NOT NULL constraint failed: shipping_ship.user_id Django - django

Question

So I'm working on a shipping website with the django rest framework. The website brings two to four people together so they can easily ship their goods together at the same time. But I'm facing a major stumbling block on the views where user book a shipping the code is below.
models.py
from django.db import models
from django.contrib import get_user_model
User = get_user_model()
class Container(models.Model):
container_type = models.Charfield(max_length = 30, blank=False, null = False)
max_users = models.IntegerField()
price = models.DecimalField(max_digits=10, decimal_places =2, default=0, blank=True, null=True)
users = models.ManyToManyField(User)
class Ship(models.Model):
container = models.ForeignKey(Container, related_name='cont', on_delete=models.CASCADE)
user = models.ForeignKey(User, related_name='shipper', on_delete=models.CASCADE)
location = (
('France', 'France'),
)
from_location = models.CharField(max_length=30, choices=location, blank=False, null=False)
to_location = (
('Lagos', 'Lagos'),
('Abuja', 'Abuja'),
('Abeokuta', 'Abeokuta'),
('Osun', 'Osun'),
)
to_location = models.CharField(max_length=30, choices=to_location, blank=False, null=False)
date_leaving = models.DateField(auto_now=False)
price = models.DecimalField(max_digits=10, decimal_places=2, default=0, blank=True, null=True)
def __str__(self):
return self.user
then my serializer.py file
from rest_framework import serializers
from .models import Container, Ship
class ContainerSerializer(serializers.ModelSerializer):
class Meta:
model = Container
fields = '__all__'
class MiniContainerSerializer(serializers.ModelSerializer):
class Meta:
model = Container
fields =['container_type', 'price']
class ShipSerializer(serializers.ModelSerializer):
class Meta:
model = Ship
fields = '__all__'
read_only_fields = ('user', 'price')
class MiniShipSerializer(serializers.ModelSerializer):
class Meta:
model = Ship
fields = ['container', 'from_location', 'to_location']
and now my views.py file which I have issues with
from django.shortcuts import render
from django.shortcuts import get_object_or_404
from rest_framework.generics import ListCreateAPIView, CreateAPIView, ListAPIView, RetrieveUpdateDestroyAPIView, RetrieveAPIView
from .serializers import ContainerSerializer, MiniContainerSerializer, ShipSerializer, MiniShipSerializer
from rest_framework import permissions, status
from rest_framework.response import Response
from .models import Container, Ship
class ShipAPI(ListCreateAPIView):
serializer_class = ShipSerializer
def get_queryset(self):
user = self.request.user
queryset = Ship.objects.filter(user=user)
return queryset
def Book_shipping(self, request, *args, **kwargs):
user = request.user
container = get_object_or_404(Container, pk=request.data['container'])
if container.users.count() >= container.max_users:
return Response('container already full')# here i'm trying to set limits so the users joining each container won't surpass the max users.
cont = container(users=user)
cont.save()
from_location = (request.data['from_location'])
to_location = (request.data['to_location'])
date_leaving = int(request.data['date_leaving'])
price = container.price / container.max_users
cart = Ship(container=container, user=user, from_location=from_location, to_location=to_location, date_leaving=date_leaving, price=price)
cart.save()
serializer = ShipSerializer(cart)
data ={'message': 'shipping successfully created',
'data':serializer.data}
return Response(data=data, status=status.HTTP_201_CREATED)
and then after testing the endpoint it returns this error:
IntegrityError at /Shipping/Ship/
NOT NULL constraint failed: shipping_ship.user_id
I've tried debugging and looking at it over and over again can someone please help me? Thanks in advance. And yes I've tried deleting migrations and the database.

Answer 1

As your Container model have a ManyToMany relationship with the User model.
So it may not work like cont = container(users=user)
For me it worked like this:
cont = container.users.add(user)
cont.save()