django - DRF如何获取按类别分组的项目

Question

我知道我的问题经常被重复，但我坚持这一点。
我想用 DRF 制作简单的 api。我有两个模型:

models.py

class Rubrics(models.Model):
    id = models.AutoField(primary_key=True)
    rubric = models.CharField(max_length=255, blank=True, null=True)

class Books(models.Model):
    id = models.AutoField(primary_key=True)
    title = models.CharField(max_length=255, blank=True, null=True)
    author = models.CharField(max_length=255, blank=True, null=True)
    date = models.CharField(max_length=255, blank=True, null=True)
    rubrics = models.ForeignKey('Rubrics', on_delete=models.DO_NOTHING, related_name='books', blank=True, null=True)

我想像这样查看序列化结果:

[
    rubric1: [
        {
         title: "title1",
         author:"author1"
        }, 
        book_obj2,
        so on
    ],
    rubric2: [
        book_obj4,
        book_obj5
    ]
]

我的意见.py:

class BooksByRubricView(APIView):
    """List of books by rubrics"""

    def get(self, request):
        last_date = Books.objects.latest("date").date
        books_last = Books.objects.filter(date=last_date)
        serializer = RubricsSerializer(books_last, many=True)
        return Response(serializer.data)

我在这个主题中尝试了很多例子，

sorry this garbage
class BookSerializer(serializers.ModelSerializer):
    class Meta:
        model = Books
        #fields = ("title",)
        exclude = ()

class RubricsSerializer(serializers.ModelSerializer):
    rubrics = BookSerializer(read_only=True)
    class Meta:
        model = Rubrics
        fields = ("rubrics",)
        #exclude = ()
"""
class RubricSerializer(serializers.ModelSerializer):
    #rubrics = serializers.PrimaryKeyRelatedField(many=True, read_only=True)
    #books = RecursiveSerializer(many=True)
    #print(books)
    rubrics = RubricSerializer(read_only=True)
    #books = BooksListSerializer(many=True)
    class Meta:
        model = Books
        fields  = ("title", "rubrics",)
        #fields = ['rubric', 'rubrics']
        #fields = ['books', 'rubrics']
"""

但也许我不了解 DRF 中反向关系和序列化的原则。请告诉我WAIDW。谢谢。
更新。
我只想对指定的数据集进行操作(例如，处理最后上传的书籍)，而不是对整个表 Books 进行操作。所以我只想查看这个集合中的评分细则，而不是表格评分细则中的所有评分细则。是的，书籍在指定字段中只有一个 rubric id，并且 rubric 与书籍是一对多的关系。
嗯，这就是我想看到的 json(当然，这部作品中出现的所有角色都是虚构的。任何与真实人物、生者或死者的相似之处纯属巧合。):

{
    "rubric1": [{
        "author": "Marley W. Watkins",
        "title": "A Step-By-Step Guide to Exploratory Factor Analysis with Stata"
    }, {
        "author": "Robert E. Davis",
        "title": "Auditing Information and Cyber Security Governance; A Controls-Based Approach"
    }, {
        "author": "Gerhard X. Ritter, Gonzalo Urcid",
        "title": "Introduction to Lattice Algebra: With Applications in AI, Pattern Recognition, Image Analysis, and Biomimetic Neural Networks"
    }],
    "rubric2": [{
        "author": "Richard Cross and JT Paasch",
        "title": "The Routledge Companion to Medieval Philosophy"
    }, {
        "author": "Nicholas Allott (editor), Terje Lohndal (editor), Georges Rey (editor)",
        "title": "A Companion to Chomsky"
    }, {
        "author": "Olakunle George",
        "title": "A Companion to African Literatures"
    }, {
        "author": "Tim Byrnes, Ebubechukwu O. Ilo-Okeke",
        "title": "Quantum Atom Optics: Theory and Applications to Quantum Technology"
    }],
    "rubric3": [{
        "author": "Hiroyoshi Naito",
        "title": "Organic Semiconductors for Optoelectronics"
    }, {
        "author": "Bassem R. Mahafza, Scott C. Winton",
        "title": "Handbook of Radar Signal Analysis"
    }, {
        "author": "Sean McManus, Mike Cook",
        "title": "Raspberry Pi For Dummies, 4th Edition"
    }]
}

我在“普通”django中意识到:

class BooksByRubricView(APIView):
    """List of books by rubrics"""

    def get(self, request):
        last_date = Books.objects.using('books').latest("date").date
        books_last = Books.objects.using('books').filter(date=last_date)

        categories = []
        res_dict = {}

        for item in books_last:
            categories.append(item.rubrics_id)

        categories = set(categories)
        
        for item in categories:
            temp_list = []
            temp_qs = books_last.filter(rubrics_id=item)
            for i in temp_qs:
                temp_list.append({"author": i["author"], "title": i["title"]})
            
            res_dict["rubric"+str(item)]=list(temp_list)

        # res = json.dumps(res_dict)
        return JsonResponse(res_dict, safe=False, json_dumps_params={'ensure_ascii': False})

我可以用 drf 序列化器来实现它，或者最简单的方法是不费脑筋并返回 json 如上所述？
UPD2。
好吧，在使用序列化程序和 generic.APIView 进行一些魔术之后，我得到的结果并不完全符合预期，但非常接近。例子(当然，本作品中出现的所有人物都是虚构的。任何与真实人物，生者或死者的相似之处，纯属巧合)

views.py
class BooksByRubricView2(generics.ListAPIView):
    """Books grouped by rubrics"""
    serializer_class = RubricsSerializer2
    queryset = Rubrics.objects.all()

#OR without generic
class BooksByRubricView3(APIView):

    def get(self, request):
        r = Rubrics.objects.all()
        serializer=RubricsSerializer2(r,many=True)
        return Response(serializer.data)

serializers.py
class FilteredListSerializer(serializers.ListSerializer):
    """Serializer to filter Book table, look for latest date for every rubric"""

    def to_representation(self, data):
        latest_data = data.latest("date").date
        data = data.filter(date=latest_data)
        return super(FilteredListSerializer, self).to_representation(data)


class BookSerializer2(serializers.ModelSerializer):
    class Meta:
        model = Books
        list_serializer_class = FilteredListSerializer
        fields = (
            "title",
            "author",
            "date")


class RubricsSerializer2(serializers.ModelSerializer):
    books = BookSerializer2(many=True, read_only=True)
    class Meta:
        model = Rubrics
        fields = ("rubric", "books",)

result:
[
    {
        "rubric": "Computers",
        "books": [
            {
                "title": "A Step-By-Step Guide to Exploratory Factor Analysis with Stata",
                "author": "Marley W. Watkins",
                "date": "2021-08-08"
            },
            {
                "title": "Auditing Information and Cyber Security Governance; A Controls-Based Approach",
                "author": "Robert E. Davis",
                "date": "2021-08-08"
            }
        ]
    },
    {
        "rubric": "Education",
        "books": [
            {
                "title": "The Routledge Companion to Medieval Philosophy",
                "author": "Richard Cross and JT Paasch",
                "date": "2021-08-08"
            }
        ]
    },
    so on
}

这是一种肮脏的方式，因为表 Rubrics 中的每个 Rubric 都会创建自己对表 Books 的查询，并且每个 Rubric 都有自己的最新日期。但 DRF 过滤将是下一步... =)
谢谢大家，“我会回来的”

Answer 1

没有字段rubrics在 Rubrics模型，可用字段有:

id , rubric来自模型本身，

books_set代表所有具有 FK 引用的书籍 Rubrics实例。看看this official docs

一本书有一个rubric(rubrics外键)，rubric有多本书(books_set)。我还建议从 rubrics 更改 FK 名称至 rubric因为只能有一个。
试试这个并从那里开始工作:

class BookSerializer(serializers.ModelSerializer):
    class Meta:
        model = Books
        #fields = ("title",)
        exclude = ()

class RubricsSerializer(serializers.ModelSerializer):
    class Meta:
        model = Rubrics
        fields = ("books_set",)
        #exclude = ()