Is it possible to switch to a through model in one release?

Assume I have those Django models:

class Book(models.Model):
    title = models.CharField(max_length=100)

class Author(models.Model):
    name = models.CharField(max_length=100)
    books = models.ManyToManyField(Book)

I already have a production system with several objects and several Author <-> Book connections.

Now I want to switch to:

class Book(models.Model):
    title = models.CharField(max_length=100)

class BookAuthor(models.Model):
    book = models.ForeignKey(Book, on_delete=models.CASCADE)
    author = models.ForeignKey("Author", on_delete=models.CASCADE)
    impact = models.IntegerField(default=1)

    class Meta:
        unique_together = ("book", "author")

class Author(models.Model):
    name = models.CharField(max_length=100)
    books = models.ManyToManyField(Book, through=BookAuthor)

If I do this Migration:

from django.db import migrations

def migrate_author_books(apps, schema_editor):
    Author = apps.get_model('yourappname', 'Author')
    BookAuthor = apps.get_model('yourappname', 'BookAuthor')

    for author in Author.objects.all():
        for book in author.books.all():
            # Create a BookAuthor entry with default impact=1
            BookAuthor.objects.create(author=author, book=book, impact=1)

class Migration(migrations.Migration):

    dependencies = [
        ('yourappname', 'previous_migration_file'),
    ]

    operations = [
        migrations.RunPython(migrate_author_books),
    ]

then the loop for book in author.books.all() will access the new (and empty) BookAuthor table instead of iterating over the existing default table Django created.

How can I make the data migration?

The only way I see is to have two releases:

1. Just add the new BookAuthor model and fill it with data, but keep the existing one. So introducing a new field and keeping the old one. Also change every single place where author.books is used to author.books_new
2. Release + migrate on prod
3. Remove author.books and rename books_new to books. Another migration, another release.

Isn't there a simpler way?

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