Add django decorator

docs/integrations/django.md

@@ -57,6 +57,47 @@ OPENAPI = OpenAPI.from_dict(spec_dict)
 OPENAPI_RESPONSE_CLS = None
 ```
 
+## Decorator
+
+Django can be integrated using [view decorators](https://docs.djangoproject.com/en/5.1/topics/http/decorators/) to apply OpenAPI validation to your application's specific views.
+
+Use `DjangoOpenAPIViewDecorator` with the OpenAPI object to create the decorator.
+
+``` python hl_lines="1 3 6"
+from openapi_core.contrib.django.decorators import DjangoOpenAPIViewDecorator
+
+openapi_validated = FlaskOpenAPIViewDecorator(openapi)
+
+
+@openapi_validated
+def home():
+    return "Welcome home"
+```
+
+You can skip the response validation process by setting `response_cls` to `None`.
+
+``` python hl_lines="5"
+from openapi_core.contrib.django.decorators import DjangoOpenAPIViewDecorator
+
+openapi_validated = DjangoOpenAPIViewDecorator(
+    openapi,
+    response_cls=None,
+)
+```
+
+If you want to decorate a class-based view, you can use the `method_decorator` decorator:
+
+``` python hl_lines="2"
+from django.utils.decorators import method_decorator
+
+@method_decorator(openapi_validated, name='dispatch')
+class MyView(View):
+    decorators = [openapi_validated]
+
+    def get(self, request, *args, **kwargs):
+        return "Welcome home"
+```
+
 ## Low level
 
 The integration defines classes useful for low-level integration.

openapi_core/contrib/django/decorators.py

@@ -0,0 +1,102 @@
+"""OpenAPI core contrib django decorators module"""
+
+from typing import Any
+from typing import Callable
+from typing import Optional
+from typing import Type
+
+from django.conf import settings
+from django.http.request import HttpRequest
+from django.http.response import HttpResponse
+from jsonschema_path import SchemaPath
+
+from openapi_core import OpenAPI
+from openapi_core.contrib.django.handlers import DjangoOpenAPIErrorsHandler
+from openapi_core.contrib.django.handlers import (
+    DjangoOpenAPIValidRequestHandler,
+)
+from openapi_core.contrib.django.integrations import DjangoIntegration
+from openapi_core.contrib.django.providers import get_default_openapi_instance
+from openapi_core.contrib.django.requests import DjangoOpenAPIRequest
+from openapi_core.contrib.django.responses import DjangoOpenAPIResponse
+
+
+class DjangoOpenAPIViewDecorator(DjangoIntegration):
+    valid_request_handler_cls = DjangoOpenAPIValidRequestHandler
+    errors_handler_cls: Type[DjangoOpenAPIErrorsHandler] = (
+        DjangoOpenAPIErrorsHandler
+    )
+
+    def __init__(
+        self,
+        openapi: Optional[OpenAPI] = None,
+        request_cls: Type[DjangoOpenAPIRequest] = DjangoOpenAPIRequest,
+        response_cls: Type[DjangoOpenAPIResponse] = DjangoOpenAPIResponse,
+        errors_handler_cls: Type[
+            DjangoOpenAPIErrorsHandler
+        ] = DjangoOpenAPIErrorsHandler,
+    ):
+        if openapi is None:
+            openapi = get_default_openapi_instance()
+
+        super().__init__(openapi)
+
+        # If OPENAPI_RESPONSE_CLS is defined in settings.py (for custom response classes),
+        # set the response_cls accordingly.
+        if hasattr(settings, "OPENAPI_RESPONSE_CLS"):
+            response_cls = settings.OPENAPI_RESPONSE_CLS
+
+        self.request_cls = request_cls
+        self.response_cls = response_cls
+
+    def __call__(self, view_func: Callable[..., Any]) -> Callable[..., Any]:
+        """
+        Thanks to this method, the class acts as a decorator.
+        Example usage:
+
+            @DjangoOpenAPIViewDecorator()
+            def my_view(request): ...
+
+        """
+
+        def _wrapped_view(
+            request: HttpRequest, *args: Any, **kwargs: Any
+        ) -> HttpResponse:
+            # get_response is the function that we treats
+            # as the "next step" in the chain (i.e., our original view).
+            def get_response(r: HttpRequest) -> HttpResponse:
+                return view_func(r, *args, **kwargs)
+
+            # Create a handler that will validate the request.
+            valid_request_handler = self.valid_request_handler_cls(
+                request, get_response
+            )
+
+            # Validate the request (before running the view).
+            errors_handler = self.errors_handler_cls()
+            response = self.handle_request(
+                request, valid_request_handler, errors_handler
+            )
+
+            # Validate the response (after the view) if should_validate_response() returns True.
+            return self.handle_response(request, response, errors_handler)
+
+        return _wrapped_view
+
+    @classmethod
+    def from_spec(
+        cls,
+        spec: SchemaPath,
+        request_cls: Type[DjangoOpenAPIRequest] = DjangoOpenAPIRequest,
+        response_cls: Type[DjangoOpenAPIResponse] = DjangoOpenAPIResponse,
+        errors_handler_cls: Type[
+            DjangoOpenAPIErrorsHandler
+        ] = DjangoOpenAPIErrorsHandler,
+    ) -> "DjangoOpenAPIViewDecorator":
+        openapi = OpenAPI(spec)
+        return cls(
+            openapi,
+            request_cls=request_cls,
+            response_cls=response_cls,
+            errors_handler_cls=errors_handler_cls,
+        )

openapi_core/contrib/django/middlewares.py

@@ -1,19 +1,17 @@
 """OpenAPI core contrib django middlewares module"""
 
-import warnings
 from typing import Callable
 
 from django.conf import settings
-from django.core.exceptions import ImproperlyConfigured
 from django.http.request import HttpRequest
 from django.http.response import HttpResponse
 
-from openapi_core import OpenAPI
 from openapi_core.contrib.django.handlers import DjangoOpenAPIErrorsHandler
 from openapi_core.contrib.django.handlers import (
     DjangoOpenAPIValidRequestHandler,
 )
 from openapi_core.contrib.django.integrations import DjangoIntegration
+from openapi_core.contrib.django.providers import get_default_openapi_instance
 
 
 class DjangoOpenAPIMiddleware(DjangoIntegration):
@@ -26,19 +24,7 @@ def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
         if hasattr(settings, "OPENAPI_RESPONSE_CLS"):
             self.response_cls = settings.OPENAPI_RESPONSE_CLS
 
-        if not hasattr(settings, "OPENAPI"):
-            if not hasattr(settings, "OPENAPI_SPEC"):
-                raise ImproperlyConfigured(
-                    "OPENAPI_SPEC not defined in settings"
-                )
-            else:
-                warnings.warn(
-                    "OPENAPI_SPEC is deprecated. Use OPENAPI instead.",
-                    DeprecationWarning,
-                )
-                openapi = OpenAPI(settings.OPENAPI_SPEC)
-        else:
-            openapi = settings.OPENAPI
+        openapi = get_default_openapi_instance()
 
         super().__init__(openapi)
 

openapi_core/contrib/django/providers.py

@@ -0,0 +1,31 @@
+"""OpenAPI core contrib django providers module"""
+
+import warnings
+from typing import cast
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+
+from openapi_core import OpenAPI
+
+
+def get_default_openapi_instance() -> OpenAPI:
+    """
+    Retrieves or initializes the OpenAPI instance based on Django settings
+    (either OPENAPI or OPENAPI_SPEC).
+    This function ensures the spec is only loaded once.
+    """
+    if hasattr(settings, "OPENAPI"):
+        # Recommended (newer) approach
+        return cast(OpenAPI, settings.OPENAPI)
+    elif hasattr(settings, "OPENAPI_SPEC"):
+        # Backward compatibility
+        warnings.warn(
+            "OPENAPI_SPEC is deprecated. Use OPENAPI in your settings instead.",
+            DeprecationWarning,
+        )
+        return OpenAPI(settings.OPENAPI_SPEC)
+    else:
+        raise ImproperlyConfigured(
+            "Neither OPENAPI nor OPENAPI_SPEC is defined in Django settings."
+        )

tests/integration/contrib/django/data/v3.0/djangoproject/status/views.py

@@ -0,0 +1,17 @@
+from pathlib import Path
+
+from django.http import HttpResponse
+from jsonschema_path import SchemaPath
+
+from openapi_core.contrib.django.decorators import DjangoOpenAPIViewDecorator
+
+check_minimal_spec = DjangoOpenAPIViewDecorator.from_spec(
+    SchemaPath.from_file_path(
+        Path("tests/integration/data/v3.0/minimal_with_servers.yaml")
+    )
+)
+
+
+@check_minimal_spec
+def get_status(request):
+    return HttpResponse("OK")

tests/integration/contrib/django/data/v3.0/djangoproject/urls.py

@@ -20,6 +20,7 @@
 from djangoproject.pets.views import PetDetailView
 from djangoproject.pets.views import PetListView
 from djangoproject.pets.views import PetPhotoView
+from djangoproject.status.views import get_status
 from djangoproject.tags.views import TagListView
 
 urlpatterns = [
@@ -48,4 +49,9 @@
         TagListView.as_view(),
         name="tag_list_view",
     ),
+    path(
+        "status",
+        get_status,
+        name="get_status_view",
+    ),
 ]

tests/integration/contrib/django/test_django_project.py

@@ -422,3 +422,41 @@ def test_post_valid(self, client, data_gif):
 
         assert response.status_code == 201
         assert not response.content
+
+
+class TestStatusView(BaseTestDjangoProject):
+
+    def test_get_valid(self, client, data_gif):
+        headers = {
+            "HTTP_AUTHORIZATION": "Basic testuser",
+            "HTTP_HOST": "petstore.swagger.io",
+        }
+        from django.conf import settings
+
+        MIDDLEWARE = [
+            v for v in settings.MIDDLEWARE if "openapi_core" not in v
+        ]
+        with override_settings(MIDDLEWARE=MIDDLEWARE):
+            response = client.get("/status", **headers)
+
+        assert response.status_code == 200
+        assert response.content.decode() == "OK"
+
+    def test_post_valid(self, client):
+        data = {"key": "value"}
+        content_type = "application/json"
+        headers = {
+            "HTTP_AUTHORIZATION": "Basic testuser",
+            "HTTP_HOST": "petstore.swagger.io",
+        }
+        from django.conf import settings
+
+        MIDDLEWARE = [
+            v for v in settings.MIDDLEWARE if "openapi_core" not in v
+        ]
+        with override_settings(MIDDLEWARE=MIDDLEWARE):
+            response = client.post(
+                "/status", data=data, content_type=content_type, **headers
+            )
+
+        assert response.status_code == 405  # Method Not Allowed