Django Cors Allow Access-Control-Allow-Headers

Question

I'm trying to make a simple API using Django. I have setup a django server, and then on my own html file I send requests using $.getJSON. So far it's been working using the django cors headers package.

Now I've been trying to send a request header to my django server, but I'm getting this error in the Chrome console:

Access to XMLHttpRequest at 'http://127.0.0.1:8000/api/?q=example+query' from origin 'http://localhost:63342' has been blocked by CORS policy: Request header field Example-Header is not allowed by Access-Control-Allow-Headers in preflight response.

I'm not sure what's the problem, I have django-cors setup correctly and I am able to make requests, I'm just not allowed to set request headers.

Setup:

INSTALLED_APPS = [
    ...
    'corsheaders',
]
MIDDLEWARE = [
    ...
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.common.CommonMiddleware',
    ...
]
CORS_ALLOWED_ORIGINS = [
    "http://localhost:63342"
]

<script>
   $.ajaxSetup({
      beforeSend: function(request) {
         request.setRequestHeader("Example-Header", 'Example-Value');
      },
   });
   $.getJSON("http://127.0.0.1:8000/api/?q=example+query", function (data) {
      console.log(data);
   });
</script>

@cache_page(60 * 60 * 24 * 7)
def ExampleAPI(request):
    if request.method == 'GET':
       print(request.headers['Example-Header']) # Print Header Value 
       print(request.GET.get('q')) # Print URL Query Parameter Value   
       return JsonResponse([{"Example-Response": "Example-Response-Value"}], safe=False) 

So what am I doing wrong? Does django-cors not support this? I tried looking it up but I could not find anything. Thanks.

Answer 1

From documentation for django-cors-headers on PyPI it looks like you need to set the CORS_ALLOW_HEADERS like so:

CORS_ALLOW_HEADERS = [
    ...
    "Example-Header",
    ...
]

https://pypi.org/project/django-cors-headers/

If you want to dive deeper into CORS here is a thorough documentation: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS