# Serializer saves to db but returns 500 bad request

**URL:** <https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385>\
**Category:** Forms & APIs\
**Created:** [November 16, 2023, 1:22pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385 "2023-11-16T13:22:34Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:22pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/1 "2023-11-16T13:22:34Z")

</div>

I am trying to create a serializer to get user input and insert it in a patient record, to do this i have several models connected using foreignkey but when i send the data using postman the data gets saved in the dp but the api responds with a 500 bad request !!!

console

```auto
Validated data before pop: {'ticket': 2, 'pressure': '125/75', 'diabetes': 123}
Ticket value after pop: 2
User's convoy: Test 2
Appointment found:
Patient Test
Validated data before creating Detection: {'pressure': '125/75', 'diabetes': 123, 'ticket': <Appointment: Patient Test>}
Detection created: Patient Test
2 125/75 123
Internal Server Error: /early/api/detection/
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/django/core/handlers/exception.py", line 55, in inner       
    response = get_response(request)
  File "/usr/local/lib/python3.9/site-packages/django/core/handlers/base.py", line 197, in _get_response   
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/views/decorators/csrf.py", line 56, in wrapper_view  
    return view_func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/views/generic/base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 469, in handle_exception     
    self.raise_uncaught_exception(exc)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "/app/earlyDetection/views.py", line 16, in post
    return Response(serializer.data, status=status.HTTP_201_CREATED)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/serializers.py", line 555, in data
    ret = super().data
  File "/usr/local/lib/python3.9/site-packages/rest_framework/serializers.py", line 253, in data
    self._data = self.to_representation(self.instance)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/serializers.py", line 522, in to_representation
    ret[field.field_name] = field.to_representation(attribute)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/fields.py", line 915, in to_representation   
    return int(value)
TypeError: int() argument must be a string, a bytes-like object or a number, not 'Appointment'
[16/Nov/2023 15:18:26] "POST /early/api/detection/ HTTP/1.1" 500 102016

```

models.py

```auto
class Detection(models.Model):
    # Unique identifier for each appointment
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False, max_length=36)
    # Patients's number
    ticket = models.ForeignKey(Appointment, on_delete=models.CASCADE)
    # Blood pressure
    pressure = models.CharField(max_length=10)
    # Diabeties reading
    diabetes = models.IntegerField()
    # Accumulated diabeties reading
    acc_Diabetes = models.IntegerField(null= True, blank= True)
    # Extra Fields
    field = models.ForeignKey(Field, on_delete=models.CASCADE, null= True, blank= True)
    # Date of detection
    createdAt = models.DateTimeField(auto_now_add=True)

    def __str__ (self):
        return f'{self.ticket.patient.first_name} {self.ticket.patient.last_name}'

class Appointment(models.Model):
    # Unique identifier for each appointment
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False, max_length=36)
    # Patient name
    patient = models.ForeignKey(Patient, on_delete=models.CASCADE)
    # Convoy name
    convoy = models.ForeignKey(Convoy, on_delete=models.CASCADE)
    # Field to store patient queue number
    queue = models.PositiveIntegerField(default=0) 
    # Date and time when the appointment was created
    created = models.DateTimeField(auto_now_add=True)

    def __str__ (self):
        return f'{self.patient.first_name} {self.patient.last_name}'

    def save(self, *args, **kwargs):
        if not self.queue:
            # Get the latest appointment for this convoy to determine the next queue number
            latest_appointment = Appointment.objects.filter(convoy=self.convoy).order_by('-queue').first()
            new_queue = 1 if latest_appointment is None else latest_appointment.queue + 1
            self.queue = new_queue
            
        super().save(*args, **kwargs)

```

serializer.py

```auto
from rest_framework import serializers
from .models import Detection, Appointment

class DetectionSerializer(serializers.ModelSerializer):
    ticket = serializers.IntegerField()

    class Meta:
        model = Detection
        fields = ['ticket', 'pressure', 'diabetes', 'acc_Diabetes', 'field']

    def create(self, validated_data):
        print("Validated data before pop: ", validated_data)
        ticket = validated_data.pop('ticket')
        print("Ticket value after pop: ", ticket)
        user = self.context['request'].user # Get the logged-in user
        print("User's convoy: ", user.convoy)
        try:
            # Filter appointments based on the user's convoy
            appointment = Appointment.objects.get(convoy=user.convoy, queue=ticket)
            print("Appointment found: ", appointment)
        except Appointment.DoesNotExist:
            raise serializers.ValidationError("Appointment does not exist")

        validated_data['ticket'] = appointment
        print("Validated data before creating Detection: ", validated_data)

        detection = Detection.objects.create(**validated_data)
        print("Detection created: ", detection)

        print(detection.ticket.queue, detection.pressure, detection.diabetes)

        return detection

```

views.py

```auto
class DetectionCreateView(APIView):
    def get_serializer_context(self):
        return {'request': self.request}

    def post(self, request, *args, **kwargs):
        serializer = DetectionSerializer(data=request.data, context=self.get_serializer_context())
        
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

```

urls.py

```auto
from django.urls import path, include
from . import views
# from .views import UserViewSet

app_name= "early"

urlpatterns = [
    path('api/detection/', views.DetectionCreateView.as_view(), name='detection'),
]

```

Postman request

 ![Screenshot (26)](https://us1.discourse-cdn.com/flex026/uploads/djangoproject/original/3X/f/6/f6ad905fc79eca7302ff1c904ec12a46af750360.png)  
 ![Screenshot (27)](https://us1.discourse-cdn.com/flex026/uploads/djangoproject/original/3X/3/d/3de06ea4c136804d58ec430165ee75ce53b8f03d.png)

---

<div class="post-metadata">

**Author:** ![addwebsolution](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/addwebsolution/32/23762_2.png) [@addwebsolution](https://forum.djangoproject.com/u/addwebsolution)\
**Post date:** [November 16, 2023, 1:30pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/2 "2023-11-16T13:30:22Z")

</div>

In `DetectionSerializer` wrap your whole code within try except block like

```auto
class DetectionSerializer(serializers.ModelSerializer):
    .....

    def create(self, validated_data):
        try:
            # Your code here
        except Exception as e:
            print("-----------Exception-------", e)

```

check what print statement prints in your console.

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:34pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/3 "2023-11-16T13:34:23Z")

</div>

my new serilaizer.py

```auto
class DetectionSerializer(serializers.ModelSerializer):
    ticket = serializers.IntegerField()

    class Meta:
        model = Detection
        fields = ['ticket', 'pressure', 'diabetes', 'acc_Diabetes', 'field']

    def create(self, validated_data):
        try:
            print("Validated data before pop: ", validated_data)
            ticket = validated_data.pop('ticket')
            print("Ticket value after pop: ", ticket)
            user = self.context['request'].user # Get the logged-in user
            print("User's convoy: ", user.convoy)
            try:
                # Filter appointments based on the user's convoy
                appointment = Appointment.objects.get(convoy=user.convoy, queue=ticket)
                print("Appointment found: ", appointment)
            except Appointment.DoesNotExist:
                raise serializers.ValidationError("Appointment does not exist")

            validated_data['ticket'] = appointment
            print("Validated data before creating Detection: ", validated_data)

            detection = Detection.objects.create(**validated_data)
            print("Detection created: ", detection)

            print(detection.ticket.queue, detection.pressure, detection.diabetes)

            return detection
        except Exception as e:
            print("-----------Exception-------", e)

```

console

```auto
Validated data before pop: {'ticket': 2, 'pressure': '125/75', 'diabetes': 123}
Ticket value after pop: 2
User's convoy: Test 2
Appointment found:
Patient Test
Validated data before creating Detection: {'pressure': '125/75', 'diabetes': 123, 'ticket': <Appointment: Patient Test>}
Detection created: Patient Test
2 125/75 123
Internal Server Error: /early/api/detection/
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/django/core/handlers/exception.py", line 55, in inner       
    response = get_response(request)
  File "/usr/local/lib/python3.9/site-packages/django/core/handlers/base.py", line 197, in _get_response   
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/views/decorators/csrf.py", line 56, in wrapper_view  
    return view_func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/django/views/generic/base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 469, in handle_exception     
    self.raise_uncaught_exception(exc)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/usr/local/lib/python3.9/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "/app/earlyDetection/views.py", line 16, in post
    return Response(serializer.data, status=status.HTTP_201_CREATED)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/serializers.py", line 555, in data
    ret = super().data
  File "/usr/local/lib/python3.9/site-packages/rest_framework/serializers.py", line 253, in data
    self._data = self.to_representation(self.instance)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/serializers.py", line 522, in to_representation
    ret[field.field_name] = field.to_representation(attribute)
  File "/usr/local/lib/python3.9/site-packages/rest_framework/fields.py", line 915, in to_representation   
    return int(value)
TypeError: int() argument must be a string, a bytes-like object or a number, not 'Appointment'
[16/Nov/2023 15:31:49] "POST /early/api/detection/ HTTP/1.1" 500 102016

```

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:37pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/4 "2023-11-16T13:37:00Z")

</div>

i believe the problem is that my class detectin is returning  
def **str** (self):  
return f’{self.ticket.patient.first\_name} {self.ticket.patient.last\_name}’

Validated data before creating Detection: {‘pressure’: ‘125/75’, ‘diabetes’: 123, ‘ticket’: \<Appointment: Patient Test\>}  
but the ticket expects a number but i don’t know how to fix this issue !!

---

<div class="post-metadata">

**Author:** ![addwebsolution](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/addwebsolution/32/23762_2.png) [@addwebsolution](https://forum.djangoproject.com/u/addwebsolution)\
**Post date:** [November 16, 2023, 1:38pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/5 "2023-11-16T13:38:53Z")

</div>

One more thing I’ve seen just now, In your serializer

```auto
ticket = serializers.IntegerField()

```

and in your models

```auto
ticket = models.ForeignKey(Appointment, on_delete=models.CASCADE)

```

Problem is because of this, You don’t need to give ticket a IntegerField it is a ForeignKey. So even if you pass the id of ticket via postman, it will save it.

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:39pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/6 "2023-11-16T13:39:58Z")

</div>

so what should i change the ticket to ?

do i completely remove this line

```auto
ticket = serializers.IntegerField()

```

---

<div class="post-metadata">

**Author:** ![addwebsolution](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/addwebsolution/32/23762_2.png) [@addwebsolution](https://forum.djangoproject.com/u/addwebsolution)\
**Post date:** [November 16, 2023, 1:40pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/7 "2023-11-16T13:40:48Z")

</div>

yes, you can it is not really needed.

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:41pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/8 "2023-11-16T13:41:43Z")

</div>

i removed it now it is treating the ticket value as primary key which is not, the ticket value refers to the queue inside the Appointment class

```auto
{
    "ticket": [
        "Invalid pk \"2\" - object does not exist."
    ]
}

```

---

<div class="post-metadata">

**Author:** ![addwebsolution](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/addwebsolution/32/23762_2.png) [@addwebsolution](https://forum.djangoproject.com/u/addwebsolution)\
**Post date:** [November 16, 2023, 1:48pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/9 "2023-11-16T13:48:21Z")

</div>

The ticket in your models is a ForeignKey and it will only accept the values of Appointment objects that are created. in your case it is stating that pk with 2 is not created for Appointment table.  
If you ticket have some other functionality then you should work around it and elaborate it more.

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:50pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/10 "2023-11-16T13:50:46Z")

</div>

i need to link the detection with ticket to know the patient and add this data to him.  
each patient gets a queue number from appointment this number exists in appointmnet.queue can i link directly with queue and not the uuid

```auto
class Appointment(models.Model):
    # Unique identifier for each appointment
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False, max_length=36)
    # Patient name
    patient = models.ForeignKey(Patient, on_delete=models.CASCADE)
    # Convoy name
    convoy = models.ForeignKey(Convoy, on_delete=models.CASCADE)
    # Field to store patient queue number
    queue = models.PositiveIntegerField(default=0) 
    # Date and time when the appointment was created
    created = models.DateTimeField(auto_now_add=True)

    def __str__ (self):
        return f'{self.patient.first_name} {self.patient.last_name}'

    def save(self, *args, **kwargs):
        if not self.queue:
            # Get the latest appointment for this convoy to determine the next queue number
            latest_appointment = Appointment.objects.filter(convoy=self.convoy).order_by('-queue').first()
            new_queue = 1 if latest_appointment is None else latest_appointment.queue + 1
            self.queue = new_queue
            
        super().save(*args, **kwargs)

```

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 1:53pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/11 "2023-11-16T13:53:58Z")

</div>

when i check the db the record is added the problem is with the response returned from the api !!!

---

<div class="post-metadata">

**Author:** ![HamzaMa96](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/hamzama96/32/15291_2.png) [@HamzaMa96](https://forum.djangoproject.com/u/HamzaMa96)\
**Post date:** [November 16, 2023, 3:01pm UTC](https://forum.djangoproject.com/t/serializer-saves-to-db-but-returns-500-bad-request/25385/12 "2023-11-16T15:01:13Z")

</div>

I got it to work by doing the following:  
serializer.py

```auto
class DetectionSerializer(serializers.ModelSerializer):
    ticket = serializers.CharField() # Using CharField for queue instead of IntegerField

    class Meta:
        model = Detection
        fields = ['ticket', 'pressure', 'diabetes', 'acc_Diabetes']

    def create(self, validated_data):
        queue = validated_data.pop('ticket')
        user = self.context['request'].user

        try:
            appointment = Appointment.objects.get(convoy=user.convoy, queue=int(queue))
        except (Appointment.DoesNotExist, ValueError):
            raise serializers.ValidationError("Appointment does not exist")

        detection = Detection.objects.create(ticket=appointment, **validated_data)

        return detection

```

views.py

```auto
class DetectionCreateView(APIView):
    def get_serializer_context(self):
        return {'request': self.request}

    def post(self, request, *args, **kwargs):
        serializer = DetectionSerializer(data=request.data, context=self.get_serializer_context())
        
        if serializer.is_valid():
            serializer.save()
            print(f'response: {serializer.data}')
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

```