How to serialize using django rest_framework for ManyToManyFields with a pass-through model

Question

I have a recipe model that contains the M2M field of an IngredientType object. This field, for example, componentent_list, uses the infamous "pass-through" model through the Ingredient object, which adds additional data to its IngredientType. these are my classes:

class Recipe(models.Model): user_profile = models.ForeignKey(UserProfile, null=True, blank = True) name = models.CharField(max_length=200) photo1 = models.ImageField( upload_to = 'images/recipies', help_text="This photo will show by default") ingredient_list = models.ManyToManyField(IngredientType,through='Ingredient') class Ingredient(models.Model): ingredient_type = models.ForeignKey(IngredientType) recipe = models.ForeignKey(Recipe) amount = models.IntegerField() units = models.CharField(max_length=4,choices=UNIT, default=None, null=True, blank = True) class IngredientType(models.Model): name = models.CharField(max_length=200) plural_name = models.CharField(max_length=200) photo = models.ImageField( upload_to = 'images/ingredients') is_main = models.BooleanField() 

I tried serializing them using rest_framework:

 class IngredientTypeSerializer(serializers.HyperlinkedModelSerializer): class Meta: model = IngredientType fields=('name', 'plural_name', 'photo', 'is_main') class IngredientSerializer(serializers.HyperlinkedModelSerializer): ingredient_type = IngredientTypeSerializer(source = 'ingredient_type') amount = serializers.Field(source='ingredient_type.amount') units = serializers.Field(source='ingredient_type.units') recipe = serializers.Field(source='Recipe.name') class Meta: model = Ingredient fields=('amount', 'units') class RecipeSerializer(serializers.ModelSerializer): ingredient_list = IngredientSerializer(source='ingredient_list', many=True, read_only = True) class Meta: model = Recipe fields = ('user_profile', 'name','photo1','ingredient_list') 

but when I try to run this, I get an AttributeError: The object "IngredientType" does not have the attribute "componentent_type"

clear when i change the line:

 ingredient_list = IngredientSerializer(source='ingredient_list', many=True, read_only = True) 

in

 ingredient_list = IngredientTypeSerializer(source='ingredient_list', many=True, read_only = True) 

that is, change the Serializer, it works, but without collecting the Ingredient data. I used this link: Include the intermediary (through the model) in the answers in the Django Rest Framework as a link, but obviously it did not solve my problems.
Any help would be greatly appreciated. Ty, nitzan

Answer 1

In your Recipe model for the ingredient_list field, you have ManyToManyField pointing to IngredientType .

On your RecipeSerializer the ingredient_list field does not use the IngredientTypeSerializer , but rather the IngredientSerializer .

This is mistake. (And he explains the error message - the actual model in source does not have the attribute that the serializer is looking for.)

Other than that, your naming scheme is massively confusing. The “recipe” is fine, but what you call “IngredientType” should just be “Ingredient,” and then you should find a great name for the pass-through table. (Maybe "RecipeIngredientDetails")

I hope this helps.