SSE

Backend half of SSE (there is also frontend part)

Properties: SSE Backend Pieces

• HTMX SSE extension in /static/js/

• ASGI

• Nginx config:

  server {
    listen 80;
    location / {
        proxy_pass http://django:8000;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
  
        proxy_buffering off;
        proxy_cache off;
  
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
  
        proxy_read_timeout 86400s;
        proxy_send_timeout 86400s;
    }
  }
  

• View:

    import asyncio
    from django.http import StreamingHttpResponse
    from django.template.loader import render_to_string
  
    async def book_stream(request):
        """
        Asynchronously streams book updates as Server-Sent Events (SSE).
        """
        async def event_stream():
            while True:
                # 1. Fetch or generate updated data
                # (Use sync_to_async if querying the database)
                books = await get_latest_books_async() 
                
                # 2. Render a partial HTML template for the table rows
                html = render_to_string('partials/book_rows.html', {'books': books})
                
                # 3. Format the data for SSE (must start with 'data: ' and end with '\n\n')
                # HTMX will swap the content inside the 'data' field into your table
                yield f"data: {html}\n\n"
                
                # 4. Wait before the next update (e.g., 3 seconds)
                await asyncio.sleep(3)
  
        return StreamingHttpResponse(event_stream(), content_type='text/event-stream')
  

• Url: path('sse/', sse.book_stream, name='sse')

Workflow: How to add SSE to the app?

1. Make sure the project is ASGI-powered.

2. Make sure Nginx is configured for SSE

3. Write the view that returns StreamingHttpResponse

4. Make sure the view is in urlconfig

Workflow: How to write the view that returns StreamingHttpResponse?

1. Copy the minimal example view above.

2. Rewrite it keeping

   while True:
       ...
       await asyncio.sleep()