Nested Serializer creates new object-CodePudding

I have a serializer called EntrySerializer and it should return the staff details but if I want to create a new entry it wants to create a new staff object and throws an error. Is there anything like a read only field for my serializer? It should create a new entry but assign an already created staff object.

class EntrySerializer(serializers.ModelSerializer):

    staff = serializers.SerializerMethodField('get_staff')

    def get_staff(self, obj):
        return MyUserSerializer(obj.staff).data

    class Meta:
        model = Entry
        depth = 1
        fields = ('time_spend', 'staff',)

Error:

django.db.utils.IntegrityError: ERROR: NULL-value in Column »staff_id« relation »tagesbericht_tagesbericht_Entry« Not-Null-Constraint DETAIL: (54, 00:00:08.5, null, 61).

POST:

"tagesbericht_entry_set": [ { "staff": 2, "time_spend": "00:12:08" } ]

CodePudding user response：

I think you need to add the staff_id field for writing.

class EntrySerializer(serializers.ModelSerializer):
    staff = MyUserSerializer(read_only = True)
    staff_id = Serializers.IntegerField(write_only = True)

    class Meta:
        model = Entry
        depth = 1
        fields = ('time_spend', 'staff', 'staff_id')

And the POST payload should be

{
    "staff_id": 2,
    "time_spend": "00:12:08"
}