Add support for setting strict_nullable from CLI

fastapi_code_generator/__main__.py

@@ -7,7 +7,6 @@
 import typer
 from datamodel_code_generator import DataModelType, LiteralType, PythonVersion, chdir
 from datamodel_code_generator.format import CodeFormatter
-from datamodel_code_generator.imports import Import, Imports
 from datamodel_code_generator.model import get_data_model_types
 from datamodel_code_generator.reference import Reference
 from datamodel_code_generator.types import DataType
@@ -65,6 +64,11 @@ def main(
     python_version: PythonVersion = typer.Option(
         PythonVersion.PY_39.value, "--python-version", "-p"
     ),
+    strict_nullable: bool = typer.Option(
+        False,
+        "--strict-nullable",
+        help="Strictly follow nullable attribute in OpenAPI spec",
+    ),
 ) -> None:
     input_name: str = input_file
     input_text: str
@@ -89,6 +93,7 @@ def main(
         specify_tags=specify_tags,
         output_model_type=output_model_type,
         python_version=python_version,
+        strict_nullable=strict_nullable,
     )
 
 
@@ -117,6 +122,7 @@ def generate_code(
     specify_tags: Optional[str] = None,
     output_model_type: DataModelType = DataModelType.PydanticBaseModel,
     python_version: PythonVersion = PythonVersion.PY_39,
+    strict_nullable: bool = False,
 ) -> None:
     if not model_path:
         model_path = MODEL_PATH
@@ -142,6 +148,7 @@ def generate_code(
         dump_resolve_reference_action=data_model_types.dump_resolve_reference_action,
         custom_template_dir=model_template_dir,
         target_python_version=python_version,
+        strict_nullable=strict_nullable,
     )
 
     with chdir(output_dir):

tests/data/expected/openapi/default_template/nullable_test/main.py

@@ -0,0 +1,24 @@
+# generated by fastapi-codegen:
+#   filename:  nullable_test.yaml
+#   timestamp: 2020-06-19T00:00:00+00:00
+
+from __future__ import annotations
+
+from fastapi import FastAPI
+
+from .models import User
+
+app = FastAPI(
+    version='1.0.0',
+    title='Nullable Test API',
+    description='API for testing nullable field behavior',
+    servers=[{'url': 'http://api.example.com/v1'}],
+)
+
+
+@app.get('/users', response_model=User)
+def get_user_details() -> User:
+    """
+    Get user details
+    """
+    pass

tests/data/expected/openapi/default_template/nullable_test/models.py

@@ -0,0 +1,21 @@
+# generated by fastapi-codegen:
+#   filename:  nullable_test.yaml
+#   timestamp: 2020-06-19T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Optional
+
+from pydantic import BaseModel, Field
+
+
+class User(BaseModel):
+    id: int
+    username: str
+    email: Optional[str] = Field(
+        None, description="User's email address (explicitly nullable)"
+    )
+    phone: str = Field(..., description="User's phone number (explicitly non-nullable)")
+    nickname: Optional[str] = Field(
+        None, description="User's nickname (implicitly nullable)"
+    )

tests/data/expected/openapi/default_template/nullable_test_strict/main.py

@@ -0,0 +1,24 @@
+# generated by fastapi-codegen:
+#   filename:  nullable_test.yaml
+#   timestamp: 2020-06-19T00:00:00+00:00
+
+from __future__ import annotations
+
+from fastapi import FastAPI
+
+from .models import User
+
+app = FastAPI(
+    version='1.0.0',
+    title='Nullable Test API',
+    description='API for testing nullable field behavior',
+    servers=[{'url': 'http://api.example.com/v1'}],
+)
+
+
+@app.get('/users', response_model=User)
+def get_user_details() -> User:
+    """
+    Get user details
+    """
+    pass

tests/data/expected/openapi/default_template/nullable_test_strict/models.py

@@ -0,0 +1,21 @@
+# generated by fastapi-codegen:
+#   filename:  nullable_test.yaml
+#   timestamp: 2020-06-19T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Optional
+
+from pydantic import BaseModel, Field
+
+
+class User(BaseModel):
+    id: int
+    username: str
+    email: Optional[str] = Field(
+        None, description="User's email address (explicitly nullable)"
+    )
+    phone: str = Field(..., description="User's phone number (explicitly non-nullable)")
+    nickname: Optional[str] = Field(
+        None, description="User's nickname (implicitly nullable)"
+    )

tests/data/openapi/default_template/nullable_test.yaml

@@ -0,0 +1,44 @@
+openapi: "3.0.0"
+info:
+  version: 1.0.0
+  title: Nullable Test API
+  description: API for testing nullable field behavior
+servers:
+  - url: http://api.example.com/v1
+paths:
+  /users:
+    get:
+      summary: Get user details
+      operationId: getUserDetails
+      responses:
+        "200":
+          description: User details
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/User"
+components:
+  schemas:
+    User:
+      type: object
+      required:
+        - id
+        - phone
+        - username
+      properties:
+        id:
+          type: integer
+          format: int64
+        username:
+          type: string
+        email:
+          type: string
+          nullable: true
+          description: User's email address (explicitly nullable)
+        phone:
+          type: string
+          nullable: false
+          description: User's phone number (explicitly non-nullable)
+        nickname:
+          type: string
+          description: User's nickname (implicitly nullable)

tests/test_generate.py

@@ -203,3 +203,26 @@ def test_generate_modify_specific_routers(oas_file):
                     assert output_inner.read_text() == expected_inner.read_text()
             else:
                 assert output_file.read_text() == expected_file.read_text(), oas_file
+
+
+@freeze_time("2020-06-19")
+def test_generate_nullable_strict():
+    oas_file = DATA_DIR / OPEN_API_DEFAULT_TEMPLATE_DIR_NAME / 'nullable_test.yaml'
+    with TemporaryDirectory() as tmp_dir:
+        output_dir = Path(tmp_dir) / (oas_file.stem + '_strict')
+        generate_code(
+            input_name=oas_file.name,
+            input_text=oas_file.read_text(),
+            encoding=ENCODING,
+            output_dir=output_dir,
+            template_dir=None,
+            strict_nullable=True,
+        )
+        expected_dir = (
+            EXPECTED_DIR / OPEN_API_DEFAULT_TEMPLATE_DIR_NAME / "nullable_test_strict"
+        )
+        output_files = sorted(list(output_dir.glob("**/*.py")))
+        expected_files = sorted(list(expected_dir.glob("**/*.py")))
+        assert [f.name for f in output_files] == [f.name for f in expected_files]
+        for output_file, expected_file in zip(output_files, expected_files):
+            assert output_file.read_text() == expected_file.read_text()