Fix "A Parser can not resolve classes" error when allOf references enum from another schema (#2636)

* Fix unresolved class references in allOf enum handling and add corresponding tests

* Add allOf enum reference handling and corresponding tests

* Add test for allOf referencing enum without external $ref

Author: koxudaxi

src/datamodel_code_generator/parser/jsonschema.py

@@ -1585,7 +1585,32 @@ def parse_all_of(
                 and single_obj.ref_type == JSONReference.LOCAL
                 and get_model_by_path(self.raw_obj, single_obj.ref[2:].split("/")).get("enum")
             ):
-                return self.get_ref_data_type(single_obj.ref)
+                ref_data_type = self.get_ref_data_type(single_obj.ref)
+
+                full_path = self.model_resolver.join_path(path)
+                existing_ref = self.model_resolver.references.get(full_path)
+                if existing_ref is not None and not existing_ref.loaded:
+                    reference = self.model_resolver.add(path, name, class_name=True, loaded=True)
+                    field = self.data_model_field_type(
+                        name=None,
+                        data_type=ref_data_type,
+                        required=True,
+                    )
+                    data_model_root = self.data_model_root_type(
+                        reference=reference,
+                        fields=[field],
+                        custom_base_class=obj.custom_base_path or self.base_class,
+                        custom_template_dir=self.custom_template_dir,
+                        extra_template_data=self.extra_template_data,
+                        path=self.current_source_path,
+                        description=obj.description if self.use_schema_description else None,
+                        nullable=obj.type_has_null,
+                        treat_dot_as_module=self.treat_dot_as_module,
+                    )
+                    self.results.append(data_model_root)
+                    return self.data_type(reference=reference)
+
+                return ref_data_type
 
         merged_all_of_obj = self._merge_all_of_object(obj)
         if merged_all_of_obj:

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

@@ -0,0 +1,20 @@
+# generated by datamodel-codegen:
+#   filename:  allof_enum_no_external_ref.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from enum import Enum
+from typing import Any
+
+from pydantic import BaseModel
+
+
+class Model(BaseModel):
+    __root__: Any
+
+
+class MassUnit(Enum):
+    g = 'g'
+    kg = 'kg'
+    t = 't'

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

@@ -0,0 +1,28 @@
+# generated by datamodel-codegen:
+#   filename:  allof_enum_ref.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from enum import Enum
+from typing import Any, Optional
+
+from pydantic import BaseModel
+
+
+class Model(BaseModel):
+    __root__: Any
+
+
+class MassUnit(Enum):
+    g = 'g'
+    kg = 'kg'
+    t = 't'
+
+
+class QuantityTrunc(BaseModel):
+    __root__: MassUnit
+
+
+class CreateOrderByEstimateRequest(BaseModel):
+    quantity_trunc: Optional[QuantityTrunc] = None

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

@@ -0,0 +1,24 @@
+# generated by datamodel-codegen:
+#   filename:  allof_enum_ref.yaml
+#   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 MassUnit(Enum):
+    g = 'g'
+    kg = 'kg'
+    t = 't'
+
+
+class QuantityTrunc(BaseModel):
+    __root__: MassUnit
+
+
+class CreateOrderByEstimateRequest(BaseModel):
+    quantity_trunc: Optional[QuantityTrunc] = None

tests/data/jsonschema/allof_enum_no_external_ref.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "QuantityTrunc": {
+      "type": "string",
+      "description": "Quantity truncation setting",
+      "allOf": [
+        {
+          "$ref": "#/definitions/MassUnit"
+        }
+      ]
+    },
+    "MassUnit": {
+      "type": "string",
+      "enum": ["g", "kg", "t"]
+    }
+  }
+}

tests/data/jsonschema/allof_enum_ref.json

@@ -0,0 +1,26 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "CreateOrderByEstimateRequest": {
+      "type": "object",
+      "properties": {
+        "quantity_trunc": {
+          "$ref": "#/definitions/QuantityTrunc"
+        }
+      }
+    },
+    "QuantityTrunc": {
+      "type": "string",
+      "description": "Quantity truncation setting",
+      "allOf": [
+        {
+          "$ref": "#/definitions/MassUnit"
+        }
+      ]
+    },
+    "MassUnit": {
+      "type": "string",
+      "enum": ["g", "kg", "t"]
+    }
+  }
+}

tests/data/openapi/allof_enum_ref.yaml

@@ -0,0 +1,23 @@
+openapi: 3.0.1
+info:
+  title: Test API
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    CreateOrderByEstimateRequest:
+      type: object
+      properties:
+        quantity_trunc:
+          $ref: '#/components/schemas/QuantityTrunc'
+    QuantityTrunc:
+      type: string
+      description: Quantity truncation setting
+      allOf:
+        - $ref: '#/components/schemas/MassUnit'
+    MassUnit:
+      type: string
+      enum:
+        - g
+        - kg
+        - t

tests/main/jsonschema/test_main_jsonschema.py

@@ -1385,6 +1385,30 @@ def test_main_jsonschema_subclass_enum(output_file: Path) -> None:
     )
 
 
+def test_main_jsonschema_allof_enum_ref(output_file: Path) -> None:
+    """Test allOf referencing enum from another schema."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "allof_enum_ref.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+    )
+
+
+def test_main_jsonschema_allof_enum_no_external_ref(output_file: Path) -> None:
+    """Test allOf referencing enum without external $ref.
+
+    This covers the case where existing_ref is None in parse_all_of,
+    so the schema is optimized to directly return the enum reference.
+    """
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "allof_enum_no_external_ref.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+    )
+
+
 @pytest.mark.skipif(
     black.__version__.split(".")[0] == "22",
     reason="Installed black doesn't support the old style",

tests/main/openapi/test_main_openapi.py

@@ -3308,3 +3308,13 @@ def test_warning_empty_schemas_with_paths(tmp_path: Path) -> None:
 
     with pytest.warns(UserWarning, match=r"No schemas found.*--openapi-scopes paths"), contextlib.suppress(Exception):
         generate(openapi_file)
+
+
+def test_main_allof_enum_ref(output_file: Path) -> None:
+    """Test OpenAPI generation with allOf referencing enum from another schema."""
+    run_main_and_assert(
+        input_path=OPEN_API_DATA_PATH / "allof_enum_ref.yaml",
+        output_path=output_file,
+        input_file_type=None,
+        assert_func=assert_file_content,
+    )