postman only showing "This field is required" to ManyToMany field in django - django

Question

I have 2 models - Module and Room. A module can have zero or multiple rooms and a room can be added into multiple modules. So, there is a simple many-to-many relationship between them.
When I use post request, raw-data works, but not form-data.
module/models.py -
class Module(models.Model):
module_id = models.AutoField(primary_key=True)
title = models.CharField(max_length=100)
desc = models.TextField()
room_list = models.CharField(max_length = 100, blank=True)
rooms = models.ManyToManyField(Rooms, blank=True)
rooms/models.py -
class Rooms(models.Model):
room_id = models.AutoField(primary_key=True)
title = models.CharField(max_length=100)
level = models.CharField(max_length=100)
desc = models.TextField()
module/serializers.py -
class ModuleSerializer(serializers.ModelSerializer):
rooms = RoomSerializer(many=True)
class Meta:
model = Module
fields = '__all__'
def create(self, validated_data):
rooms_data = validated_data.pop('rooms')
module = Module.objects.create(**validated_data)
for data in rooms_data:
room = Rooms.objects.get(**data)
module.rooms.add(room)
return module
def update(self, instance, validated_data):
# Updating rooms
rooms_data = validated_data.get('rooms')
instance.rooms.clear()
for room_data in rooms_data:
room = Rooms.objects.get(**room_data)
instance.rooms.add(room)
# Updating other fields
fields = [
'title',
'desc',
'thumbnail',
'is_deleted',
]
for field in fields:
setattr(instance, field, validated_data[field])
instance.save()
return instance
rooms/serialier.py -
class RoomSerialize(serializers.ModelSerializer):
room_id = serializers.IntegerField()
class Meta:
model = Rooms
fields = "__all__"
module/views.py -
class add_module(APIView):
def post(self, request, format=None):
# Adding the rooms to module from room_list
new_request = request.data.copy()
room_list=[]
if 'room_list' in new_request:
room_list_data = list(new_request['room_list'].split(" "))
for room in room_list_data:
room_object = Rooms.objects.get(room_id=room)
room_serializer = RoomSerializer(room_object)
room_list.append(room_serializer.data)
new_request.update({'rooms':room_list})
# creating the module
module_serializer = ModuleSerializer(data=new_request)
if module_serializer.is_valid():
module_serializer.save()
return Response(module_serializer.data['module_id'])
return Response(module_serializer.errors)
POST request body for updating a module in POSTMAN -
{
"module_id": 2,
"room_list": "1 2",
"title": "4",
"desc": "22",
}
Pls notice that while taking input of ManyToMany field - "rooms", I'm taking a string "room_list" as input that contains all the room_ids to be included. This works perfectly fine when I take input as raw-data in postman, but when I use form-data, it shows
{
"rooms": [
"This field is required."
]
}
What to do?

Answer 1

First of all, serializer fields with (many=True) create nested objects.
If you input data with Rooms as already serialized, then it means that you create other Rooms instances. It will be shown with if module_serializer.is_valid(): part. Therefore, if you intended to implement as just link already instantiated Rooms to Module, it's better to make it as primary key list.
Here are my example codes.
class ModuleSerializer(serializers.ModelSerializer):
rooms = RoomSerializer(many=True, read_only=True)
def create(self, validated_data):
rooms_data = validated_data['room_list']
module = Module.objects.create(**validated_data)
for data in rooms_data.split(' '):
room = Rooms.objects.get(room_id=data)
module.rooms.add(room)
return module
def update(self, instance, validated_data):
# Updating rooms
rooms_data = validated_data.get('rooms')
instance.rooms.clear()
for room_data in rooms_data:
room = Rooms.objects.get(**room_data)
instance.rooms.add(room)
# Updating other fields
fields = [
'title',
'desc',
'thumbnail',
'is_deleted',
]
for field in fields:
setattr(instance, field, validated_data[field])
instance.save()
return instance
class Meta:
model = Module
fields = '__all__'
class AddModule(APIView):
def post(self, request, format=None):
# creating the module
module_serializer = ModuleSerializer(data=request.data)
if module_serializer.is_valid():
module_serializer.save()
return Response(module_serializer.data['module_id'])
return Response(module_serializer.errors)
Any other parts are same as yours. Regardless of whether data are sent by form-data or json raw data, results are same as below.