I am new to Django and have trouble making django-rest-framework API for post, inheriting APIView. I'm using a serializer, that inherits djangos ModelSerializer. I face NOT NULL constraint failed: accounts_personalcolor.user_id error whenever I try saving the serializer or model object.

color.js posts image using Django rest framework as follows.

function PersonalColorScreen({navigation,route}) {
    const {image} = route.params;
    console.log('uri is', image.uri);
    const [userToken, setUserToken] = React.useState(route.params?.userToken);

    const requestHeaders = {
        headers: {
            "Content-Type": "multipart/form-data"
        }
    }
    // helper function: generate a new file from base64 String
    //convert base64 image data to file object to pass it onto imagefield of serializer.
    //otherwise, serializer outputs 500 Internal server error code

    const dataURLtoFile = (dataurl, filename) => {
    const arr = dataurl.split(',')
    const mime = arr[0].match(/:(.*?);/)[1]
    const bstr = atob(arr[1])
    let n = bstr.length
    const u8arr = new Uint8Array(n)
    while (n) {
      u8arr[n - 1] = bstr.charCodeAt(n - 1)
      n -= 1 // to make eslint happy
    }
    return new File([u8arr], filename, { type: mime })
  }
  //random number between 0-9
  function getRandomInt(max) {
    return Math.floor(Math.random() * max);
  }
  
  // generate file from base64 string
  const file = dataURLtoFile(image.uri, `${getRandomInt(10)}.png`)
  const formData= new FormData();
  formData.append('img',file,file.name);

  console.log(file.name);
    //axios post request to send data
    // axios.post('http://localhost:8000/accounts/personalcolor/',  formData,requestHeaders)
    //multipartparser
    axios.post('http://localhost:8000/accounts/personalcolor/', formData, requestHeaders)
    .then(res => {
        console.log(res);
        if (res.data === 'upload another image') {
            setimageError('upload another image');
        } else {
            // signUp(userToken);
            let color;
            switch (res.data){
                case ('spring'):
                    color = 'spring';
                    break;
                case ('summer'):
                    color = 'summer';
                    break;
                case ('fall'):
                    color = 'fall';
                    break;
                case ('winter'):
                    color = 'winter';
                    break;
            }
        }
        })
    .catch(err => {
        console.error(err.response.data)
    })

view.py handles the image posted. I tried #1 but it did not work. So I tried #2, or #3 instead and they return the same error saying NOT NULL constraint failed: accounts_personalcolor.user_id. I thought saving the serializer or model object creates id(Autofield)automatically and I don't understand why I face this error.

views.py

@api_view(['POST'])
def personalcolor(request):

    # 1
    image=request.FILES['img']
    personal_color=Personalcolor()
    personal_color.img=image
    personal_color.save()

    # 2
    image=request.FILES['img']
    personal_color=Personalcolor.objects.create(img=image)
    personal_color.save()

    # 3
    serializer = ColorSerializer(data=request.data)
    # validation of input data
    if serializer.is_valid():
        serializer.save()
    else:
        return Response(serializer.errors, status = status.HTTP_400_BAD_REQUEST)

model.py

class Personalcolor(models.Model):
    objects = models.Manager()
    img = models.ImageField('personal_img',upload_to="personalcolor/", blank=True)

serializer.py

class ColorSerializer(serializers.ModelSerializer):
   class Meta:
      model = Personalcolor
      fields = ['img']

As mentioned above, executing the code returns django.db.utils.IntegrityError: NOT NULL constraint failed: accounts_personalcolor.user_id. Any help would be greatly appreciated.

CodePudding user response：

Set null to true in your img field like:

img = models.ImageField('personal_img',upload_to="personalcolor/", blank=True, null=True)

Then in your migrations folder within the app where the Personalcolor model is located, delete all of the files that look like 000*_initial.py

Then run makemigrations and migrate