dependencies = [('myapp', 'previous_migration')]
operations = []

def apply(self, project_state, schema_editor, collect_sql=False):
    cursor = connection.cursor()
cursor.execute(
    'alter table myapp_host alter column created_at set default current_timestamp'
    )
return super(Migration, self).apply(project_state, schema_editor, collect_sql)
How to set default column value in the db using django 1.7.3/postgres migrations?