accessing 2 foreign key fields at the same time in django serializers

Question

I have the following models in my django rest framework project. in this project there are products and they have producers and importers.

# models.py
class Product(models.Model):
    name = models.CharField(max_length=255)
    producer = models.ManyToManyField(Company, related_name='producer')
    importer = models.ManyToManyField(Company, related_name='importer')

class Company(models.Model):
    name = models.CharField(max_length=255)

I need to make an API which retrieves an instance of the "Company" model and gives me a list of the products they have produced and another list for the products that they have imported

Now I know to do this with only one manytomany field, I can do the following:

class CompanyRetrieveSerializer(serializers.ModelSerializer):
    class ProductSerializer(serializers.ModelSerializer):
        class Meta:
            model = Product
            fields = ('name',)
    
    product_set = ProductSerializer(read_only=True, many=True,)
    class Meta:
        model = Company
        fields = '__all__'

but since there are two fields in the product model that reference the company model, this doesn't work. Is there any way to fix this issue?

Answer 1

Tehe reason this does not work is because you specified related_name='producer': related_name is the name of the relation in reverse, so it makes not much sense to name this producer. You can rename the relations to:

class Product(models.Model):
    name = models.CharField(max_length=255)
    producer = models.ManyToManyField(Company, related_name='produced_products')
    importer = models.ManyToManyField(Company, related_name='imported_products')

then you can serialize the two relations with:

class CompanyRetrieveSerializer(serializers.ModelSerializer):
    class ProductSerializer(serializers.ModelSerializer):
        class Meta:
            model = Product
            fields = ('name',)
    
    produced_products = ProductSerializer(read_only=True, many=True)
    imported_products = ProductSerializer(read_only=True, many=True)
    
    class Meta:
        model = Company
        fields = '__all__'