old_contents: from models import Achievement, Category, CollectionAchievement, Progress, ProgressAchievement, Task, TaskAchievement, TaskProgress, Trophies, UserAchievement
  from django.contrib import admin
  from django.contrib.admin.widgets import FilteredSelectMultiple
  from django.db import models
  
  class CategoryAdmin(admin.ModelAdmin):
      list_display=['name', 'parent_category']
      search_fields = ('name', 'parent_category')
  
new_contents: from models import Achievement, Category, CollectionAchievement, Progress, ProgressAchievement, Task, TaskAchievement, TaskProgress, Trophies, UserAchievement
  from django.contrib import admin
  from django.contrib.admin.widgets import FilteredSelectMultiple
  from django.db import models
  
  class CategoryAdmin(admin.ModelAdmin):
      list_display=['name', 'parent_category']
      search_fields = ('name', 'parent_category')
  
  class AchievementAdmin(admin.ModelAdmin):
      list_display=['name', 'description', 'category']
      search_fields = ('name', 'category')
  
subject: add class AchievementAdmin