From fc1c25756a0b41ff68ce541c644456363cd1418b Mon Sep 17 00:00:00 2001
From: Koudai Aono <koxudaxi@gmail.com>
Date: Sun, 17 Apr 2022 01:59:51 +0900
Subject: [PATCH] Fix nested Enum (#747)

---
 datamodel_code_generator/parser/base.py       | 22 +++++++
 .../expected/main/main_nested_enum/output.py  | 32 ++++++++++
 tests/data/openapi/nested_enum.json           | 63 +++++++++++++++++++
 tests/test_main.py                            | 23 +++++++
 4 files changed, 140 insertions(+)
 create mode 100644 tests/data/expected/main/main_nested_enum/output.py
 create mode 100644 tests/data/openapi/nested_enum.json

diff --git a/datamodel_code_generator/parser/base.py b/datamodel_code_generator/parser/base.py
index d0e741223..9d0b3f324 100644
--- a/datamodel_code_generator/parser/base.py
+++ b/datamodel_code_generator/parser/base.py
@@ -571,6 +571,28 @@ def parse(
                         from_ += "."
                     imports.append(Import(from_=from_, import_=import_, alias=alias))
 
+            # extract inherited enum
+            for model in models:
+                if model.fields:
+                    continue
+                enums: List[Enum] = []
+                for base_model in model.base_classes:
+                    if not base_model.reference:
+                        continue
+                    source_model = base_model.reference.source
+                    if isinstance(source_model, Enum):
+                        enums.append(source_model)
+                if enums:
+                    models.insert(
+                        models.index(model),
+                        enums[0].__class__(
+                            fields=[f for e in enums for f in e.fields],
+                            description=model.description,
+                            reference=model.reference,
+                        ),
+                    )
+                    models.remove(model)
+
             if self.reuse_model:
                 model_cache: Dict[Tuple[str, ...], Reference] = {}
                 duplicates = []
diff --git a/tests/data/expected/main/main_nested_enum/output.py b/tests/data/expected/main/main_nested_enum/output.py
new file mode 100644
index 000000000..3073813fa
--- /dev/null
+++ b/tests/data/expected/main/main_nested_enum/output.py
@@ -0,0 +1,32 @@
+# generated by datamodel-codegen:
+#   filename:  nested_enum.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from enum import Enum
+
+from pydantic import BaseModel
+
+
+class State(Enum):
+    field_1 = '1'
+    field_2 = '2'
+
+
+class NestedState1(Enum):
+    field_1 = '1'
+    field_2 = '2'
+
+
+class NestedState2(Enum):
+    field_1 = '1'
+    field_2 = '2'
+
+
+class Result1(BaseModel):
+    state: NestedState1
+
+
+class Result2(BaseModel):
+    state: NestedState2
diff --git a/tests/data/openapi/nested_enum.json b/tests/data/openapi/nested_enum.json
new file mode 100644
index 000000000..2bf582bb0
--- /dev/null
+++ b/tests/data/openapi/nested_enum.json
@@ -0,0 +1,63 @@
+{
+    "openapi": "3.0.0",
+    "info": {
+        "title": "Test API",
+        "version": "1.0"
+    },
+    "paths": {},
+    "components": {
+        "schemas": {
+          "Result1": {
+                "type": "object",
+                "description": "description for Result1",
+                "properties": {
+                    "state": {
+                        "$ref": "#/components/schemas/NestedState1"
+                    }
+                },
+                "required": [
+                    "state"
+                ]
+            },
+            "Result2": {
+                "type": "object",
+                "description": "description for Result2",
+                "properties": {
+                    "state": {
+                        "$ref": "#/components/schemas/NestedState2"
+                    }
+                },
+                "required": [
+                    "state"
+                ]
+            },
+            "NestedState1": {
+                "allOf": [
+                    {
+                        "description": "description for NestedState1"
+                    },
+                    {
+                        "$ref": "#/components/schemas/State"
+                    }
+                ]
+            },
+            "NestedState2": {
+                "allOf": [
+                    {
+                        "description": "description for NestedState2"
+                    },
+                    {
+                        "$ref": "#/components/schemas/State"
+                    }
+                ]
+            },
+            "State": {
+                "type": "string",
+                "enum": [
+                    "1",
+                    "2"
+                ]
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/tests/test_main.py b/tests/test_main.py
index 608a18e6d..af616f9ca 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -3613,3 +3613,26 @@ def test_main_use_annotated_with_field_constraints():
 
     with pytest.raises(SystemExit):
         main()
+
+
+@freeze_time('2019-07-26')
+def test_main_nested_enum():
+    with TemporaryDirectory() as output_dir:
+        output_file: Path = Path(output_dir) / 'output.py'
+        return_code: Exit = main(
+            [
+                '--input',
+                str(OPEN_API_DATA_PATH / 'nested_enum.json'),
+                '--output',
+                str(output_file),
+                '--input-file-type',
+                'openapi',
+            ]
+        )
+        assert return_code == Exit.OK
+        assert (
+            output_file.read_text()
+            == (EXPECTED_MAIN_PATH / 'main_nested_enum' / 'output.py').read_text()
+        )
+    with pytest.raises(SystemExit):
+        main()