Fix enum member names for object values to use title/name/const keys (#2596)

* Add support for enum members with object values in JSON schema

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

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

Author: koxudaxi

src/datamodel_code_generator/parser/jsonschema.py

@@ -1539,6 +1539,17 @@ def parse_enum_as_literal(self, obj: JsonSchemaObject) -> DataType:
         """Parse enum values as a Literal type."""
         return self.data_type(literals=[i for i in obj.enum if i is not None])
 
+    @classmethod
+    def _get_field_name_from_dict_enum(cls, enum_part: dict[str, Any], index: int) -> str:
+        """Extract field name from dict enum value using title, name, or const keys."""
+        if enum_part.get("title"):
+            return str(enum_part["title"])
+        if enum_part.get("name"):
+            return str(enum_part["name"])
+        if "const" in enum_part:
+            return str(enum_part["const"])
+        return f"value_{index}"
+
     def parse_enum(
         self,
         name: str,
@@ -1575,6 +1586,8 @@ def parse_enum(
                 default = enum_part
                 if obj.x_enum_varnames:
                     field_name = obj.x_enum_varnames[i]
+                elif isinstance(enum_part, dict):
+                    field_name = self._get_field_name_from_dict_enum(enum_part, i)
                 else:
                     prefix = obj.type if isinstance(obj.type, str) else type(enum_part).__name__
                     field_name = f"{prefix}_{enum_part}"

tests/data/expected/main/jsonschema/jsonschema_enum_object_values.py

@@ -0,0 +1,43 @@
+# generated by datamodel-codegen:
+#   filename:  enum_object_values.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from enum import Enum
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class CountryWithTitle(Enum):
+    USA = {'title': 'USA', 'code': 'US'}
+    CANADA = {'title': 'CANADA', 'code': 'CA'}
+
+
+class CountryWithName(Enum):
+    USA = {'name': 'USA', 'code': 'US'}
+    CANADA = {'name': 'CANADA', 'code': 'CA'}
+
+
+class CountryWithConst(Enum):
+    us_value = {'const': 'us_value'}
+    ca_value = {'const': 'ca_value'}
+
+
+class CountryNoIdentifier(Enum):
+    value_0 = {'code': 'US'}
+    value_1 = {'code': 'CA'}
+
+
+class CountryDuplicateTitle(Enum):
+    SAME = {'title': 'SAME', 'code': 'US'}
+    SAME_1 = {'title': 'SAME', 'code': 'CA'}
+
+
+class EnumObjectTest(BaseModel):
+    country_with_title: Optional[CountryWithTitle] = None
+    country_with_name: Optional[CountryWithName] = None
+    country_with_const: Optional[CountryWithConst] = None
+    country_no_identifier: Optional[CountryNoIdentifier] = None
+    country_duplicate_title: Optional[CountryDuplicateTitle] = None

tests/data/jsonschema/enum_object_values.json

@@ -0,0 +1,37 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "EnumObjectTest",
+  "type": "object",
+  "properties": {
+    "country_with_title": {
+      "enum": [
+        {"title": "USA", "code": "US"},
+        {"title": "CANADA", "code": "CA"}
+      ]
+    },
+    "country_with_name": {
+      "enum": [
+        {"name": "USA", "code": "US"},
+        {"name": "CANADA", "code": "CA"}
+      ]
+    },
+    "country_with_const": {
+      "enum": [
+        {"const": "us_value"},
+        {"const": "ca_value"}
+      ]
+    },
+    "country_no_identifier": {
+      "enum": [
+        {"code": "US"},
+        {"code": "CA"}
+      ]
+    },
+    "country_duplicate_title": {
+      "enum": [
+        {"title": "SAME", "code": "US"},
+        {"title": "SAME", "code": "CA"}
+      ]
+    }
+  }
+}

tests/main/jsonschema/test_main_jsonschema.py

@@ -2977,6 +2977,16 @@ def test_main_jsonschema_empty_items_array(output_file: Path) -> None:
     )
 
 
+def test_main_jsonschema_enum_object_values(output_file: Path) -> None:
+    """Test that enum with object values uses title/name/const for member names (issue #1620)."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "enum_object_values.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+    )
+
+
 def test_main_jsonschema_collapse_root_models_empty_union(output_file: Path) -> None:
     """Test that collapse-root-models with empty union fallback generates Any instead of invalid Union syntax.