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Automatically migrate SQL schema in SQLObject
Sun, 02 Nov 2008 18:58:35 +0000
When you're building an application you have to extends your model (and alter database schema that is placed under the model). I've found a method to automatically upgrade SQL schema (only ADD COLUMN operations for now):
from sqlobject import *
import logging

class Base(SQLObject):

    def migrate(self, *args, **kv):

        conn = self._connection
        schema = {}
        cols = self.sqlmeta.columns

        for a in conn.columnsFromSchema(self.sqlmeta.table, self):
            schema[a.name] = a
        logging.debug("existing schema: %s" % schema)

        for name, col in cols.iteritems():
            if name not in schema.keys():
                logging.info("add column: %s.%s" % (self.__class__.__name__, name))

    migrate = classmethod(migrate)
migrate() class method only handles simplest case (adding a new column), but it may be sufficient in typical development process (more advanced transformations will still require SQL migration scripts written by hand). Enjoy!

Tags: python, sql.


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