nashvegas is a management command for managing Django database migrations
The purpose of this app is to enable a plug and play method for managing database changes.
Database migrations is a large topic with a lot of different approaches. This approach worked well for my needs and maybe it will for you as well.
How to Use
pip install nashvegas
Add the application to your INSTALLED_APPS list in your settings.py file.
Execute the command line:
$ ./manage.py upgradedb –create|–list|–execute
- --create - Compares database with current models in apps that are
- installed and outputs the sql for them so that you can easily pipe the contents to a migration.
- --list - Lists all the scripts that will need to be executed.
- --execute - Executes all the scripts that need to be executed.
Part of the simplicity of this solution is based on the naming conventions of the sql scripts. They should be named in a manner that enforces order. Some examples include:
YYYYMMDD-01.sql 0001_short_comment_about_migration.sql 0001.sql
The model, nashvegas.Migration will get synced into your database if it doesn’t exist when you go to execute any of the upgradedb commands. In this model the scripts that have been executed will be recorded, effectively versioning your database.
In addition to sql scripts, --execute will also execute python scripts that are in the directory. This are run in filename order interleaved with the sql scripts. For example:
0001.sql 0002.py 0003.sql
The Python script will be executed 2nd between 0000.sql and 0003.sql. The script will only be executed if the module contains a callable named migrate. It is a good idea to put all your executing code within a class or series of functions or within a singe migrate() function so as to avoid code executing upon import.
For example, your script might light like this if you need to update all your product codes on next release:
from store.models import Product def migrate(): for product in Product.objects.all(): product.code = "NEW-%s" % product.code product.save()