from django.db import models

                    #DataFlair #DjangoTutorials
                    # Create your models here.
                    class Customer(models.Model):
                        name = models.CharField(max_length=255)

                    class Vehicle(models.Model):
                        name = models.CharField(max_length=255)
                        customer = models.OneToOneField(
                            Customer,
                            on_delete=models.CASCADE,
                            related_name='vehicle'
                        )

                    

Model

                    class Owner(models.Model):

                        #...
                        name = models.CharField(max_length=255)
                    class Car(models.Model):

                        #...
                        name = models.CharField(max_length=255)
                        owner = models.OneToOneField(
                            Owner,
                            on_delete=models.CASCADE,
                            related_name='car'
                        )

                    

Store Records:

                    car = Car.objects.get(id=1)
                    owner  = Owner.objects.get(id=1)
                    # Create relation between Owner and Car.
                    owner.car = car
                    owner.car.save()
                    # Create relation between Car and Owner.
                    car.owner = owner
                    car.save()

                    

Retrieve Records:

                    # Get Owner Car
                    owner.car
                    # Get Car Owner
                    car.owner;

                    

                     from django.db import models

                    #DataFlair #DjangoTutorials
                    # Create your models here.
                    class Customer(models.Model):
                        name = models.CharField(max_length=255)

                    class Vehicle(models.Model):
                        name = models.CharField(max_length=255)
                        customer = models.ForeignKey(
                            Customer,
                            on_delete=models.CASCADE,
                            related_name='Vehicle'
                        )

                        

Models:

                        class Thief(models.Model):

                            # ...
                            name = models.CharField(max_length=255)
                        class Car(models.Model):

                            # ...
                            name = models.CharField(max_length=255)
                            thief = models.ForeignKey(
                                Thief,
                                on_delete=models.CASCADE,
                                related_name='cars'
                            )

                            

Store Records:

                            thief  = Thief.objects.get(id=1)
                            car1 = Car.objects.get(id=1)
                            ...
                            # Create relation between Thief and Car.
                            thief.cars.add(car1,car2, car3)
                            # Create relation between Car and Thief.
                            car.thief = thief
                            car.save()
                            # When we creating new car : 
                            car = Car(name = 'test name', thief=thief)
                            car.save()

                            

Retrieve Records:

                            # Get Thief Car  
                              thief.cars.all()
                              # Get Car Thief
                              car.thief
                              

                     from django.db import models

                      # Create your models here.
                      #DataFlair #Many to Many Relationship
                      class Worker(models.Model):
                          name = models.CharField(max_length=255)

                      class Machine(models.Model):
                          name = models.CharField(max_length=255)
                          worker = models.ManyToManyField(
                              Worker,
                              related_name='Machine'
                          )

                          

Models:

                          class Driver(models.Model):

                              # ...
                              name = models.CharField(max_length=255)
                          class Car(models.Model):

                              # ...
                              name = models.CharField(max_length=255)
                              drivers = models.ManyToManyField(
                                  Driver,
                                  related_name='cars'
                              )

                              

Store Records:

                              # Create relation between Driver and Car.
                              driver  = Driver.objects.get(id=1)
                              car1 = Car.objects.get(id=1)
                              car2 = Car.objects.get(id=2)
                              driver.cars.add(car1,car2)
                              # Create relation between Car and Driver.
                              car = Car.objects.get(id=1)
                              driver1  = Driver.objects.get(id=2)
                              driver2  = Driver.objects.get(id=3)

                              car.drivers.add(driver1, driver2)

                              

Retrieve Records:

                              # Get Driver Car
                              driver.cars.all()
                              # Get Car Drivers
                              car.drivers.all()

                              

we have 3 models (Man, Woman and Car), and 3 tables (men, women and cars).

The Car table should store the Buyer ID and the Buyer table should store the relation between ID and Type.

Models

                     from django.contrib.contenttypes.fields import GenericForeignKey
                    from django.contrib.contenttypes.fields import GenericRelation
                    from django.contrib.contenttypes.models import ContentType
                    class Car(models.Model):
                        # ...
                        name = models.CharField(max_length=255)
                        content_type = models.ForeignKey(ContentType,         on_delete=models.CASCADE)
                        object_id = models.PositiveIntegerField()
                        content_object = GenericForeignKey()
                    class Woman(models.Model):
                        # ...
                        name = models.CharField(max_length=255)
                        cars = GenericRelation(Car)
                    class Man(models.Model):
                        # ...
                        name = models.CharField(max_length=255)
                        cars = GenericRelation(Car)

                              

Store Records:

                                 man = Man.objects.get(id=1)
                                woman = Woman.objects.get(id=1)
                                # Create relation between buyer (Man/Woman) and Car.
                                car = Car.objects.get(id=1)
                                woman.cars.add(car)
                                # Create relation between Car and buyer (Men/Women).
                                man = Man.objects.get(id=1)
                                woman = Woman.objects.get(id=1)
                                c = Car(name = 'test name',content_object=man)
                                c.save()
                                c = Car(name = 'test name',content_object=woman)
                                c.save()

                              

Retrieve Records:

                                # Get buyer (Man/Woman) Cars
                                man.cars.all()
                                woman.cars.all()
                                # Get Car buyer (Man and Woman)
                                car.content_object