Assign the value of old column to new column using Django data migration -

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i got problem when wanted change column's type int char. could't directly via django migrations. firstly added new column , wanted set value old column's, sql 'update my_app_myqpp set uuid=id'. how can via django migrations? thanks!

def migrate_data(apps, schema_editor):     myapp = apps.get_model('my_app', 'myapp')     db_alias = schema_editor.connection.alias     results = myapp.objects.using(db_alias)     result in results:         result.uuid = str(result.id)         result.save()   class migration(migrations.migration):      dependencies = [         ('myq_app', '0002_auto_20150205_0501'),     ]      operations = [         migrations.addfield(             model_name='myapp',             name='uuid',             field=api.fields.uuidfield(auto_created=true, default='0', editable=false, max_length=32, unique=true, verbose_name='uuid'),             preserve_default=true,         ),          migrations.runpython(migrate_data)     ]

i tried

myapp.objects.raw('update docker_build_dockerbuild set uuid=id')

but seemed migrate_data not performed.

finally got problem solved. way simple. separated migrations 2 steps, 1 add new field , other 1 migrate data. reason '0002_auto_20150205_0501' didn't include new field. 'result.save' didn't update non-exist column 'uuid' result.uuid set value


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