set status code in middleware

docs/source/form-submission.md

@@ -0,0 +1,15 @@
+# Form Submission
+
+By default, Turbo will intercept all clicks on links and form submission, as for form submission, if the form validation fail on the server side, Turbo expects the server return `422 Unprocessable Entity`.
+
+In Django, however, failed form submission would still return HTTP `200`, which would cause some issues when working with Turbo Drive.
+
+[https://turbo.hotwired.dev/handbook/drive#redirecting-after-a-form-submission](https://turbo.hotwired.dev/handbook/drive#redirecting-after-a-form-submission)
+
+How to solve this issue?
+
+`turbo_helper.middleware.TurboMiddleware` can detect POST request from Turbo and change the response status code to `422` if the form validation failed.
+
+It should work out of the box for `Turbo 8+` on the frontend.
+
+So developers do not need to manually set the status code to `422` in the view.

docs/source/index.rst

@@ -17,12 +17,12 @@ Topics
    :maxdepth: 2
 
    install.md
+   form-submission.md
    dom_id.md
    turbo_frame.md
    turbo_stream.md
    real-time-updates.md
    extend-turbo-stream.md
    multi-format.md
    signal-decorator.md
-   redirect.md
    test.md

docs/source/install.md

@@ -37,7 +37,7 @@ MIDDLEWARE = [
 ]
 ```
 
-With the `TurboMiddleware` we have `request.turbo` object which we can access in Django view or template.
+With the `TurboMiddleware` we have `request.turbo` object which we can access in Django view or template. It will also help us to change the response status code to `422` if the POST request come from Turbo and the form validation failed.
 
 If the request originates from a turbo-frame, we can get the value from the `request.turbo.frame`
 

src/turbo_helper/middleware.py

@@ -1,3 +1,4 @@
+import http
 import threading
 from typing import Callable
 
@@ -53,9 +54,13 @@ def __bool__(self):
 
 
 class TurboMiddleware:
-    """Adds `turbo` attribute to request:
+    """
+    Task 1: Adds `turbo` attribute to request:
     1. `request.turbo` : True if request contains turbo header
     2. `request.turbo.frame`: DOM ID of requested Turbo-Frame (or None)
+
+    Task 2: Auto change status code for Turbo Drive
+    https://turbo.hotwired.dev/handbook/drive#redirecting-after-a-form-submission
     """
 
     def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
@@ -64,5 +69,21 @@ def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
     def __call__(self, request: HttpRequest) -> HttpResponse:
         with SetCurrentRequest(request):
             request.turbo = SimpleLazyObject(lambda: TurboData(request))
+
             response = self.get_response(request)
+
+            if (
+                request.method == "POST"
+                and request.headers.get("X-Turbo-Request-Id")
+                and response.get("Content-Type") != "text/vnd.turbo-stream.html"
+            ):
+                if response.status_code == http.HTTPStatus.OK:
+                    response.status_code = http.HTTPStatus.UNPROCESSABLE_ENTITY
+
+                if response.status_code in (
+                    http.HTTPStatus.MOVED_PERMANENTLY,
+                    http.HTTPStatus.FOUND,
+                ):
+                    response.status_code = http.HTTPStatus.SEE_OTHER
+
         return response

tests/test_middleware.py

@@ -1,7 +1,14 @@
+import http
+
 import pytest
-from django.http import HttpResponse
+from django.http import (
+    HttpResponse,
+    HttpResponsePermanentRedirect,
+    HttpResponseRedirect,
+)
 
 from turbo_helper.middleware import TurboMiddleware
+from turbo_helper.response import TurboStreamResponse
 
 
 @pytest.fixture
@@ -11,23 +18,94 @@ def get_response():
 
 class TestTurboMiddleware:
     def test_accept_header_not_found(self, rf, get_response):
-        req = rf.get("/", HTTP_ACCEPT="text/html")
+        headers = {
+            "ACCEPT": "text/html",
+        }
+        headers = {f"HTTP_{key.upper()}": value for key, value in headers.items()}
+        req = rf.get("/", **headers)
         TurboMiddleware(get_response)(req)
         assert not req.turbo
         assert req.turbo.frame is None
 
     def test_accept_header_found(self, rf, get_response):
-        req = rf.get("/", HTTP_ACCEPT="text/vnd.turbo-stream.html")
+        headers = {
+            "ACCEPT": "text/vnd.turbo-stream.html",
+        }
+        headers = {f"HTTP_{key.upper()}": value for key, value in headers.items()}
+        req = rf.get("/", **headers)
         TurboMiddleware(get_response)(req)
         assert req.turbo
         assert req.turbo.frame is None
 
     def test_turbo_frame(self, rf, get_response):
-        req = rf.get(
-            "/",
-            HTTP_ACCEPT="text/vnd.turbo-stream.html",
-            HTTP_TURBO_FRAME="my-playlist",
-        )
+        headers = {
+            "ACCEPT": "text/vnd.turbo-stream.html",
+            "TURBO_FRAME": "my-playlist",
+        }
+        headers = {
+            f"HTTP_{key.upper()}": value for key, value in headers.items()
+        }  # Add "HTTP_" prefix
+        req = rf.get("/", **headers)
         TurboMiddleware(get_response)(req)
         assert req.turbo
         assert req.turbo.frame == "my-playlist"
+
+
+class TestTurboMiddlewareAutoChangeStatusCode:
+    def test_post_failed_form_submission(self, rf):
+        headers = {
+            "ACCEPT": "text/vnd.turbo-stream.html",
+            "X-Turbo-Request-Id": "d4165765-488b-41a0-82b6-39126c40e3e0",
+        }
+        headers = {
+            f"HTTP_{key.upper()}": value for key, value in headers.items()
+        }  # Add "HTTP_" prefix
+        req = rf.post("/", **headers)
+
+        def form_submission(request):
+            # in Django, failed form submission will return 200
+            return HttpResponse()
+
+        resp = TurboMiddleware(form_submission)(req)
+
+        assert resp.status_code == http.HTTPStatus.UNPROCESSABLE_ENTITY
+
+    @pytest.mark.parametrize(
+        "response_class", [HttpResponseRedirect, HttpResponsePermanentRedirect]
+    )
+    def test_post_succeed_form_submission(self, rf, response_class):
+        headers = {
+            "ACCEPT": "text/vnd.turbo-stream.html",
+            "X-Turbo-Request-Id": "d4165765-488b-41a0-82b6-39126c40e3e0",
+        }
+        headers = {
+            f"HTTP_{key.upper()}": value for key, value in headers.items()
+        }  # Add "HTTP_" prefix
+        req = rf.post("/", **headers)
+
+        def form_submission(request):
+            # in Django, failed form submission will return 301, 302
+            return response_class("/success/")
+
+        resp = TurboMiddleware(form_submission)(req)
+
+        assert resp.status_code == http.HTTPStatus.SEE_OTHER
+
+    def test_post_turbo_stream(self, rf, get_response):
+        """
+        Do not change if response is TurboStreamResponse
+        """
+        headers = {
+            "ACCEPT": "text/vnd.turbo-stream.html",
+            "X-Turbo-Request-Id": "d4165765-488b-41a0-82b6-39126c40e3e0",
+        }
+        headers = {
+            f"HTTP_{key.upper()}": value for key, value in headers.items()
+        }  # Add "HTTP_" prefix
+        req = rf.post("/", **headers)
+
+        def form_submission(request):
+            return TurboStreamResponse()
+
+        resp = TurboMiddleware(form_submission)(req)
+        assert resp.status_code == http.HTTPStatus.OK