DRF ListSerializer和ListField

Question

我在我的项目中使用django rest，直到现在我使用了ListSerializer的对象列表，当我需要搜索并到达ListField的列表的最小长度和最大长度时。

在此之前，我的代码被罚款，没有任何错误和不当行为。现在我使用ListField作为列表字段序列化程序，但是我没有得到什么时候使用ListSerializer？有人能解释一下ListSerializer和FieldSerializer之间的区别吗？

我用ListSerializer编写的示例代码：

tags = serializers.ListSerializer(child=serializers.CharField(allow_blank=False), required=False)

我用ListField编写的示例代码：

open_hour = serializers.ListField(child=serializers.DictField(), max_length=7, min_length=7)

Answer 1

免责声明：此答案不完整

有人能解释一下ListSerializer和FieldSerializer之间的区别吗？

我想问题是 serializers.ListSerializer 和 serializers.ListField之间的区别

假设我们有两个models作为

class Musician(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    instrument = models.CharField(max_length=100)

    def __str__(self):
        return f'{self.first_name} {self.last_name}'


class Album(models.Model):
    artist = models.ForeignKey(Musician, on_delete=models.CASCADE)
    name = models.CharField(max_length=100)
    release_date = models.DateField()
    num_stars = models.IntegerField()

    def __str__(self):
        return f'{self.name} : {self.artist}'

和serializer作为

class AlbumSerializer(serializers.ModelSerializer):
    artist = serializers.StringRelatedField()

    class Meta:
        fields = '__all__'
        model = Album


class MusicianSerializer(serializers.ModelSerializer):
    AlbumSerializer(many=True, source='album_set')

    class Meta:
        fields = '__all__'
        model = Musician

ListSerializer

如官方DRF文档中所述

在实例化序列化程序并传递many=True时，将创建一个ListSerializer实例。序列化程序类随后成为父child的ListSerializer。

例如，我们可以将MusicianSerializer重写为ListSerializer

class MusicianSerializer(serializers.ModelSerializer):
    albums = serializers.ListSerializer(child=AlbumSerializer(), source='album_set')

    class Meta:
        fields = '__all__'
        model = Musician

它会产生和以前一样的结果。但是，如果我们试图使用ListField而不是ListSerializer，它将引发一个错误

'RelatedManager' object is not iterable

当我检查源代码时，我发现ListSerializer和ListField都是从同一个类继承的(父类和父类是相同的)。

Answer 2

我遇到了同样的问题，我相信我找到了解决办法！

诀窍是您需要创建一个新的序列化程序，该序列化程序继承ListSerializer类并覆盖to_representation()方法以输出所需的格式。

如果您查看ListSerializer的DRF源代码，可以看到默认的to_representation()方法如下.

def to_representation(self, data):
        """
        List of object instances -> List of dicts of primitive datatypes.
        """
        # Dealing with nested relationships, data can be a Manager,
        # so, first get a queryset from the Manager if needed
        iterable = data.all() if isinstance(data, models.Manager) else data

        return [
            self.child.to_representation(item) for item in iterable
        ]

示例

模型

class Musician(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    instrument = models.CharField(max_length=100)

    def __str__(self):
        return f'{self.first_name} {self.last_name}'


class Album(models.Model):
    artist = models.ForeignKey(Musician, on_delete=models.CASCADE)
    name = models.CharField(max_length=100)
    release_date = models.DateField()
    num_stars = models.IntegerField()

    def __str__(self):
        return f'{self.name} : {self.artist}'

串行化

class AlbumSerializer(serializers.ModelSerializer):
    artist = serializers.StringRelatedField()

    class Meta:
        fields = '__all__'
        model = Album

class AlbumKeyValueSerializer(serializers.ListSerializer):
    def to_representation(self, data):
        reaction_count_set = {}
        for item in data.all():
            reaction_count_set[item.name] = item.artist

        return reaction_count_set

class MusicianSerializer(serializers.ModelSerializer):
    AlbumKeyValueSerializer(child=AlbumSerializer(), source='album_set')

    class Meta:
        fields = '__all__'
        model = Musician