目标：想要把image的‘image_select’字段显示出来

方法一：要使用HyperlinkedIdentityField,然而由于我把lookup_field已经占用了，就不能在修改为lookup_field =‘image_select”所以这种方法不幸’还要修改我的其它代码

class AlbumSerializer(serializers.HyperlinkedModelSerializer):
    track_listing = serializers.HyperlinkedIdentityField(view_name='track-list')

    class Meta:
        model = Album
        fields = ('album_name', 'artist', 'track_listing')

方法二：Nested relationships中讲解到

class TrackSerializer(serializers.ModelSerializer):
    class Meta:
        model = Track
        fields = ('order', 'title', 'duration')

class AlbumSerializer(serializers.ModelSerializer):
    tracks = TrackSerializer(many=True, read_only=True)

    class Meta:
        model = Album
        fields = ('album_name', 'artist', 'tracks')

所以如下

class ProductDetailSerializer(serializers.ModelSerializer):
    image=ImageItemsSerializer(read_only=True)
    class Meta:
         model = ProductDetail
         fields = "__all__"

方法三：depth可以直接打开外键关系关联的对象

class ProductDetailSerializer(serializers.ModelSerializer):
    class Meta:
         model = ProductDetail
         fields = "__all__"
         depth = 1