Not able to update models ManyToMany relationship django. getting an error saying the models field has not been defined

Question

i'm just confused or tired on this one. when this code runs it doesn't always remove or add, and when it does it will not update the like count. As i see the code, when the user is found in the liked value it should remove the user and decrease the likes and visa versa, it does not seem to do that. I also only seem to be able to have 1 like across all pictures, so i would have to remove one like and add to another, again this seems to all happen randomly.

    def liked_pic(request):
        pdb.set_trace()
        if request.method == 'POST':
            pic = Pictures.objects.get(id=request.POST.get('pic_id'))
            user = UserModel.objects.get(email=request.user)
            liked = Pictures.objects.filter(likes=user).exists()
            print(pic.likes, liked)
            if liked:
                pdb.set_trace()
                pic.likes.remove(user)
                pdb.set_trace()
                pic.save()
            if not liked:
                pdb.set_trace()
                pic.likes.add(user)
                pic.save()
            picturecount = Pictures.objects.filter(likes).count()
            data = {'json_pic_id': pic.id,'likes': picturecount, 'user':liked}
            return JsonResponse(data)
            return HttpResponseRedirect('home')


class Pictures(models.Model):
    image = models.ImageField(upload_to='static/dataset/')
    author = models.ForeignKey(UserModel,on_delete=models.CASCADE)
    likes = models.ManyToManyField(UserModel,default=False,blank=True,related_name='likes')       
    description = models.CharField(default=False,max_length=200)


class UserModel(AbstractBaseUser,PermissionsMixin):
    sys_id = models.AutoField(primary_key=True, blank=True)
    email = models.EmailField(max_length=127, unique=True, null=False, blank=False)
    username = models.CharField(max_length=30, unique=True)

    is_staff = models.BooleanField(default=False)
    is_active = models.BooleanField(default=True)

    objects = MyUserManager()

    USERNAME_FIELD = "email"
    # REQUIRED_FIELDS must contain all required fields on your User model,
    # but should not contain the USERNAME_FIELD or password as these fields will always be prompted for.
    REQUIRED_FIELDS = ['is_staff']








    pdb trace-----------------

    System check identified no issues (0 silenced).
    January 06, 2020 - 09:50:49
    Django version 3.0, using settings 
    Starting development server at http://127.0.0.1:8000/
    Quit the server with CTRL-BREAK.
    **accounts.UserModel.None False**
    (Removed computer path information)
    **-> pic.likes.add(user)**
    (Pdb) continue
    [06/Jan/2020 09:51:05] "POST /liked/ HTTP/1.1" 200 44
    [06/Jan/2020 09:51:23] "GET /home/ HTTP/1.1" 200 3141
    [06/Jan/2020 09:51:23] "GET /media/static/dataset/00000016.png HTTP/1.1" 200 184935
    **accounts.UserModel.None True**
    (Removed computer path information)
    -> **pic.likes.remove(user)**
    (Pdb)
    (Pdb) continue





    -> pic.save()
    (Pdb) continue
    [06/Jan/2020 09:51:52] "POST /liked/ HTTP/1.1" 200 44

Answer 1

Without knowing more details about the app, I think your logic is slightly off (obviously otherwise you wouldn't have a problem). If you step through your liked_pic code you're doing the following:

1. Get me the picture the person liked
2. Get me the logged in user
3. Get me ALL pictures the user liked
4. If the user liked ANY picture, then remove the like from this one picture
5. If the user has ZERO likes, then add the like to the current picture

I think you might need to change your liked line to something like this:

liked = Pictures.objects.filter(id=request.POST.get('pic_id'), likes=user).exists()

More specifically, you need to check if the user has liked that one picture, not all pictures. Hope that helps.