The django has already provided the way to use SQL, I don't think this is needed.
----- Original Message ----- From: "Noam" <[EMAIL PROTECTED]> To: "Django users" <django-users@googlegroups.com> Sent: Thursday, July 05, 2007 2:40 AM Subject: An idea on DB migration > > > Hello, > > I have an idea on how DB migration can work in Django. It's very > simple, it will allow the programmer to do anything he wants in the > migration, and he will have to learn almost nothing in order to > migrate the DB. The drawback is that it's not very efficient, which > means that it will probably work only for small to medium databases - > but I think that most Django sites are like this. If you have a bigger > site, you will have to use SQL. > > My idea is this: create a tool which will create a script which will > migrate the DB. The user will then edit the script as he likes, and > run it to create a new DB with the migrated data. If the result is not > what he wanted, he will edit the script again and run it again. > > For example, say that I have a directory with the old site (and old > models) and a directory with the new site. The only difference between > them is that I renamed the field store.Book.name to > store.Book.book_name. I will run "django-admin.py migrate oldsitedir > newsitedir". This will create a file which will look like this: > > ============================= > #!/usr/bin/env python > > from django.db import ... > > class old_settings: > DATABASE_ENGINE = 'mysql' > DATABASE_NAME = 'store_3' > ... > > class new_settings: > DATABASE_ENGINE = 'mysql' > DATABASE_NAME = 'store_4' > ... > > old_connection = make_connection_from_settings(old_settings) > new_connection = make_connection_from_settings(new_settings) > > # Old models > > class old: > class auth: > class User(models.Model): > _connection = old_connection # or whatever will be needed > > username = models.CharField(unique=True, maxlength=30) > ... > > class store: > class Book(models.Model): > _connection = old_connection > > name = models.CharField() > ... > > # New models > > class new: > ... > class store: > class Book(models.Model): > _connection = old_connection > > book_name = models.CharField() > ... > > # Migration function > > def migrate(): > drop_tables_in_new_db_and_sync_it() > > # Migrate auth.User > for o in old.auth.User.objects.all(): > n = new.auth.User() > n.id = o.id > n.username = o.username > ... > n.save() > > # Migrate store.Book > for o in old.store.Book.objects.all(): > n = new.store.Book() > n.id = o.id > # TODO: > # Removed fields: name > # Added fields: book_name > n.save() > ... > > if __name__ == '__main__': > migrate() > > ============================= > > Then, to migrate the DB, I will edit the file, search for "TODO" > comments, and replace the comment in the file with "n.book_name = > o.name". I will create a new empty DB with the name "store_4". > > Then I will run "./migrate.py", and the database will be migrated. I > will run the new version of my site, and if everything works I can > delete the DB "store_3". > > Another thing: the migrate command will work also with only one given > site directory. In that case the old db definition and the new db > definition will be identical, and the user will be able to edit them > manually in the generated file. This feature will also help in > migrating between different types of databases - in that case, the > user will only change the settings on the top of migrate.py. > > To summarize: the programmer won't have to learn commands which add > new fields, delete fields, rename fields, modify fields, etc. The > programmer will just have to slightly modify a generated file, to > create the new version of the DB as he likes. > > I hope I managed to explain my idea. What do you think about it? > > Have a good day, > Noam > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
