I would like to change a name of specific fields in a model:
class Foo(models.Model): name = models.CharField() rel = models.ForeignKey(Bar)
should change to:
class Foo(models.Model): full_name = models.CharField() odd_relation = models.ForeignKey(Bar)
What's the easiest way to do this using South?
You can use the
class Migration: def forwards(self, orm): # Rename 'name' field to 'full_name' db.rename_column('app_foo', 'name', 'full_name') def backwards(self, orm): # Rename 'full_name' field to 'name' db.rename_column('app_foo', 'full_name', 'name')
The first argument of
db.rename_column is the table name, so it's important to remember how Django creates table names:
Django automatically derives the name of the database table from the name of your model class and the app that contains it. A model's database table name is constructed by joining the model's "app label" -- the name you used in manage.py startapp -- to the model's class name, with an underscore between them.
In the case where you have a multi-worded, camel-cased model name, such as ProjectItem, the table name will be
app_projectitem (i.e., an underscore will not be inserted between
item even though they are camel-cased).
Here's what I do:
./manage.py schemamigration myapp renaming_column_x --auto
renaming_column_x can be anything you like, it's just a way of giving a descriptive name to the migration file.
This will generate you a file called
myapp/migrations/000x_renaming_column_x.py which will delete your old column and add a new column.
Modify the code in this file to change the migration behaviour to a simple rename:
class Migration(SchemaMigration): def forwards(self, orm): # Renaming column 'mymodel.old_column_name' to 'mymodel.new_column_name' db.rename_column(u'myapp_mymodel', 'old_column_name', 'new_column_name') def backwards(self, orm): # Renaming column 'mymodel.new_column_name' to 'mymodel.old_column_name' db.rename_column(u'myapp_mymodel', 'new_column_name', 'old_column_name')