Add streaming support for Next.js App Router

README.md

@@ -161,6 +161,25 @@ async def jobs(request):
     return await render_nextjs_page(request)
 ```
 
+#### Using `nextjs_page` with `stream=True` (Recommended)
+
+If you're using the [Next.js App Router](https://nextjs.org/docs/app) (introduced in Next.js 13+), you can enable streaming by setting the `stream=True` parameter in the `nextjs_page` function. This allows the HTML response to be streamed directly from the Next.js server to the client. This approach is particularly useful for server-side rendering with streaming support to show an [instant loading state](https://nextjs.org/docs/app/building-your-application/routing/loading-ui-and-streaming#instant-loading-states) from the Next.js server while the content of a route segment loads.
+
+Here's an example:
+
+```python
+from django_nextjs.views import nextjs_page
+
+urlpatterns = [
+  path("/nextjs/page", nextjs_page(stream=True), name="nextjs_page"),
+]
+```
+
+**Considerations:**
+
+- When using `stream_nextjs_page`, you cannot use a custom HTML template in Django, as the HTML is streamed directly from the Next.js server.
+- The `stream` parameter will default to `True` in future releases. Currently, it is set to `False` for backward compatibility. To avoid breaking changes, we recommend explicitly setting `stream=False` if you are customizing HTML and do not want to use streaming.
+
 ## Customizing the HTML Response
 
 You can modify the HTML code that Next.js returns in your Django code.

django_nextjs/render.py

@@ -5,7 +5,7 @@
 import aiohttp
 from asgiref.sync import sync_to_async
 from django.conf import settings
-from django.http import HttpRequest, HttpResponse
+from django.http import HttpRequest, HttpResponse, StreamingHttpResponse
 from django.middleware.csrf import get_token as get_csrf_token
 from django.template.loader import render_to_string
 from multidict import MultiMapping
@@ -70,14 +70,20 @@ def _get_nextjs_request_headers(request: HttpRequest, headers: Union[Dict, None]
     }
 
 
-def _get_nextjs_response_headers(headers: MultiMapping[str]) -> Dict:
+def _get_nextjs_response_headers(headers: MultiMapping[str], stream: bool = False) -> Dict:
     return filter_mapping_obj(
         headers,
         selected_keys=[
             "Location",
             "Vary",
             "Content-Type",
             "Set-Cookie",
+            "Link",
+            "Cache-Control",
+            "Connection",
+            "Date",
+            "Keep-Alive",
+            *(["Transfer-Encoding"] if stream else []),
         ],
     )
 
@@ -150,3 +156,38 @@ async def render_nextjs_page(
         headers=headers,
     )
     return HttpResponse(content=content, status=status, headers=response_headers)
+
+
+async def stream_nextjs_page(
+    request: HttpRequest,
+    allow_redirects: bool = False,
+    headers: Union[Dict, None] = None,
+):
+    """
+    Stream a Next.js page response.
+    This function is used to stream the response from a Next.js server.
+    """
+    page_path = quote(request.path_info.lstrip("/"))
+    params = [(k, v) for k in request.GET.keys() for v in request.GET.getlist(k)]
+    next_url = f"{NEXTJS_SERVER_URL}/{page_path}"
+
+    session = aiohttp.ClientSession(
+        cookies=_get_nextjs_request_cookies(request),
+        headers=_get_nextjs_request_headers(request, headers),
+    )
+    nextjs_response = await session.get(next_url, params=params, allow_redirects=allow_redirects)
+    response_headers = _get_nextjs_response_headers(nextjs_response.headers, stream=True)
+
+    async def stream_nextjs_response():
+        try:
+            async for chunk in nextjs_response.content.iter_any():
+                yield chunk
+        finally:
+            await nextjs_response.release()
+            await session.close()
+
+    return StreamingHttpResponse(
+        stream_nextjs_response(),
+        status=nextjs_response.status,
+        headers=response_headers,
+    )

django_nextjs/views.py

@@ -1,17 +1,24 @@
 from typing import Dict, Union
 
-from .render import render_nextjs_page
+from .render import render_nextjs_page, stream_nextjs_page
 
 
 def nextjs_page(
     *,
+    stream: bool = False,
     template_name: str = "",
     context: Union[Dict, None] = None,
     using: Union[str, None] = None,
     allow_redirects: bool = False,
     headers: Union[Dict, None] = None,
 ):
+    if stream and (template_name or context or using):
+        raise ValueError("When 'stream' is set to True, you should not use 'template_name', 'context', or 'using'")
+
     async def view(request, *args, **kwargs):
+        if stream:
+            return await stream_nextjs_page(request=request, allow_redirects=allow_redirects, headers=headers)
+
         return await render_nextjs_page(
             request=request,
             template_name=template_name,