Override 'create' function in Django serializer - django

Question

I wonder how to handle POST request to properly save the incoming data, having such models:
class Recipe(models.Model):
author = models.ForeignKey('auth.user', related_name='recipes', on_delete=models.CASCADE)
image = models.TextField(default='None')
name = models.CharField(max_length=100)
description = models.TextField(default='No description')
votes = models.IntegerField(default=0)
def __str__(self):
return self.name
class Ingredient(models.Model):
image = models.TextField(default='None')
name = models.CharField(max_length=100)
description = models.TextField(default='No description')
price = models.DecimalField(max_digits=8, decimal_places=3)
unit_price = models.DecimalField(max_digits=8, decimal_places=3)
unit_quantity = models.CharField(max_length=20)
def __str__(self):
return self.name
I wanted to avoid duplicating Ingredient objects, so to provide quantity of specific Ingredient in Recipe I've created a RecipesIngredient model that binds Ingredient with Recipe, but also contains a quantity of this Ingredient:
class RecipesIngredient(models.Model):
recipe = models.ForeignKey(Recipe, related_name='ingredients', on_delete=models.CASCADE)
ingredient = models.ForeignKey(Ingredient, on_delete=models.CASCADE)
quantity = models.CharField(max_length=100)
def __str__(self):
return self.quantity
I've also prepared some serializers for these models:
class IngredientSerializer(HyperlinkedModelSerializer):
class Meta:
model = Ingredient
fields = (
'url',
'image',
'name',
'description',
'price',
'unit_price',
'unit_quantity'
)
class RecipesIngredientSerializer(HyperlinkedModelSerializer):
ingredient_name = ReadOnlyField(source='ingredient.name')
ingredient_price = ReadOnlyField(source='ingredient.price')
ingredient_unit_price = ReadOnlyField(source='ingredient.unit_price')
ingredient_unit_quantity = ReadOnlyField(source='ingredient.unit_quantity')
class Meta:
model = RecipesIngredient
fields = (
'url',
'ingredient_name',
'quantity',
'ingredient_price',
'ingredient_unit_price',
'ingredient_unit_quantity'
)
class RecipeListSerializer(HyperlinkedModelSerializer):
author = ReadOnlyField(source='author.username')
author_url = ReadOnlyField(source='author.url')
class Meta:
model = Recipe
fields = (
'url',
'author',
'author_url',
'image',
'name',
'description',
'votes'
)
class RecipeDetailSerializer(HyperlinkedModelSerializer):
author = ReadOnlyField(source='author.username')
author_url = ReadOnlyField(source='author.url')
ingredients = RecipesIngredientSerializer(many=True)
class Meta:
model = Recipe
fields = (
'url',
'author',
'author_url',
'image',
'name',
'description',
'ingredients',
'votes'
)
But in this case, I have to first create a Recipe instance and save it to DB, then do the same with Ingredient to be able to "bind" them in RecipesIngredient. Is this possible to handle this case with only one POST request to view below?
#
# path('recipes/', views.RecipeList.as_view(), name='recipe-list')
#
class RecipeList(generics.ListCreateAPIView):
queryset = Recipe.objects.all()
serializer_class = RecipeListSerializer
def perform_create(self, serializer):
serializer.save(author=self.request.user)
#EDIT
I forgot 'bout this thread, but the problem is solved now. I've prepared another serializer for CREATE purposes only, and overridden the 'create' function of this serializer.:
class RecipeCreateSerializer(HyperlinkedModelSerializer):
#author = ReadOnlyField(source='author.username')
#author_url = ReadOnlyField(source='author.url')
recipes_ingredients = RecipesIngredientCreateSerializer(many=True)
def create(self, validated_data):
recipes_ingredients = validated_data.pop('recipes_ingredients')
recipe_instance = super().create(validated_data)
for recipe_ingredient in recipes_ingredients:
ingredient_data = recipe_ingredient.pop('ingredient')
ingredient_instance = Ingredient(
image=ingredient_data['image'],
name=ingredient_data['name'],
description=ingredient_data['description'],
price=ingredient_data['price'],
unit_price=ingredient_data['unit_price'],
unit_quantity=ingredient_data['unit_quantity'],
)
ingredient_instance.save()
recipes_ingredient_instance = RecipesIngredient(
recipe=recipe_instance,
ingredient=ingredient_instance,
quantity=recipe_ingredient['quantity']
)
recipes_ingredient_instance.save()
return recipe_instance
class Meta:
model = Recipe
fields = (
'url',
'image',
'name',
'description',
'votes',
'recipes_ingredients',
)
Also the JSON file looks a bit different now, but everything works just fine:
{
"image": "image-url",
"name": "recipes-name",
"description": "recipes-description",
"votes": 0,
"recipes_ingredients": [
{
"quantity": "ingredients-quantity",
"ingredient": {
"image": "image-url",
"name": ingredient-name",
"description": "ingredient-description",
"price": 3.6,
"unit_price": 0.36,
"unit_quantity": "100ML"
}
},
{
"quantity": "ingredients-quantity",
"ingredient": {
"image": "image-url",
"name": ingredient-name",
"description": "ingredient-description",
"price": 0.3,
"unit_price": 0.3,
"unit_quantity": "EACH"
}
},
{
"quantity": "ingredients-quantity",
"ingredient": {
"image": "image-url",
"name": ingredient-name",
"description": "ingredient-description",
"price": 2.0,
"unit_price": 0.8,
"unit_quantity": "KG"
}
}
]
}