How to fix Field defines a relation with the model 'auth.User', which has been swapped out

Question

I am trying to change my user model to a custom one. I do not mind dropping my database and just using a new one, but when I try it to run makemigrations i get this error

bookings.Session.session_client: (fields.E301) Field defines a relation with the model 'auth.User', which has been swapped out.
        HINT: Update the relation to point at 'settings.AUTH_USER_MODEL'.

booking/views.py

from django.shortcuts import render, get_object_or_404
from django.http import HttpResponse, HttpResponseRedirect
from bookings.models import Session
from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import User

# Create your views here.

def book(request, Session_id):
    lesson = get_object_or_404(Session, pk=Session_id)
    try:
        client = request.user.id
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'booking/details.html', {
            'lesson': lesson,
            'error_message': "You need to login first",
        })
    else:
        lesson.session_client.add(client)
         lesson.save()
     return HttpResponseRedirect("")

settings.py

INSTALLED_APPS = [
    #Custom apps
    'mainapp.apps.MainappConfig',
    'bookings.apps.BookingsConfig',

    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

AUTH_USER_MODEL = 'mainapp.CustomUser'

bookings/models.py

from django.db import models
from django.contrib.auth.models import User

# Create your models here.
class Session(models.Model):
    session_title = models.CharField(max_length=300)
    session_time = models.DateTimeField("Time of session")
    session_difficulty = models.CharField(max_length=200)
    session_duration = models.IntegerField() 
    session_description = models.TextField()
    session_client = models.ManyToManyField(User, blank=True) 

    def __str__(self):
        return self.session_title   

I'm trying to change the user model to abstractuser.

Answer 1

include the following at in views.py

from django.conf import settings
User = settings.AUTH_USER_MODEL

and remove from django.contrib.auth.models import User

Answer 2

The problem is this line in booking/models.py:

session_client = models.ManyToManyField(User, blank=True) 

You have a ManyToManyField to User, but you have set a different User model.

So in that field remove the import of User, add

from django.conf import settings

and change the model line to

session_client = models.ManyToManyField(settings.AUTH_USER_MODEL, blank=True)

Edit: there's another similar problem in views.py, as HenryM notes.

Answer 3

Change:

from django.contrib.auth.models import User

To:

from django.contrib.auth import get_user_model
User = get_user_model()

Answer 4

because in settings.py is defined

AUTH_USER_MODEL = 'user.User'

instead of auth.User I added user.User

user = models.ForeignKey('user.User', on_delete=models.CASCADE)

Answer 5

I had the same error, Change model fields from this:

user = models.ForeignKey(to=User, on_delete=models.CASCADE)

to this:

user = models.ForeignKey(to=MyUser, on_delete=models.CASCADE)

MyUser is your custom user model