new_contents: from django.core.management.base import BaseCommand
  
  from contacts.models import Book, Contact, ContactField
  
  class Command(BaseCommand):
  
      def handle(self, *args, **kwargs):
          book = Book.objects.get(id=1)
          for n in range(40):
              contact = Contact.objects.create(
                  book=book,
                  name='Test {}'.format(n),
              )
              for m in range(10):
                  ContactField.objects.create(
                      contact=contact,
                      kind='email',
                      label='Test {}'.format(m),
                      value='pjj+{}@pjj.pjj'.format(m),
                  )
  
subject: Add a command to populate test data.