old_contents: from django.contrib import admin
  
  from schedule.forms import EventAdminForm
  from schedule.models import Calendar, CalendarRelation, Event, Occurrence, Rule
  
  
  @admin.register(Calendar)
  class CalendarAdmin(admin.ModelAdmin):
      list_display = ("name", "slug")
      prepopulated_fields = {"slug": ("name",)}
      search_fields = ["name"]
      fieldsets = ((None, {"fields": [("name", "slug")]}),)
  
  
  @admin.register(CalendarRelation)
  class CalendarRelationAdmin(admin.ModelAdmin):
      list_display = ("calendar", "content_object")
      list_filter = ("inheritable",)
      fieldsets = (
          (
              None,
              {
                  "fields": [
                      "calendar",
                      ("content_type", "object_id", "distinction"),
                      "inheritable",
                  ]
              },
          ),
      )
  
  
  @admin.register(Event)
  class EventAdmin(admin.ModelAdmin):
      list_display = ("title", "start", "end")
      list_filter = ("start",)
      ordering = ("-start",)
      date_hierarchy = "start"
      search_fields = ("title", "description")
      fieldsets = (
          (
              None,
              {
                  "fields": [
                      ("title", "color_event"),
                      ("description",),
                      ("start", "end"),
                      ("creator", "calendar"),
                      ("rule", "end_recurring_period"),
                  ]
              },
          ),
      )
      form = EventAdminForm
  
  
  admin.site.register(Occurrence, admin.ModelAdmin)
  
  
  @admin.register(Rule)
  class RuleAdmin(admin.ModelAdmin):
      list_display = ("name",)
      list_filter = ("frequency",)
      search_fields = ("name", "description")
  
new_contents: from django.contrib import admin
  
  from schedule.forms import EventAdminForm
  from schedule.models import (
      Calendar,
      CalendarRelation,
      Event,
      EventRelation,
      Occurrence,
      Rule,
  )
  
  
  @admin.register(Calendar)
  class CalendarAdmin(admin.ModelAdmin):
      list_display = ("name", "slug")
      prepopulated_fields = {"slug": ("name",)}
      search_fields = ["name"]
      fieldsets = ((None, {"fields": [("name", "slug")]}),)
  
  
  @admin.register(CalendarRelation)
  class CalendarRelationAdmin(admin.ModelAdmin):
      list_display = ("calendar", "content_object")
      list_filter = ("inheritable",)
      fieldsets = (
          (
              None,
              {
                  "fields": [
                      "calendar",
                      ("content_type", "object_id", "distinction"),
                      "inheritable",
                  ]
              },
          ),
      )
  
  
  @admin.register(EventRelation)
  class EventRelationAdmin(admin.ModelAdmin):
      list_display = ("event", "content_object", "distinction")
      fieldsets = (
          (None, {"fields": ["event", ("content_type", "object_id", "distinction")]}),
      )
  
  
  @admin.register(Event)
  class EventAdmin(admin.ModelAdmin):
      list_display = ("title", "start", "end")
      list_filter = ("start",)
      ordering = ("-start",)
      date_hierarchy = "start"
      search_fields = ("title", "description")
      fieldsets = (
          (
              None,
              {
                  "fields": [
                      ("title", "color_event"),
                      ("description",),
                      ("start", "end"),
                      ("creator", "calendar"),
                      ("rule", "end_recurring_period"),
                  ]
              },
          ),
      )
      form = EventAdminForm
  
  
  admin.site.register(Occurrence, admin.ModelAdmin)
  
  
  @admin.register(Rule)
  class RuleAdmin(admin.ModelAdmin):
      list_display = ("name",)
      list_filter = ("frequency",)
      search_fields = ("name", "description")
  
subject: Add EventRelation to Django admin (#474)