Django Rest Framework-相關的序列化器

Question

給定以下模型，其中兩個模型與第一個模型具有ManyToMany關系，如何為所有三個模型構造序列化器？

這就是在Python中進行排序的重要性正成為一個問題的地方。

class Trail(models.Model):
    '''
    Main model for this application.  Contains all information for a particular trail
    '''
    trail_name = models.CharField(max_length=150)
    active = models.BooleanField(default=True)
    date_uploaded = models.DateTimeField(default=now())
    owner = models.ForeignKey(Account, default=1)


    class Meta:
        ordering = ('trail_name', )

class Activity(models.Model):
    '''
    A many to many join table to map an activity name to a trail.  A trail can have many
    activities
    '''
    name = models.CharField(max_length=40, unique=True)
    trails = models.ManyToManyField(Trail)

    class Meta:
        ordering = ('name', )


class Surface(models.Model):
    '''
    A many to many join table to map a surface type to many trails.  A trail can have many
    surface types.
    '''
    type = models.CharField(max_length=50, db_column='surface_type', unique=True)
    trails = models.ManyToManyField(Trail)

    class Meta:
        ordering = ('type', )

我在serializers.py中有以下序列serializers.py ：

class TrailSerializer(serializers.ModelSerializer):
    owner = AccountSerializer()
    activities = ActivitySerializer()

    class Meta:
        model = Trail
        fields = ('trail_name', 'active', 'date_uploaded', 'owner', 'activities', )


class ActivitySerializer(serializers.ModelSerializer):
    trails = TrailSerializer()

    class Meta:
        model = Activity
        fields = ('trails', 'name', )


class SurfaceSerializer(serializers.ModelSerializer):
    trails = TrailSerializer()

    class Meta:
        model = Surface
        fields = ('trails', 'type', )

我的問題是，沒有創建另一個包含ActivitySerializer and SurfaceSerializer文件，我如何確保TrailSerializer可以按預期工作，以便在序列化期間包括Activity和Surface引用？

Answer 1

使用棉花糖 （序列化庫部分受DRF序列化程序啟發）。 通過允許將嵌套模式作為字符串引用來解決此問題。 參見棉花糖：雙向嵌套

class AuthorSchema(Schema):
    # Make sure to use the 'only' or 'exclude' params to avoid infinite recursion
    books = fields.Nested('BookSchema', many=True, exclude=('author', ))
    class Meta:
        fields = ('id', 'name', 'books')

class BookSchema(Schema):
    author = fields.Nested(AuthorSchema, only=('id', 'name'))
    class Meta:
        fields = ('id', 'title', 'author')

您可以直接使用，也可以通過Tom Christie的 django-rest-marshmellow使用，它允許使用棉花糖，同時保持與REST框架的Serializer類相同的API。

我不知道僅使用DRF序列化器即可達到相同結果的方法。

另請參閱： 為什么選擇棉花糖？