DRF ForeignKey值未部分显示

Question

I am newbie in python django, just couple weeks. And this is my first question post.

I found problems using DRF ForeignKey. The foreign key value (name) do not showing up. I have 3 tables which are related each other (Brand, Country, BrandCountry). After followed some tutorials, in BrandCountry Entity, I succeed print out the name of brand (instead of ID), but it is not working with the same code structure for country relation. country name not showing

I wonder what is the problem causing this. There is no error or warning message. I tried to debug, the query run correctly (it selects brand.name and country.name correctly). correct query from debug

I wonder is it because of : - I use 'code' for relation key instead of 'ID'?

• the name of the Country contains Kanji(special character)?

• or is there something i miss?

Models.py

class BrandCountry(models.Model):
    class Meta:
        db_table = 'brand_countries'

    brand = models.ForeignKey(to='brand.Brand', on_delete=models.CASCADE, related_name='ref_brand_country_brand')
    country_code = models.ForeignKey(to='country.Country',
                                    on_delete=models.CASCADE,
                                    related_name='ref_brand_country_country',
                                    max_length=45,
                                    db_column='country_code',
                                    to_field='code')

Serializers.py

class BrandCountrySerializer(serializers.ModelSerializer):
    brand_name = serializers.StringRelatedField(source='brand.name')
    country_name = serializers.StringRelatedField(source='country.name')

    class Meta:
        model = BrandCountry
        fields = ('id', 'brand_id', 'brand_name', 'country_code', 'country_name')

    @staticmethod
    def setup_eager_loading(queryset):
        queryset = queryset.select_related('brand','country_code')
        return queryset

Views.py

class BrandCountryListView(generics.ListAPIView):
    serializer_class = BrandCountrySerializer
    brand_id = "brand_id"

    def get_queryset(self):
        serializer_class = BrandCountrySerializer.setup_eager_loading(BrandCountry.objects)
        queryset = serializer_class.all()
        brand_id = self.kwargs.get(self.brand_id)
        queryset = queryset.filter(brand_id=brand_id)

        return queryset

I tried to debug and find the solution here and there almost spend more than 1 days, but no result. If there someone can help me, I really appreciate it. Sorry if something is missing or unclear.

Answer 1

You are using wrong refference for country_name in serializer. So change source='country.name' to source='country_code.name'

class BrandCountrySerializer(serializers.ModelSerializer):
    brand_name = serializers.StringRelatedField(source='brand.name')
    country_name = serializers.StringRelatedField() # Change is here <<<<

    class Meta:
        model = BrandCountry
        fields = ('id', 'brand_id', 'brand_name', 'country_code', 'country_name')

    @staticmethod
    def setup_eager_loading(queryset):
        queryset = queryset.select_related('brand','country_code')
        return queryset

UPDATE
You can try depth attribute, as:

class BrandCountrySerializer(serializers.ModelSerializer):
    class Meta:
        model = BrandCountry
        fields = '__all__'
        

    @staticmethod
    def setup_eager_loading(queryset):
        queryset = queryset.select_related('brand', 'country_code')
        return queryset