +1 @@
+Support generics model with `create_model`

pydantic/main.py

@@ -4,7 +4,7 @@
 from enum import Enum
 from functools import partial
 from pathlib import Path
-from types import FunctionType
+from types import FunctionType, prepare_class, resolve_bases
 from typing import (
     TYPE_CHECKING,
     AbstractSet,
@@ -996,8 +996,12 @@ def create_model(
     namespace.update(fields)
     if __config__:
         namespace['Config'] = inherit_config(__config__, BaseConfig)
-
-    return type(__model_name, __base__, namespace, **__cls_kwargs__)
+    resolved_bases = resolve_bases(__base__)
+    meta, ns, kwds = prepare_class(__model_name, resolved_bases, kwds=__cls_kwargs__)
+    if resolved_bases is not __base__:
+        ns['__orig_bases__'] = __base__
+    namespace.update(ns)
+    return meta(__model_name, resolved_bases, namespace, **kwds)
 
 
 _missing = object()

tests/test_create_model.py

@@ -1,6 +1,9 @@
+from typing import Generic, TypeVar
+
 import pytest
 
 from pydantic import BaseModel, Extra, Field, ValidationError, create_model, errors, validator
+from pydantic.generics import GenericModel
 
 
 def test_create_model():
@@ -205,3 +208,17 @@ class Config:
 
     m2 = create_model('M2', __config__=Config, a=(str, Field(...)))
     assert m2.schema()['properties'] == {'a': {'title': 'A', 'description': 'descr', 'type': 'string'}}
+
+
+def test_generics_model():
+    T = TypeVar('T')
+
+    class TestGenericModel(GenericModel):
+        pass
+
+    AAModel = create_model(
+        'AAModel', __base__=(TestGenericModel, Generic[T]), __cls_kwargs__={'orm_mode': True}, aa=(int, Field(0))
+    )
+    result = AAModel[int](aa=1)
+    assert result.aa == 1
+    assert result.__config__.orm_mode is True