Django: row still displayed after being deleted - because of caching?

Question

I've written a Django app that uses DataTables. The problem is when I delete a row from the table it's still displayed in the table when running against nginx/gunicorn. However, it works correctly when I'm running against the Django test server. So if I start a server with this command line:

python manage.py runserver 192.168.0.1:8000

everything works fine. That is, I delete the row, the table refreshes, and the deleted row is not displayed.

This is a summary of the HTTP calls:

// An initial GET command to populate the table
GET /myapp/get_list (returns a list to display)

// I now select a row and delete it which causes this POST to fire
POST /myapp/delete (deletes a row from the list)

// After the POST the code automatically follows up with a GET to refresh the table
GET /myapp/get_list (returns a list to display)

The problem is when I use nginx/gunicorn the second GET call returns the same list as the first GET including the row that I know has been deleted from the backend database.

I'm not sure it's a caching problem either because this is the response header I get from the first GET:

Date    Fri, 23 Dec 2011 15:04:16 GMT
Last-Modified   Fri, 23 Dec 2011 15:04:16 GMT
Server  nginx/0.7.65
Vary    Cookie
Content-Type    application/javascript
Cache-Control   max-age=0
Expires Fri, 23 Dec 2011 15:04:16 GMT

Answer 1

The problem can be solved also by sending an added parameter to the server so that the browser doesn't cache the call. With jQuery you can simply use:

$.ajaxSetup({ cache: false});

Otherwise you must creat manually the parameter. Usually you create a timestamp

var nocache = new Date().getTime();
//send nocache as a parameter so that the browser thinks it's a new call

Answer 2

You can use Django's add_never_cache_headers or never_cache decorator to tell the browser not to cache given request. Documentation is here. I thinks it's cleaner solution than forcing the cache off in the javascript.

    from django.utils.cache import add_never_cache_headers

    def your_view(request):
        (...)
        add_never_cache_headers(response)
        return response

    from django.views.decorators.cache import never_cache

    @never_cache
    def your_other_view(request):
            (...)

Answer 3

try this

oTable.fnDeleteRow( anSelected, null, true );

and b.t.w what version of datatables do you use?

Answer 4

I fixed the problem by changing

GET /myapp/get_list

to

POST /myapp/get_list

After doing this, I no longer get a cached response.