Fix check of Literal in replace_pydantic_types (#1445)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Patrick Arminio <[email protected]>

RELEASE.md

@@ -0,0 +1,3 @@
+Release type: patch
+
+This release fixes an issubclass test failing for `Literal`s in the experimental `pydantic` integration.

strawberry/experimental/pydantic/object_type.py

@@ -6,6 +6,7 @@
 
 from pydantic import BaseModel
 from pydantic.fields import ModelField
+from typing_extensions import Literal
 
 import strawberry
 from strawberry.arguments import UNSET
@@ -24,6 +25,10 @@
 
 
 def replace_pydantic_types(type_: Any):
+    origin = getattr(type_, "__origin__", None)
+    if origin is Literal:
+        # Literal does not have types in its __args__ so we return early
+        return type_
     if hasattr(type_, "__args__"):
         new_type = type_.copy_with(
             tuple(replace_pydantic_types(t) for t in type_.__args__)

tests/experimental/pydantic/test_fields.py

@@ -1,6 +1,7 @@
 import pytest
 
 import pydantic
+from typing_extensions import Literal
 
 import strawberry
 from strawberry.type import StrawberryOptional
@@ -128,3 +129,20 @@ class Model(pydantic.BaseModel):
         @strawberry.experimental.pydantic.type(Model)
         class Type:
             field: strawberry.auto
+
+
+def test_literal_types():
+    class Model(pydantic.BaseModel):
+        field: Literal["field"]
+
+    @strawberry.experimental.pydantic.type(Model)
+    class Type:
+        field: strawberry.auto
+
+    definition: TypeDefinition = Type._type_definition
+    assert definition.name == "Type"
+
+    [field] = definition.fields
+
+    assert field.python_name == "field"
+    assert field.type == Literal["field"]