[Fixed]-Django REST framework: save related models in ModelViewSet

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21👍

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I was dealing with similiar issue this week and I found out, that django rest framework 3 actually supports nested writable serialisation (http://www.django-rest-framework.org/topics/3.0-announcement/#serializers in subchapter Writable nested serialization.)

Im not sure if nested serialisers are writable be default, so I declared them:

ingredients = RecipeIngredientSerializer(many=True, read_only=False)
steps = RecipeStepSerializer(many=True, read_only=False)

and you should rewrite your create methon inside RecipeSerializer:

class RecipeSerializer(serializers.ModelSerializer):
    ingredients = RecipeIngredientSerializer(many=True, read_only=False)
    steps = RecipeStepSerializer(many=True, read_only=False)

    class Meta:
        model = Recipe
        fields = (
            'name', 'dish_type', 'cooking_time', 'steps', 'ingredients'
        )

    def create(self, validated_data):
        ingredients_data = validated_data.pop('ingredients')
        steps_data = validated_data.pop('steps')
        recipe = Recipe.objects.create(**validated_data)
        for ingredient in ingredients_data:
            #any ingredient logic here
            Ingredient.objects.create(recipe=recipe, **ingredient)
        for step in steps_data:
            #any step logic here
            Step.objects.create(recipe=recipe, **step)
        return recipe

if this structure Step.objects.create(recipe=recipe, **step) wont work, maybe you have to select data representeng each field separatly from steps_data / ingredients_data.

This is link to my earlier (realted) question/answer on stack: How to create multiple objects (related) with one request in DRF?

👤Matúš Bartko

1👍

I think that I get the answer.

class RecetaSerializer(serializers.ModelSerializer):

    ingredientes = IngredientesSerializer(many=True, partial=True)
    autor = serializers.PrimaryKeyRelatedField(queryset=User.objects.all())
    depth = 2

    class Meta:
        model = Receta
        fields = ('url','pk','nombre','foto','sabias_que','ingredientes','pasos','fecha_publicacion','autor')   

    def to_internal_value(self,data):

        data["fecha_publicacion"] = timezone.now()
        ingredientes_data = data["ingredientes"]
      
        for ingrediente in ingredientes_data:
                       
            alimento_data = ingrediente["alimento"]
                     
            if Alimento.objects.filter(codigo = alimento_data['codigo']).exists():

                alimento = Alimento.objects.get(codigo= alimento_data['codigo'])              
                ingrediente["alimento"] = alimento

            else:
                alimento = Alimento(codigo = alimento_data['codigo'], nombre = alimento_data['nombre'])
                alimento.save()                
                ingrediente["alimento"] = alimento
        data["ingredientes"] = ingredientes_data
        return data

    def create(self, validated_data):
              
        ingredientes_data = validated_data.pop('ingredientes')
        
        receta_data = validated_data
        usuario = User.objects.get(id = validated_data["autor"])
        receta_data['autor'] = usuario
       
        receta = Receta.objects.create(**validated_data)
        
        
        for ingrediente in ingredientes_data:
            
            alimento_data = ingrediente["alimento"]
            ingrediente = Ingredientes(receta= receta, cantidad = ingrediente['cantidad'], unidad = ingrediente['unidad'], alimento = alimento_data)
            ingrediente.save()
        
        receta.save()
            
            
        return receta

It’s important to override to_internal_value(). I had problems with the function is_valid(). So every change make in the function to_internal_value() is before the function is_valid()

👤Sonia

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