From f6c74a55d5b272add88d4cbe2efa46c4abc1760f Mon Sep 17 00:00:00 2001
From: Rory Byrne <rory@rory.bio>
Date: Mon, 8 Aug 2022 20:33:30 +0100
Subject: [PATCH] feat: pass config to NamedTuple fields (#4225)

* feat: pass config to create_model_from_namedtuple

* feat: tests for arbitrary_types_allowed in NamedTuple fields

* misc: add changelog file for the PR
---
 changes/4219-synek.md         |  1 +
 pydantic/validators.py        |  7 +++++--
 tests/test_annotated_types.py | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 changes/4219-synek.md

diff --git a/changes/4219-synek.md b/changes/4219-synek.md
new file mode 100644
index 0000000000..3dfa1e9898
--- /dev/null
+++ b/changes/4219-synek.md
@@ -0,0 +1 @@
+Use parent model's `Config` when validating nested `NamedTuple` fields.
diff --git a/pydantic/validators.py b/pydantic/validators.py
index 3d6e5217ff..c6b92f8db2 100644
--- a/pydantic/validators.py
+++ b/pydantic/validators.py
@@ -567,11 +567,14 @@ def pattern_validator(v: Any) -> Pattern[str]:
 NamedTupleT = TypeVar('NamedTupleT', bound=NamedTuple)
 
 
-def make_namedtuple_validator(namedtuple_cls: Type[NamedTupleT]) -> Callable[[Tuple[Any, ...]], NamedTupleT]:
+def make_namedtuple_validator(
+    namedtuple_cls: Type[NamedTupleT], config: Type['BaseConfig']
+) -> Callable[[Tuple[Any, ...]], NamedTupleT]:
     from .annotated_types import create_model_from_namedtuple
 
     NamedTupleModel = create_model_from_namedtuple(
         namedtuple_cls,
+        __config__=config,
         __module__=namedtuple_cls.__module__,
     )
     namedtuple_cls.__pydantic_model__ = NamedTupleModel  # type: ignore[attr-defined]
@@ -704,7 +707,7 @@ def find_validators(  # noqa: C901 (ignore complexity)
         return
     if is_namedtuple(type_):
         yield tuple_validator
-        yield make_namedtuple_validator(type_)
+        yield make_namedtuple_validator(type_, config)
         return
     if is_typeddict(type_):
         yield make_typeddict_validator(type_, config)
diff --git a/tests/test_annotated_types.py b/tests/test_annotated_types.py
index 43c13d08b5..e8b6cb9a06 100644
--- a/tests/test_annotated_types.py
+++ b/tests/test_annotated_types.py
@@ -151,6 +151,29 @@ class Model(BaseModel):
         Model.parse_obj({'t': [-1]})
 
 
+def test_namedtuple_arbitrary_type():
+    class CustomClass:
+        pass
+
+    class Tup(NamedTuple):
+        c: CustomClass
+
+    class Model(BaseModel):
+        x: Tup
+
+        class Config:
+            arbitrary_types_allowed = True
+
+    data = {'x': Tup(c=CustomClass())}
+    model = Model.parse_obj(data)
+    assert isinstance(model.x.c, CustomClass)
+
+    with pytest.raises(RuntimeError):
+
+        class ModelNoArbitraryTypes(BaseModel):
+            x: Tup
+
+
 def test_typeddict():
     class TD(TypedDict):
         a: int