How to filter and paginate in ListView Django

Question

I have a problem when I want to paginate the filter that I create with django_filter, in my template it shows me the query set and filter but paginate does not work, I would like to know why this happens and if you could help me.

I'll insert snippets of my code so you can see.

This is my views.py

PD: i have all the necesary imports.

@method_decorator(staff_member_required, name='dispatch')
class EmployeeListView(ListView):
    model = Employee
    paginate_by = 4

    def dispatch(self, request, *args, **kwargs):
        if not request.user.has_perm('employee.view_employee'):
            return redirect(reverse_lazy('home'))
        return super(EmployeeListView, self).dispatch(request, *args, **kwargs)
    
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['filter'] = EmployeeFilter(self.request.GET, queryset = self.get_queryset())
        return context

filters.py

import django_filters
from .models import Employee, Accident

class EmployeeFilter(django_filters.FilterSet):

    class Meta:
        model = Employee
        fields = {
            'rutEmployee' : ['startswith']
        }

Nook

Answer 1

You should override get_queryset.This means you have to put your filter in get_queryset like this:

@method_decorator(staff_member_required, name='dispatch')
class EmployeeListView(ListView):
    model = Employee
    paginate_by = 4

    def dispatch(self, request, *args, **kwargs):
        if not request.user.has_perm('employee.view_employee'):
            return redirect(reverse_lazy('home'))
        return super(EmployeeListView, self).dispatch(request, *args, **kwargs)

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['filter'] = EmployeeFilter(self.request.GET, queryset = self.get_queryset())
        return context
    
    def get_queryset(self):
        queryset = super().get_queryset()
        return EmployeeFilter(self.request.GET, queryset=queryset).qs

and use object_list instead of filter in employee_list.html like this:

{% for employee in object_list|dictsort:"id" reversed %}

Grainfield

Hi thanks for your help, apply the changes you suggest but it gives me the following error: TypeError at /employee/ filter_queryset() got multiple values for argument 'queryset' in this line: return EmployeeFilter().filter_queryset(self.request.GET, queryset=queryset) – Nook

hi, i just applied the changes and it throws me the following: filter_queryset() takes 2 positional arguments but 4 were given – Nook

I thought you used rest filters. Sorry for the mistake. Please try again with the new changes – Grainfield

Thank you very much friend, it served me perfectly, would you mind giving me an explanation of why it works now with the function of get_queryset? – Nook

If you see get_context_data method of MultipleObjectMixin in github.com/django/django/blob/master/django/views/generic/… you know how queryset is paginated. Each time you use ListView, object_list is the paginated queryset, so if you filter queryset by overriding get_queryset, object_list will be filtered. – Grainfield

I understand, thank you very much for the help and the explanation, greetings from Chile. – Nook

This answer is like gold for figuring out how to combine FilterView and ListView. Thank you – Souther

Answer 2

You could also try this: (A snippet from my source code)

class ModelListView(ListView):
    model = YourModel
    paginate_by = 4 # Change this if you don't intend to paginate by 4
    ordering = model_field_to_order_by
    # variable used to know if a match was found for the search made using django_filters
    no_search_result = False

    def get_queryset(self, **kwargs):
        search_results = YourDjangoFiltersForm(self.request.GET, self.queryset)
        self.no_search_result = True if not search_results.qs else False
        # Returns the default queryset if an empty queryset is returned by the django_filters
        # You could as well return just the search result's queryset if you want to
        return search_results.qs.distinct() or self.model.objects.all()

    def get_query_string(self):
        query_string = self.request.META.get("QUERY_STRING", "")
        # Get all queries excluding pages from the request's meta
        validated_query_string = "&".join([x for x in re.findall(
            r"(\w*=\w{1,})", query_string) if not "page=" in x])
        # Avoid passing the query path to template if no search result is found using the previous query
        return "&" + validated_query_string.lower() if (validated_query_string and not self.no_search_result) else ""

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # Pass to template if you want to do something whenever an empty queryset is return by django_filters
        context["no_search_result"] = self.no_search_result
        # This is the query string which should be appended to the current page in your template for pagination, very critical
        context["query_string"] = self.get_query_string()
        context['filter'] = YourDjangoFiltersForm()
        return context

In your html template you need to append the querystring passed to your template from the view, a sample is shown below

{% for i in page_obj.paginator.page_range %}
    {% if page_obj.number == i %}
          <li class="page-item active" aria-current="page">
            <span class="page-link">{{ i }}<span class="sr-only">(current)</span></span>
          </li>
          {% elif i > page_obj.number|add:'-5' and i < page_obj.number|add:'5' %} <li class="page-item"><a
              class="page-link" href="?page={{ i }}{{ query_string }}">{{ i }}</a></li>
    {% endif %}
{% endfor %}

Octavia