MarietjeDjango/marietje/songs/admin.py

from django.contrib import admin
from django.urls import reverse
from django.utils.html import format_html

from .models import ReportNote, Song


class ReportNoteInline(admin.StackedInline):
    model = ReportNote
    extra = 0
    autocomplete_fields = ('user',)

@admin.register(Song)
class SongAdmin(admin.ModelAdmin):
    list_display = ('artist', 'title', 'user_name', 'reports')
    search_fields = ('artist', 'title', 'user__name')
    inlines = [ReportNoteInline]
    autocomplete_fields = ('user',)

    @staticmethod
    def reports(song):
        return ReportNote.objects.filter(song=song).count()

    @staticmethod
    def user_name(song):
        try:
            return song.user.name
        except AttributeError:
            return '<unknown>'

    @staticmethod
    def get_readonly_fields(request, obj=None):
        return [] if request.user.is_superuser else ['hash']

@admin.register(ReportNote)
class ReportNoteAdmin(admin.ModelAdmin):
    exclude = ('song',)
    list_display = ('song', 'note', 'user')
    search_fields = ('song__artist', 'song__title', 'user__name')
    autocomplete_fields = ('user',)
    readonly_fields = ('song_link',)

    @staticmethod
    def song_link(note):
        url = reverse("admin:songs_song_change", args=(note.song.id,))
        return format_html("<a href='{url}'>{song}</a>", url=url, song=note.song)

    song_link.short_description = "Song link"