Use default value for ref property

.changeset/use_default_value_for_ref_property.md

@@ -0,0 +1,9 @@
+---
+default: patch
+---
+
+# Use default value for ref property
+
+#1202 by @github-abcde
+
+Use defined default value for referenced properties of a model instead of always defaulting to `UNSET` in the generated code.

end_to_end_tests/baseline_openapi_3.0.json

@@ -2563,6 +2563,15 @@
           }
         }
       },
+      "AModelWithOptionalPropertyRefAndDefaultValue": {
+        "type": "object",
+        "properties": {
+          "enum_property_ref": {
+            "$ref": "#/components/schemas/AnEnum",
+            "default": "FIRST_VALUE"
+          }
+        }
+      },
       "ModelWithDateTimeProperty": {
         "type": "object",
         "properties": {

end_to_end_tests/baseline_openapi_3.1.yaml

@@ -2555,6 +2555,15 @@ info:
         }
       }
     },
+    "AModelWithOptionalPropertyRefAndDefaultValue": {
+      "type": "object",
+      "properties": {
+        "enum_property_ref": {
+          "$ref": "#/components/schemas/AnEnum",
+          "default": "FIRST_VALUE"
+        }
+      }
+    },
     "ModelWithDateTimeProperty": {
       "type": "object",
       "properties": {

end_to_end_tests/golden-record/my_test_api_client/models/__init__.py

@@ -4,6 +4,7 @@
 from .a_discriminated_union_type_2 import ADiscriminatedUnionType2
 from .a_form_data import AFormData
 from .a_model import AModel
+from .a_model_with_optional_property_ref_and_default_value import AModelWithOptionalPropertyRefAndDefaultValue
 from .a_model_with_properties_reference_that_are_not_object import AModelWithPropertiesReferenceThatAreNotObject
 from .all_of_has_properties_but_no_type import AllOfHasPropertiesButNoType
 from .all_of_has_properties_but_no_type_type_enum import AllOfHasPropertiesButNoTypeTypeEnum
@@ -98,6 +99,7 @@
     "AllOfSubModel",
     "AllOfSubModelTypeEnum",
     "AModel",
+    "AModelWithOptionalPropertyRefAndDefaultValue",
     "AModelWithPropertiesReferenceThatAreNotObject",
     "AnAllOfEnum",
     "AnArrayWithACircularRefInItemsObjectAdditionalPropertiesAItem",

end_to_end_tests/golden-record/my_test_api_client/models/a_model_with_optional_property_ref_and_default_value.py

@@ -0,0 +1,67 @@
+from typing import Any, TypeVar, Union
+
+from attrs import define as _attrs_define
+from attrs import field as _attrs_field
+
+from ..models.an_enum import AnEnum
+from ..types import UNSET, Unset
+
+T = TypeVar("T", bound="AModelWithOptionalPropertyRefAndDefaultValue")
+
+
+@_attrs_define
+class AModelWithOptionalPropertyRefAndDefaultValue:
+    """
+    Attributes:
+        enum_property_ref (Union[Unset, AnEnum]): For testing Enums in all the ways they can be used  Default:
+            AnEnum.FIRST_VALUE.
+    """
+
+    enum_property_ref: Union[Unset, AnEnum] = AnEnum.FIRST_VALUE
+    additional_properties: dict[str, Any] = _attrs_field(init=False, factory=dict)
+
+    def to_dict(self) -> dict[str, Any]:
+        enum_property_ref: Union[Unset, str] = UNSET
+        if not isinstance(self.enum_property_ref, Unset):
+            enum_property_ref = self.enum_property_ref.value
+
+        field_dict: dict[str, Any] = {}
+        field_dict.update(self.additional_properties)
+        field_dict.update({})
+        if enum_property_ref is not UNSET:
+            field_dict["enum_property_ref"] = enum_property_ref
+
+        return field_dict
+
+    @classmethod
+    def from_dict(cls: type[T], src_dict: dict[str, Any]) -> T:
+        d = src_dict.copy()
+        _enum_property_ref = d.pop("enum_property_ref", UNSET)
+        enum_property_ref: Union[Unset, AnEnum]
+        if isinstance(_enum_property_ref, Unset):
+            enum_property_ref = UNSET
+        else:
+            enum_property_ref = AnEnum(_enum_property_ref)
+
+        a_model_with_optional_property_ref_and_default_value = cls(
+            enum_property_ref=enum_property_ref,
+        )
+
+        a_model_with_optional_property_ref_and_default_value.additional_properties = d
+        return a_model_with_optional_property_ref_and_default_value
+
+    @property
+    def additional_keys(self) -> list[str]:
+        return list(self.additional_properties.keys())
+
+    def __getitem__(self, key: str) -> Any:
+        return self.additional_properties[key]
+
+    def __setitem__(self, key: str, value: Any) -> None:
+        self.additional_properties[key] = value
+
+    def __delitem__(self, key: str) -> None:
+        del self.additional_properties[key]
+
+    def __contains__(self, key: str) -> bool:
+        return key in self.additional_properties

openapi_python_client/parser/properties/__init__.py

@@ -120,10 +120,18 @@ def _property_from_ref(
             schemas,
         )
 
-    default = existing.convert_value(parent.default) if parent is not None else None
-    if isinstance(default, PropertyError):
-        default.data = parent or data
-        return default, schemas
+    if hasattr(data, 'default'):
+        default = existing.convert_value(data.default)
+        if isinstance(default, PropertyError):
+            default.data = data
+            return default, schemas
+    elif parent is not None:
+        default = existing.convert_value(parent.default)
+        if isinstance(default, PropertyError):
+            default.data = parent
+            return default, schemas
+    else:
+        default = None
 
     prop = evolve(
         existing,