django多对多字段的列表显示项目，如计数

Question

我想在Django admin list_display中显示每个项目的总喜欢。多对多字段与用户模型相关联。下面是我的代码

模型:

class Item(models.Model):
title = models.CharField(max_length=100)
description= RichTextField(blank=True, null=True)
main_image= models.ImageField(null=False, blank=False,upload_to='images/')
upload = models.FileField(upload_to ='uploads/')
date = models.DateTimeField(auto_now_add=True)
item_category = models.ForeignKey(Categories, default='Coding', on_delete=SET_DEFAULT)
item_tool = models.ForeignKey(Tools, default='XD', on_delete=SET_DEFAULT)
slug = models.SlugField(unique=True, blank=True, null=True) # new
author = models.ForeignKey(User, on_delete=models.CASCADE)
likes = models.ManyToManyField(User, related_name='post_likes')
def total_likes(self):
return self.likes.count()

Admin.py

from django.contrib import admin
from .models import Categories, Item, Tools
class ItemAdmin(admin.ModelAdmin):
list_display = ('title','author','item_category','date')
list_filter = ('item_category',)

admin.site.register(Categories)
admin.site.register(Item, ItemAdmin)
admin.site.register(Tools)

Answer 1

您可以在list_display中添加自定义显示，以返回喜欢的数量，如下所示:

class ItemAdmin(admin.ModelAdmin):
list_display = ('title','author','item_category','date','likes_count')
list_filter = ('item_category',)
def likes_count(self, obj):
return len(obj.likes.all())
likes_count.short_description = 'Likes'
def get_queryset(self, *args, **kwargs):
return super().get_queryset(*args, **kwargs).prefetch_related('likes')

请注意get_queryset的额外更改，以帮助使用prefetch_related来减少db命中。如果没有它，Item实例的每一行都将访问数据库以获得喜欢的数量。

:

另一种方法是用喜欢的总数来注释每个条目，像这样:

class ItemAdmin(admin.ModelAdmin):
list_display = ('title','author','item_category','date','likes_count')
list_filter = ('item_category',)
def likes_count(self, obj):
return obj.likes_count
likes_count.short_description = 'Likes'
likes_count.admin_order_field = 'likes_count'
def get_queryset(self, *args, **kwargs):
return super().get_queryset(*args, **kwargs).annotate(likes_count=Count('likes'))

这将支持通过使用admin_order_field按点赞数排序。