如何获取含关联Bookmark的BookmarkCategory数据并返回JSON

请求示例 #

GET -> localhost:8000/api/bookmarks

目标JSON格式（示例） #

{
  "python": {
    "title": "Python",
    "bookmarks": [
      {
        "title": "Python Documentation",
        "url": "https://docs.python.org"
      }
    ]
  },
  "javascript": {
    "title": "Javascript",
    "bookmarks": [
      {
        "title": "JavaScript Documentation",
        "url": "https://developer.mozilla.org/en-US/docs/Web/JavaScript"
      }
    ]
  }
}

模型定义 #

class BookmarkCategory(models.Model):
    title = models.CharField(max_length=255)


class Bookmark(models.Model):
    title = models.CharField(max_length=255)
    url = models.CharField(max_length=255)
    category = models.ManyToManyField(BookmarkCategory)

当前查询方式 #

from .models import BookmarkCategory

bookmarks = BookmarkCategory.objects.all()

实现方案 #

方法1：基于Django REST Framework实现 #

如果使用DRF，通过嵌套序列化器可以快速生成目标结构：

# serializers.py
from rest_framework import serializers
from .models import BookmarkCategory, Bookmark

class BookmarkSerializer(serializers.ModelSerializer):
    class Meta:
        model = Bookmark
        fields = ['title', 'url']

class BookmarkCategorySerializer(serializers.ModelSerializer):
    bookmarks = BookmarkSerializer(many=True, source='bookmark_set')
    
    class Meta:
        model = BookmarkCategory
        fields = ['title', 'bookmarks']

# views.py
from rest_framework.response import Response
from rest_framework.decorators import api_view
from .serializers import BookmarkCategorySerializer

@api_view(['GET'])
def bookmarks_list(request):
    # 使用prefetch_related避免N+1查询
    categories = BookmarkCategory.objects.prefetch_related('bookmark_set').all()
    serializer = BookmarkCategorySerializer(categories, many=True)
    # 转换为以分类标题小写为键的字典结构
    data = {item['title'].lower(): item for item in serializer.data}
    return Response(data)

方法2：手动构造数据（无DRF依赖） #

如果不使用DRF，直接遍历模型实例构造数据：

# views.py
from django.http import JsonResponse
from .models import BookmarkCategory

def bookmarks_list(request):
    categories = BookmarkCategory.objects.prefetch_related('bookmark_set').all()
    result = {}
    for category in categories:
        category_key = category.title.lower()
        bookmarks = []
        for bookmark in category.bookmark_set.all():
            bookmarks.append({
                'title': bookmark.title,
                'url': bookmark.url
            })
        result[category_key] = {
            'title': category.title,
            'bookmarks': bookmarks
        }
    return JsonResponse(result)

说明：

• prefetch_related('bookmark_set')用于预加载关联的书签数据，避免多次查询数据库
• 示例中将分类标题转为小写作为键，和目标格式匹配；若不需要可直接使用原标题作为键

内容的提问来源于stack exchange，提问作者nandesuka