Fix GraphQL empty list default handling

Author: koxudaxi

src/datamodel_code_generator/model/pydantic/base_model.py

@@ -129,7 +129,6 @@ def _get_strict_field_constraint_value(self, constraint: str, value: Any) -> Any
     def _get_default_as_pydantic_model(self) -> str | None:  # noqa: PLR0911, PLR0912
         if isinstance(self.default, WrappedDefault):
             return f"lambda :{self.default!r}"
-        # Handle the case where self.data_type.is_list is True directly (e.g., GraphQL)
         if self.data_type.is_list and len(self.data_type.data_types) == 1:
             data_type_child = self.data_type.data_types[0]
             if (
@@ -234,7 +233,7 @@ def __str__(self) -> str:  # noqa: PLR0912
             elif isinstance(discriminator, dict):  # pragma: no cover
                 data["discriminator"] = discriminator["propertyName"]
 
-        if self.required:
+        if self.required and not self.has_default:
             default_factory = None
         elif self.default is not UNDEFINED and self.default is not None and "default_factory" not in data:
             default_factory = self._get_default_as_pydantic_model()
@@ -263,7 +262,7 @@ def __str__(self) -> str:  # noqa: PLR0912
 
         if self.use_annotated:
             field_arguments = self._process_annotated_field_arguments(field_arguments)
-        elif self.required:
+        elif self.required and not default_factory:
             field_arguments = ["...", *field_arguments]
         elif not default_factory:
             default_repr = repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)

tests/data/expected/main/graphql/empty_list_default.py

@@ -8,14 +8,27 @@
 
 from pydantic import BaseModel, Field
 
+type Boolean = bool
+"""
+The `Boolean` scalar type represents `true` or `false`.
+"""
+
+
+type String = str
+"""
+The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.
+"""
+
 
 class Container(BaseModel):
-    name: str
+    name: String
     typename__: Literal['Container'] | None = Field('Container', alias='__typename')
 
 
 class PodSpec(BaseModel):
     container_list: list[Container] = Field(default_factory=list)
     container_list_or_none: list[Container | None] = Field(default_factory=list)
-    container_or_none_list_or_none: list[Container | None] | None = Field(default_factory=list)
-    typename__: Literal['PodSpec'] | None = Field('PodSpec', alias='__typename')
+    container_or_none_list_or_none: list[Container | None] | None = Field(
+        default_factory=list
+    )
+    typename__: Literal['PodSpec'] | None = Field('PodSpec', alias='__typename')

tests/data/expected/main/graphql/pydantic_v2_empty_list_default.py

@@ -8,14 +8,27 @@
 
 from pydantic import BaseModel, Field
 
+type Boolean = bool
+"""
+The `Boolean` scalar type represents `true` or `false`.
+"""
+
+
+type String = str
+"""
+The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.
+"""
+
 
 class Container(BaseModel):
-    name: str
+    name: String
     typename__: Literal['Container'] | None = Field('Container', alias='__typename')
 
 
 class PodSpec(BaseModel):
     container_list: list[Container] = Field(default_factory=list)
     container_list_or_none: list[Container | None] = Field(default_factory=list)
-    container_or_none_list_or_none: list[Container | None] | None = Field(default_factory=list)
-    typename__: Literal['PodSpec'] | None = Field('PodSpec', alias='__typename')
+    container_or_none_list_or_none: list[Container | None] | None = Field(
+        default_factory=list
+    )
+    typename__: Literal['PodSpec'] | None = Field('PodSpec', alias='__typename')

tests/data/expected/main/openapi/empty_list_default.py

@@ -4,14 +4,12 @@
 
 from __future__ import annotations
 
-from typing import List, Optional
-
 from pydantic import BaseModel, Field
 
 
 class Container(BaseModel):
-    name: Optional[str] = None
+    name: str | None = None
 
 
 class PodSpec(BaseModel):
-    containers: Optional[List[Container]] = Field(default_factory=list)
+    containers: list[Container] | None = Field(default_factory=list)

tests/data/expected/main/openapi/pydantic_v2_empty_list_default.py

@@ -4,14 +4,12 @@
 
 from __future__ import annotations
 
-from typing import List, Optional
-
 from pydantic import BaseModel, Field
 
 
 class Container(BaseModel):
-    name: Optional[str] = None
+    name: str | None = None
 
 
 class PodSpec(BaseModel):
-    containers: Optional[List[Container]] = Field(default_factory=list)
+    containers: list[Container] | None = Field(default_factory=list)