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copied!<h2>How to migrate using south.</h2> <p>Lets say we got two apps: common and specific:</p> <pre class="lang-none prettyprint-override"><code>myproject/ |-- common | |-- migrations | | |-- 0001_initial.py | | `-- 0002_create_cat.py | `-- models.py `-- specific |-- migrations | |-- 0001_initial.py | `-- 0002_create_dog.py `-- models.py </code></pre> <p>Now we want to move model common.models.cat to specific app (precisely to specific.models.cat). First make the changes in the source code and then run:</p> <pre class="lang-none prettyprint-override"><code>$ python manage.py schemamigration specific create_cat --auto + Added model 'specific.cat' $ python manage.py schemamigration common drop_cat --auto - Deleted model 'common.cat' myproject/ |-- common | |-- migrations | | |-- 0001_initial.py | | |-- 0002_create_cat.py | | `-- 0003_drop_cat.py | `-- models.py `-- specific |-- migrations | |-- 0001_initial.py | |-- 0002_create_dog.py | `-- 0003_create_cat.py `-- models.py </code></pre> <p>Now we need to edit both migration files:</p> <pre class="lang-py prettyprint-override"><code>#0003_create_cat: replace existing forward and backward code #to use just one sentence: def forwards(self, orm): db.rename_table('common_cat', 'specific_cat') if not db.dry_run: # For permissions to work properly after migrating orm['contenttypes.contenttype'].objects.filter( app_label='common', model='cat', ).update(app_label='specific') def backwards(self, orm): db.rename_table('specific_cat', 'common_cat') if not db.dry_run: # For permissions to work properly after migrating orm['contenttypes.contenttype'].objects.filter( app_label='specific', model='cat', ).update(app_label='common') </code></pre> <hr> <pre class="lang-py prettyprint-override"><code>#0003_drop_cat:replace existing forward and backward code #to use just one sentence; add dependency: depends_on = ( ('specific', '0003_create_cat'), ) def forwards(self, orm): pass def backwards(self, orm): pass </code></pre> <p>Now both apps migrations are aware of the change and life sucks just a little less :-) Setting this relationship between migrations is key of success. Now if you do:</p> <pre class="lang-none prettyprint-override"><code>python manage.py migrate common > specific: 0003_create_cat > common: 0003_drop_cat </code></pre> <p>will do both migration, and </p> <pre class="lang-none prettyprint-override"><code>python manage.py migrate specific 0002_create_dog < common: 0003_drop_cat < specific: 0003_create_cat </code></pre> <p>will migrate things down.</p> <p><strong>Notice that for upgrading of schema I used common app and for downgrading, I used specific app. That's because how the dependency here works.</strong></p>

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