Django Models - insert foreign key values using Shell

Question

I am trying to save values for my Models through Django Shell . I am beginner in Django. I have crated three models. I inserted values in models one by one.i created Dept first and inserted all Dept Values.Created Student and inserted all student related values. Now i am trying to insert values in course which contains two foreign key studentId and dept id . How to insert values for Student model using Django Shell.

    # -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models

# Create your models here.
from django.db import models
from django.utils import timezone

class Student(models.Model):
    studentId = models.AutoField(primary_key=True)
    firstname = models.CharField(max_length=50)
    middlename = models.CharField(max_length=1)
    lastname = models.CharField(max_length=50)
    city = models.CharField(max_length=200)
    registe_dt = models.DateTimeField(default=timezone.now())
    def __str__(self):
        return '%s %s %s' % (self.studentId, self.firstname,self.city)


class Dept(models.Model):
    deptId = models.AutoField(primary_key=True)
    deptName = models.CharField(max_length=200)
    def __str__(self):
        return '%s %s' % (self.deptId, self.deptName)

class Course(models.Model):
    courseId=models.AutoField(primary_key=True)
    courseName=models.CharField(max_length=100)
    student = models.ManyToManyField(Student)
    dept = models.ForeignKey(Dept,on_delete=models.CASCADE)
    def __str__(self):
        return '%s %s %s %s' % (self.courseId, self.courseName,self.student.primary_key,self.dept.primary_key)

Thank you for helping Jordan

Answer 1

You can insert the student and dept instances directly when inserting foreign key values:

student = Student.objects.last()
dept = Dept.objects.last()

course = Course.objects.create(courseName="My course", student=student, dept=dept)

.last() is the last one created, but you can get the instances however you like.

---

Also, you don't need to manually create primary keys. Django does it automatically for you. Each instance of a model has a pk value automatically assigned. That is if you don't need a differently named primary key. So the __str__ method in Course could be:

def __str__(self):
        return '%s %s %s %s' % (self.courseId, self.courseName,self.student.pk,self.dept.pk)

Answer 2

I tried following syntax but unable to insert data. if i try to create null object like c1 = Course() and try to use that object it still gives error.

s1 = Student(firstname='test',middlename='M',lastname='test',city='test') s1.save() for dept: d1 = Dept(deptName='Computer') d1.save() for course: course = Course.objects.create(courseName='Java',student=s1,dept=d1)

Resulted in ""ValueError: "" needs to have a value for field "courseId" before this many-to-many relationship can be used."