Only id is returing in nested serializer django rest framework

Question

I have two models user and notes, my aim is to get a JSON response like this.

{
"status": 200,
"data": [
    {
        "id": 1,
        "note": "dd",
        "created_on": "2022-10-03T06:58:33.337137Z",
        "is_active": true,
        "created_by":[{
           "username":"loream",
           "email":"username@gmail.com",
           ...........

         }
       ]
    },
    
]}

Modals are :

class Notes(models.Model):
   note= models.TextField()
   created_on=models.DateTimeField(auto_now_add=True)
   is_active=models.BooleanField(default=True)
user=models.ForeignKey(UserModal,on_delete=models.CASCADE,null=True,related_name="created_byy",blank=True)



class UserModal(AbstractUser):
  username = models.CharField(max_length=30,unique=True)
  password = models.CharField(max_length=30)
  email = models.EmailField(blank=True)

serializers I wrote is

class UserSerializer(serializers.ModelSerializer):

   class Meta:
     model = UserModal
     fields = '__all__'

class NotesSerializer(serializers.ModelSerializer):
   created_byy = UserSerializer(many=True,read_only=True)
   class Meta:
     model=Notes
    fields='__all__'

But I couldn't get a JSON response as expected I'm getting responses like this

{
"status": 200,
"data": [
    {
        "id": 1,
        "note": "dd",
        "created_on": "2022-10-03T06:58:33.337137Z",
        "is_active": true,
        "user": 1
    },
    
]

}

how can I achieve the expected result?

Try to update `NotesSerializer` with `fields = ("id", "note", "created_on", "is_active", "created_byy")` in `Meta`. — wiaterb, Oct 03 '22 at 10:49
I have tried that, but still, I'm getting the same response. Is it any problem in defining the modal class for nested serializers? — Akhil, Oct 03 '22 at 10:54

ThomasGth · Answer 1 · 2022-10-14T08:05:01.467

To fix this, change your serializer as follows:

class NotesSerializer(serializers.ModelSerializer):
    user = UserSerializer(read_only=True)  # user instead of created_byy, and no many=True
    class Meta:
        model = Notes
        fields = '__all__'

Some explanations:
The problem you have is created_byy does not exist in your Notes model, it's the name of the attribute to get the queryset of notes from a user instance.
Basically, using user.created_byy.all() would get you all notes related to this user.
Mode details about related_name in this post.

user is the attribute you declared in your model, that's why you still retrieve it when using fields='__all__', and that's definitely the one you want.

If you really want your user to be named "created_by", just use a SerializerMethodField (docs here):

class NotesSerializer(serializers.ModelSerializer):
    created_by = serializers.SerializerMethodField()

    def get_created_by(self, instance):
        return UserSerializer(instance.user)

    # Better way to do this using "source" (shoutout to @mon io).
    # No need to define get_created_by() this way.
    created_by = UserSerializer(source='user', read_only=True)

    class Meta:
        model = Notes
        fields = ['id', 'note', 'created_on', 'created_by', 'is_active']

Also, you cannot have an array of users in both cases, because of how you declared your one-to-many (one user can have several notes, the opposite is false).

On a final note, you really should rename the created_byy to notes so it's less confusing.

I have given "created_byy" as the related name in the notes model — Akhil, Oct 03 '22 at 12:59
@Akhil The related_name attribute specifies the name of the reverse relation from the User model back to your model (more details [here](https://stackoverflow.com/a/2642645/6106166)). You can check that by yourself, try to call `Notes.objects.first().user`, then `Notes.objects.first().created_byy`. If you have at least one note, the first one will work, the second one will raise an exception. That's why you **must** use instance.user and not instance.created_byy. — ThomasGth, Oct 03 '22 at 13:51

score 0 · Answer 2 · answered Oct 03 '22 at 22:36

0

@ThomasGth give you nice explanation.

Here is quick solution from me

class NotesSerializer(serializers.ModelSerializer):
    created_by = UserSerializer(source='user', read_only=True)

    class Meta:
        model = Notes
        fields = ['id', 'note', 'created_on', 'created_by', 'is_active']

answered Oct 03 '22 at 22:36

mon io

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1

Momentarily forgot about `source` for some reason, but it's definitely more elegant this way. – ThomasGth Oct 04 '22 at 15:10

Only id is returing in nested serializer django rest framework

2 Answers2