Django admin change_list view get ChangeList queryset - better solution than my monkey patch

Question

I need to get a changelist view queryset in django admin. Currently, I have this monkey patch which makes 4 extra queries, so I'm looking for a better solution.

My point is: I want to pass some extra values to django admin change_list.html template which I get from creating queries. For those queries, I need the queryset which is used in django admin changelist view with request filters applied. This is the same data which I see filtered, ordered etc. I want to make graphs from this data.

Do you understand me? Thanks

#admin.py
from django.contrib.admin.views.main import ChangeList

class TicketAdmin(admin.ModelAdmin):

    def changelist_view(self, request, extra_context=None):

        cl = ChangeList(request, 
                        self.model, 
                        self.list_display, 
                        self.list_display_links, 
                        self.list_filter, 
                        self.date_hierarchy, 
                        self.search_fields, 
                        self.list_select_related, 
                        self.list_per_page,
                        self.list_max_show_all, 
                        self.list_editable, 
                        self) # 3 extra queries
        filtered_query_set = cl.get_query_set(request) # 1 extra query

        currencies_count = filtered_query_set.values('bookmaker__currency').distinct().count()

        extra_context = {
            'currencies_count': currencies_count,
        }
        return super(TicketAdmin, self).changelist_view(request, extra_context=extra_context)

Answer 1

I don't know if this answers to your question but the class ChangeList has an attribute called query_set (you can find the code here https://github.com/django/django/blob/master/django/contrib/admin/views/main.py) already containing the queryset.

BTW the changelist_view() function (source at https://github.com/django/django/blob/master/django/contrib/admin/options.py) returns a TemplateResponse (source at https://github.com/django/django/blob/master/django/template/response.py) that has a variable named context_data which points to the context. You can try to extend the content of this variable.

Below follows the untested code

class TicketAdmin(admin.ModelAdmin):

    def changelist_view(self, request, extra_context=None):
        response = super(TicketAdmin, self).changelist_view(request, extra_context)
        filtered_query_set = response.context_data["cl"].queryset

        currencies_count = filtered_query_set.values('bookmaker__currency').distinct().count()
        extra_context = {
             'currencies_count': currencies_count,
        }
        response.context_data.update(extra_context)

        return response