如何在 django rest 框架中的分页 URL 中更改下一个键中的主机？

Question

I have a ModelSerializer in Django Rest Framework with paginated responses. So I have deployed it with gunicorn in a docker container.

gunicorn -c gunicorn_config.py app.wsgi --bind 0.0.0.0:5000

Now the problem is in the paginated responses. The next key is something like.

next: "http://0.0.0.0:5000/admin/users/?page=2&per_page=10"

In my client-side where I am consuming these APIs, I just check the next key and fetch the next response. But since the next key has the host as 0.0.0.0:5000 hence it will cause API call failure. And the purpose is not served for the next key.

So at the moment, my API server is running in a separate docker container. Which is set up via the reverse proxy in nginx .

Answer 1

The next link in the DRF paginator is generated using the hostname from the request. This is how the hostname is determined in the request:

def _get_raw_host(self):
    """
    Return the HTTP host using the environment or request headers. Skip
    allowed hosts protection, so may return an insecure host.
    """
    # We try three options, in order of decreasing preference.
    if settings.USE_X_FORWARDED_HOST and (
            'HTTP_X_FORWARDED_HOST' in self.META):
        host = self.META['HTTP_X_FORWARDED_HOST']
    elif 'HTTP_HOST' in self.META:
        host = self.META['HTTP_HOST']
    else:
        # Reconstruct the host using the algorithm from PEP 333.
        host = self.META['SERVER_NAME']
        server_port = self.get_port()
        if server_port != ('443' if self.is_secure() else '80'):
            host = '%s:%s' % (host, server_port)
    return host

So, check if the HTTP_X_FORWARDED_HOST header sets the correct hostname you need and if so set USE_X_FORWARDED_HOST to True in your settings. Also make sure that the hostname you need is added to ALLOWED_HOSTS .

You could also override the get_next_link() method in the PageNumberPagination class to supply the needed host/domain name

Answer 2

So I made a custom pagination class extending PageNumberPagination

from rest_framework.pagination import PageNumberPagination
def replace_query_param(url, key, val):
    """
    Given a URL and a key/val pair, set or replace an item in the query
    parameters of the URL, and return the new URL.
    """
    (scheme, netloc, path, query, fragment) = parse.urlsplit(force_str(url))
    scheme = "https"
    netloc = "api.example.com"
    query_dict = parse.parse_qs(query, keep_blank_values=True)
    query_dict[force_str(key)] = [force_str(val)]
    query = parse.urlencode(sorted(list(query_dict.items())), doseq=True)
    return parse.urlunsplit((scheme, netloc, path, query, fragment))


def remove_query_param(url, key):
    """
    Given a URL and a key/val pair, remove an item in the query
    parameters of the URL, and return the new URL.
    """
    (scheme, netloc, path, query, fragment) = parse.urlsplit(force_str(url))
    scheme = "https"
    netloc = "api.example.com"
    query_dict = parse.parse_qs(query, keep_blank_values=True)
    query_dict.pop(key, None)
    query = parse.urlencode(sorted(list(query_dict.items())), doseq=True)
    return parse.urlunsplit((scheme, netloc, path, query, fragment))

class LargeResultsSetPagination(PageNumberPagination):
    page_size = 1000
    page_size_query_param = 'per_page'
    max_page_size = 1000

    def get_next_link(self):
        if not self.page.has_next():
            return None
        url = self.request.build_absolute_uri()
        page_number = self.page.next_page_number()
        return replace_query_param(url, self.page_query_param, page_number)

    def get_previous_link(self):
        if not self.page.has_previous():
            return None
        url = self.request.build_absolute_uri()
        page_number = self.page.previous_page_number()
        if page_number == 1:
            return remove_query_param(url, self.page_query_param)
        return replace_query_param(url, self.page_query_param, page_number)

Now I am using this pagination class in all my ViewSets

class TestViewSet(viewsets.ModelViewSet):
    permission_classes = [permissions.IsAuthenticated]

    queryset = Test.objects.all().order_by("pk")
    serializer_class = test_serializers.TestSerializer
    pagination_class = LargeResultsSetPagination
    search_fields = ['name', 'description', 'follow_up', 'follow_up_type']
    filter_backends = (filters.SearchFilter,)

And it does the job, the original inspiration https://stackoverflow.com/a/62422235/5884045