Slightly modified decorator from https://adamj.eu/tech/2022/10/13/dry-run-mode-for-data-imports-in-django/

dry-run-example.py

import argparse
import csv
from collections.abc import Generator
from contextlib import contextmanager, closing
from io import TextIOWrapper
from typing import Any

from django.core.management.base import BaseCommand
from django.db import transaction

from example.core.models import Author, Book


class Command(BaseCommand):
    help = "Import books from a CSV"

    def add_arguments(self, parser):
        parser.add_argument(
            "--write",
            action="store_true",
            default=False,
            help="Actually edit the database",
        )
        parser.add_argument("file", type=argparse.FileType())

    def handle(
        self, *args: Any, file: TextIOWrapper, write: bool, **kwargs: Any
    ) -> None:
        if not write:
            self.stdout.write("In dry run mode (--write not passed)")

        books_created = 0
        authors_created = 0

        with closing(file), atomic(commit=write):
            csvfile = csv.reader(file)

            header = next(csvfile)
            if header != ["Title", "Author"]:
                self.stdout.write("Unexpected header row, should be “Title,Author”")
                raise SystemExit(1)

            for title, author_name in csvfile:
                author, created = Author.objects.get_or_create(name=author_name)
                if created:
                    authors_created += 1

                book, created = Book.objects.get_or_create(
                    title=title,
                    author=author,
                )
                if created:
                    books_created += 1

        if write:
            prefix = "Created"
        else:
            prefix = "Would create"
        self.stdout.write(
            f"{prefix} {books_created} books and {authors_created} authors."
        )


class DoRollback(Exception):
    pass


@contextmanager
def atomic(*, commit: bool) -> Generator[None, None, None]:
    try:
        with transaction.atomic():
            yield
            if not commit:
                raise DoRollback()
    except DoRollback:
        pass