# How to use a single serializer to save multiple models

**URL:** <https://forum.djangoproject.com/t/how-to-use-a-single-serializer-to-save-multiple-models/33370>\
**Category:** Mystery Errors\
**Created:** [July 29, 2024, 1:48am UTC](https://forum.djangoproject.com/t/how-to-use-a-single-serializer-to-save-multiple-models/33370 "2024-07-29T01:48:16Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![bhati00](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/bhati00/32/22373_2.png) [@bhati00](https://forum.djangoproject.com/u/bhati00)\
**Post date:** [July 29, 2024, 1:48am UTC](https://forum.djangoproject.com/t/how-to-use-a-single-serializer-to-save-multiple-models/33370/1 "2024-07-29T01:48:16Z")

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> Problem : I’m unable to save the both models in database from a single serialzer.

> Description : I’m using djoser auth library for registration and authentication. for that i’m using custom django auth user and mapped it with userprofile model.  
> Since i’m using userprofile along with the django user, i have to use custom register serializer.

```auto
# My Models
class CustomUser(AbstractUser):
    username = None
    email = models.EmailField(_("email address"), unique=True)
    
    USERNAME_FIELD = "email"
    REQUIRED_FIELDS = []
    
    objects = CustomUserManager()
    
class UserProfile(models.Model):
    user = models.OneToOneField(CustomUser, on_delete=models.CASCADE, related_name="userProfile")
    user_guid = models.UUIDField(
        default=uuid.uuid4,
        unique=True,
        editable=False
    )
    user_type = models.IntegerField(choices=UserType.choices(), default=UserType.BUYER)
    wallet_balance = models.FloatField()
    created_at = models.DateTimeField(auto_now=True)
    updated_at = models.DateTimeField(auto_now_add=True)
    
    class Meta:
        ordering = ['created_at'] # Corrected the ordering syntax

```

```auto
#My Serializer
CustomUser = get_user_model()

class UserProfileSerializer(serializers.ModelSerializer):
    class Meta:
        model = UserProfile
        fields = ['user_guid', 'user_type', 'wallet_balance', 'created_at', 'updated_at']
        read_only_fields = ['user_guid', 'created_at', 'updated_at']

class CustomUserCreateSerializer(DjoserUserCreateSerializer):
    userProfile = UserProfileSerializer()

    class Meta:
        model = CustomUser
        fields = ['id', 'email', 'password', 'userProfile']
        extra_kwargs = {'password': {'write_only': True}}

    def create(self, validated_data):
        user_profile_data = validated_data.pop('userProfile')
        user = CustomUser.objects.create_user(**validated_data)
        
        UserProfile.objects.create(user=user, **user_profile_data)
        return user

```

```auto
#settings.py
# django auth model
AUTH_USER_MODEL = 'users.CustomUser'

# djoser settings
DJOSER = {
    'SERIALIZERS': {
        'user_create': 'users.v1.serializers.CustomUserCreateSerializer',
        'user': 'users.v1.serializers.CustomUserCreateSerializer',
        'current_user': 'users.v1.serializers.CustomUserCreateSerializer',
    }
}

```

> Error : raise ValueError(  
> ValueError: Cannot assign “{‘user\_type’: 1, ‘wallet\_balance’: 0.0}”: “CustomUser.userProfile” must be a “UserProfile” instance.

---

<div class="post-metadata">

**Author:** ![theorangeone](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/theorangeone/32/21264_2.png) [@theorangeone](https://forum.djangoproject.com/u/theorangeone)\
**Post date:** [July 29, 2024, 1:29pm UTC](https://forum.djangoproject.com/t/how-to-use-a-single-serializer-to-save-multiple-models/33370/2 "2024-07-29T13:29:25Z")

</div>

The code you have in `create` looks to follow what DRF recommends: [Serializers - Django REST framework](https://www.django-rest-framework.org/api-guide/serializers/#writable-nested-representations)

With the error you’re getting, you should be able to use the full stacktrace to work out where it’s coming from. Your code is trying to _assign_ the user profile, which your custom code isn’t doing, so I’d expect the error is coming from elsewhere, which the stacktrace should help you narrow down.

---

<div class="post-metadata">

**Author:** ![bhati00](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/bhati00/32/22373_2.png) [@bhati00](https://forum.djangoproject.com/u/bhati00)\
**Post date:** [July 30, 2024, 12:45am UTC](https://forum.djangoproject.com/t/how-to-use-a-single-serializer-to-save-multiple-models/33370/3 "2024-07-30T00:45:19Z")

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@theorangeone , thank you for your reply. I’m trying to figure it out.

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<div class="post-metadata">

**Author:** ![bhati00](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/bhati00/32/22373_2.png) [@bhati00](https://forum.djangoproject.com/u/bhati00)\
**Post date:** [July 30, 2024, 5:09am UTC](https://forum.djangoproject.com/t/how-to-use-a-single-serializer-to-save-multiple-models/33370/4 "2024-07-30T05:09:10Z")

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if somebody faced this same problem, here is [solution](https://stackoverflow.com/questions/78805702/how-to-use-a-single-serializer-to-save-multiple-models/78809390#78809390)