The following is a simple django custom management command to handle model field additions and deletions on a development machine. It automates a common pattern in django development – that of renaming an existing table, recreating via syncdb, and inserti

readme.markdown

Simple django management command to automate the process of renaming an existing table, recreating via syncdb, and inserting the old data into the new table. Currently does not handle field renames - will eat your data if you try.

To install, save this file into an installed django app's management/commands/ directory, eg

myapp/management/commands/simplemigration.py

Run the command from the command line as follows

python manage.py simplemigration APPNAME.MODELNAME

simplemigration.py

from django.core.management.base import BaseCommand, CommandError
from django.db import models
from django.core.management import call_command
from django.db import connection, transaction

class Command(BaseCommand):
    def handle(self, *model_labels, **options):
        for label in model_labels:
            m = models.get_model(*label.split('.'))
            temp_name = '_' + m._meta.db_table
            
            try:
                # rename table, then recreate
                cursor = connection.cursor()
                sql = 'ALTER TABLE %s RENAME TO %s' % (m._meta.db_table, temp_name)
                cursor.execute(sql)
                print sql
                call_command('syncdb')
                
                cursor = connection.cursor()
                
                old_fields = [f[0] for f in connection.introspection.get_table_description(cursor, temp_name)]
                new_fields = [f[0] for f in connection.introspection.get_table_description(cursor, m._meta.db_table)]
                
                insert_fields = [f if f in old_fields else '\'\'' for f in new_fields]
                
                # insert data from temp table into new
                sql = 'INSERT INTO %s SELECT %s FROM %s' % (m._meta.db_table, ', '.join(insert_fields), temp_name)
                cursor.execute(sql)
                print sql
                
                # drop temporary table
                sql = 'DROP TABLE %s' % (temp_name)
                cursor.execute(sql)
                print sql
            
            except Exception, e:
                print 'Last SQL statement: ' + sql
                transaction.rollback_unless_managed()
                raise
            else:
                transaction.commit_unless_managed()

See http://gregbrown.co.nz/code/django-simple-migrations/ for details