Missing data from validated_data in django rest framwork

Question

I'm building a web app and trying to send Post data as FormData to a Django Rest Framework Serializer. In the request.data I see that all the Post data is there, however after validating and saving the serializer it seems like some of the data did not get passed into validated_data.

Views.py

@api_view(["GET","POST"])
def api_list(request):
    if request.method=="GET":
        data = Recipe.objects.all()

        serializer = RecipeSerializer(data, many=True)

        return Response(serializer.data)

    elif request.method=="POST":
        print("POST recieved")
        print (request.data) <----See below
        serializer = RecipeSerializer(data=request.data)
        print("Validating..")
        if serializer.is_valid():
            print("validated!")
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        print (serializer.errors)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

request.data

<QueryDict: 
{'description': ['"gfdgdfg"'], 
 'name': ['"fdgdfgdf"'], 
 'ingredients': [
     '{"name":"dfgdfg","amount":"gdfgd"}', 
     '{"name":"fdgdfg","amount":"dfgdf"}', 
     '{"name":"dfgdfgdf","amount":"gdfgdf"}'
 ], 
 'directions': [
     '{"content":"gdfgfd"}', 
     '{"content":"gdfgdfg"}', 
     '{"content":"dfgdfdfg"}'
  ], 
'image': [
      <InMemoryUploadedFile: luisana-zerpa-MJPr6nOdppw-unsplash.jpg (image/jpeg)>
 ]
}>

serializer.py

class IngredientSerializer(serializers.ModelSerializer):

    class Meta:
        model = Ingredient
        fields = ('name', 'amount')

class DirectionSerializer(serializers.ModelSerializer):

    class Meta:
        model = Direction
        fields = ('content',)


class RecipeSerializer(serializers.ModelSerializer):
    owner = serializers.StringRelatedField()
    ingredients = IngredientSerializer(many=True, read_only=False)
    directions = DirectionSerializer(many=True, read_only=False)
    class Meta:
        model = Recipe
        fields = (
            'id',
            'name',
            'owner',
            'image',
            'description',
            'created_at',
            'ingredients',
            'directions',
        )


    def create(self, validated_data):
        print (validated_data) <----See Below

        has_ingredients = validated_data.get("ingredients")
        has_directions = validated_data.get("directions")

        if has_ingredients:
            ingredient_data = validated_data.pop('ingredients')
        if has_directions:
            direction_data = validated_data.pop('directions')

        recipe_name = validated_data.get('name')
        recipe_name = recipe_name.replace('"','')

        recipe_description = validated_data.get('description')
        recipe_description = recipe_description.replace('"','')


        recipe = Recipe.objects.create(name=recipe_name, description=recipe_description, image=validated_data.get('image'))
    
        if has_ingredients:
            for ingredient in ingredient_data:
                Ingredient.objects.create(recipe=recipe, name=ingredient.get("name"), amount=ingredient.get("amount"))
        if has_directions:
            for direction in direction_data:
                Direction.objects.create(recipe=recipe, content=direction.get("content"))
        return recipe

validated_data NOTE: I can only get this if I add "required=False" for ingredient and directions else it just return a 404err

{
 'name': '"fdgdfgdf"', 
 'image': <InMemoryUploadedFile: luisana-zerpa-MJPr6nOdppw-unsplash.jpg (image/jpeg)>, 
 'description': '"gfdgdfg"'
 }

I tried looking into overiding the .is_valid() method on the serializers but I couldn't find anything on the official documentation. If I used the Postman app to Post data everything works however whenever I sent data from my frontend this happens. I wonder if I has anything to do with how i'm sending the data but I don't want to include too much unnecessary.

Thanks in advance for any help :)

Did you use name attributes for the fields you are not getting the data for? — K14
– K14, Commented Oct 14, 2022 at 15:20
@Nealium It gives a 400 error because it can't find ingredients or directions in validated_data. {'ingredients': [ErrorDetail(string='This field is required.', code='required')], 'directions': [ErrorDetail(string='This field is required.', code='required')]} — Thanh Nguyen
– Thanh Nguyen, Commented Oct 18, 2022 at 2:10

Marcos Oliveira · Accepted Answer · 2022-10-15 04:25:41Z

0

I believe you are forgetting to send the ingredients and directions to the new recipe instance.

This is why your POST endpoint only works when they are not required

You can create the relationship with Recipe after you create the Ingredient instance

ingredient = Ingredient.objects.create(**inputs)
recipe.ingredient = ingredient
recipe.save()

Same goes for Direction:

direction = Direction.objects.create(**inputs)
recipe.direction = direction
recipe.save()

They were already validated in IngredientSerializer and DirectionSerializer, so you can safely create the relationship with Recipe

Quick tip: If you have a flag called has_ingredients, you probably mean that you can have recipies without ingredients, in this case, the field should be required=False

If you need the ingredients and directions filelds to be required, you will need to create the recipe with all the inputs, for example:

recipe = Recipe.objects.create(
    name=recipe_name, 
    description=recipe_description, 
    image=validated_data.get('image'),
    ingredient=ingredient,
    direction=direction
)

Another way around: you can create a Recipe instance first with some fields, then add the ingredient and direction and finally call .save() to register the new database entry.

edited Oct 15, 2022 at 4:25

answered Oct 14, 2022 at 18:10

Marcos Oliveira

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2 Comments

Thanh Nguyen Over a year ago

The issue i'm having is that I'm supposed to create the Ingredient and Directions database entry from the Serializer.py file. So w/o the ingredients data and directions data inside of validated_data prop I can't make the ingredients or directions model instance.

Marcos Oliveira Over a year ago

Try removing the read_only input

Thanh Nguyen · Accepted Answer · 2022-10-18 05:42:44Z

I've Figured out the Answer!

The problem all along was in how I was Posting the data.

Originally I was sending the post data for "ingredients" and "directions like this"...

ingredients.forEach((ingredient) => {
    formData.append('ingredients',{
        'name':ingredients.name,
        'amount':ingredient.amount
    });
});

I had a forEach loop for "directions" as well and it pretty much followed the same pattern.

The Correct way to post a List of Objects using multipart/form-data should be like this

ingredients.forEach((ingredient, index) => {
        formData.append(`ingredients[${index}]name`, JSON.stringify(ingredient.name));
        formData.append(`ingredients[${index}]amount`, JSON.stringify(ingredient.amount))
    });

The difference is that when posting a list we have to detail the the exact path to for each item in the list.

e.g formData.append(ingredients[${index}]name, JSON.stringify(ingredient.name));

That's about all I know, if anyone has more information on what we need to do that please add on, since there is not much information on why this is the case.

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