Fix required list fields ignoring empty default values

Author: koxudaxi

src/datamodel_code_generator/model/pydantic/base_model.py

@@ -220,7 +220,7 @@ 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()
@@ -249,7 +249,7 @@ 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/jsonschema/has_default_value.py

@@ -25,11 +25,15 @@ class Pet(BaseModel):
 
 
 class Family(BaseModel):
-    __root__: list[ID]
+    __root__: list[ID] = Field(
+        default_factory=lambda: [ID.parse_obj(v) for v in ['abc', 'efg']]
+    )
 
 
 class FamilyPets(BaseModel):
-    __root__: list[Pet]
+    __root__: list[Pet] = Field(
+        default_factory=lambda: [Pet.parse_obj(v) for v in ['taro', 'shiro']]
+    )
 
 
 class Person(BaseModel):