old_contents: from django.contrib import admin
  
  from event_store.models import Event
  
  @admin.register(Event)
  class EventAdmin(admin.ModelAdmin):
      list_display = ('title',
                      'organization_status_review',
                      'organization_status_prep',
                      'status',
                      'organization_host',
                      'notes')
      list_filter = ('organization_status_review',
                     'organization_status_prep',
                     'organization_campaign',
                     # US district
                     'state',
                     'is_private',
                     'starts_at',
                     'ends_at',
                     'attendee_count',
                     # event fields
                     'status',
                     'host_is_confirmed'
                     # sorting
                     )
  
new_contents: from django.contrib import admin
  from django import forms
  
  from event_store.models import Event
  from huerta.filters import CollapsedListFilter
  
  @admin.register(Event)
  class EventAdmin(admin.ModelAdmin):
      list_display = ('title',
                      'organization_status_review',
                      'organization_status_prep',
                      'status',
                      'organization_host',
                      'notes')
      list_filter = (('organization_status_review', CollapsedListFilter),
                     ('organization_status_prep', CollapsedListFilter),
                     ('organization_campaign', CollapsedListFilter),
                     ('state', CollapsedListFilter),
                     ('is_private', CollapsedListFilter),
                     ('starts_at', CollapsedListFilter),
                     ('ends_at', CollapsedListFilter),
                     ('attendee_count', CollapsedListFilter),
                     ('status', CollapsedListFilter),
                     ('host_is_confirmed', CollapsedListFilter))
      list_display_links = None
  
subject: change filters to CollapsedListFilter type