Django-REST-Framework validate fails: "this field is required" - django

Question

some context here... I have a Room object that has a list of pictures. Right now I'm stuck at the POST method (create a new room with pictures). But I keep getting the validation error "this field is required".
model
class Room(models.Model):
CONDO = 'condo'
HOUSE = 'house'
OTHER = 'other'
ROOM_TYPES = [(CONDO, 'condo'), (HOUSE, 'house'), (OTHER, 'other')]
name = models.CharField(max_length=50)
price = models.IntegerField()
type = models.CharField(max_length=5, choices=ROOM_TYPES)
location = models.CharField(max_length=100)
info = models.TextField(max_length=500, blank=True)
owner = models.ForeignKey(CustomUser, on_delete=models.CASCADE, related_name='listings', null=True)
start_date = models.DateField()
end_date = models.DateField()
is_available = models.BooleanField(default=True)
include_utility = models.BooleanField(default=False)
allow_pet = models.BooleanField(default=False)
include_parking = models.BooleanField(default=False)
include_furniture = models.BooleanField(default=False)
class RoomPicture(models.Model):
room = models.ForeignKey(Room, on_delete=models.CASCADE, related_name='images', null=True)
image = models.ImageField(upload_to='images/', blank=True, null=True)
class Meta:
unique_together = ['room', 'image']
serializer
class RoomPictureSerializer(serializers.ModelSerializer):
class Meta:
model = RoomPicture
fields =['id','image']
class RoomSerializer(serializers.ModelSerializer):
# images = serializers.ImageField(upload_to='images/', blank=True, null=True)
images = RoomPictureSerializer(many=True)
class Meta:
model = Room
fields = ['id', 'owner', 'name', 'price', 'type', 'location', 'info',
'start_date', 'end_date', 'is_available' , 'include_utility' ,'allow_pet',
'include_parking', 'include_furniture', 'images']
def create(self, validated_data):
images_data = validated_data.pop('images')
room = Room.objects.create(**validated_data)
for image_data in images_data:
RoomPicture.objects.create(room=room, image=image_data["image"])
return room
views
def convert(image):
dict = {}
# dict['id'] = 0
dict['image'] = image
return dict
class RoomViewSet(viewsets.ModelViewSet):
# permission_classes = [
# permissions.IsAuthenticated,
# ]
parser_classes = (MultiPartParser, FormParser)
serializer_class = RoomSerializer
queryset = Room.objects.all()
def create(self, request):
# converts querydict to original dict
dict_data = dict((request.data).lists())
dict_data['images'] = list(map(convert, dict_data['images']))
print(request.data)
query_dict = QueryDict('', mutable=True)
query_dict.update(MultiValueDict(dict_data))
print(query_dict)
serializer = RoomSerializer(data=query_dict)
if serializer.is_valid():
serializer.save(owner=request.user)
return Response(serializer.data)
else:
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
What I don't understand is that in my view, I explicitly passed in query_dict which has an 'images' key. But for some reason the validator does not recognize it.
so the request.data looks like this
<QueryDict: { 'name': [ 'The Building'], 'price': [ '900'], 'type': [ 'condo'], 'location': [ '100 Trump Rd'], 'info': [ '1 bedroom + 1 bath / share kitchen & living room'], 'start_date': [ '2021-09-01'], 'end_date': [ '2021-12-31'], 'is_available': [
'true'], 'include_utility': [ 'true'], 'include_parking': [ 'true'], 'include_furniture': [ 'true'], 'allow_pet': [ 'true'], 'images': [<InMemoryUploadedFile: Phillip-Square-Blair-House-Conference-Room.jpg (image/jpeg)>,
<InMemoryUploadedFile: Phillip-Square-Blair-House-Gym.jpg (image/jpeg)>]}>
and the tuned query_dict looks like this
<QueryDict: {'name': ['The Building'], 'price': ['900'], 'type': ['condo'], 'location': ['100 Trump Rd'], 'info': ['1 bedroom + 1 bath / share kitchen & living room'], 'start_date': ['2021-09-01'], 'end_date': ['2021-12-31'], 'is_available': ['true'], 'include_utility': ['true'], 'include_parking': ['true'], 'include_furniture': ['true'], 'allow_pet': ['true'], 'images': [{'image': <InMemoryUploadedFile: Phillip-Square-Blair-House-Conference-Room.jpg (image/jpeg)>}, {'image': <InMemoryUploadedFile: Phillip-Square-Blair-House-Gym.jpg (image/jpeg)>}]}>
whether I pass in serializer = RoomSerializer(data=request.data) or serializer = RoomSerializer(data=query_dict) I always get the same error...
Can somebody help me? Thanks in advance!

Answer 1

The default ModelSerializer implementation does not allow nested serializer data so serializer.is_valid() will return false hence the error.
Even using the drf_writable_nested module doesn't work for it as well.
Based on what you're trying to do, there are 3 options that I can advise:
Write your serializer explicitly with serializers.Serializer though, that will be a lot of code but, it'll satisfy the nesting.
Create separate views and serializers for the RoomPicture model. This way, on your client-side, you'll initially create the Room object then upload the images afterwards.
If you have a specific amount of images for the Room object, you can add image fields to the Room model e.g
class Room(models.Model):
...
image1 = models.ImageField(upload_to='images/', blank=True, null=True)
image2 = models.ImageField(upload_to='images/', blank=True, null=True)
image3 = models.ImageField(upload_to='images/', blank=True, null=True)
...
#property
def images(self):
images_list = []
image_fields = [self.image1, self.image2, self.image3]
for image_count, image_field in enumerate(image_fields, start=1):
if image_field:
image_dict = {'path': image_field.url, 'count': image_count}
images_list.append(image_dict)
return images_list
If the images can be more than 5, you might want to use option 2.
You'll have to add images to your RoomSerializer as a ReadOnlyField(), it'll serialize the data as a list of objects just like what you'll get from using FK.
You'll be able to create and update your Room data with the images altogether.
To delete a particular image, just set the field as null. That's why I added count to the image_dict data to help know which image to update from the client-side.
You should also install django-cleanup to help delete the previous image after an update has been made to any of the image fields.