create and add many to many field in django

1. In your Django model, define the ManyToManyField:

class ModelName(models.Model):
    related_models = models.ManyToManyField(RelatedModel)

1. Create and apply a migration to add the ManyToManyField:

python manage.py makemigrations
python manage.py migrate

1. Use the ManyToManyField in your code to add related instances:

instance.related_models.add(related_instance)

1. To access related instances:

related_instances = instance.related_models.all()