Synnefo

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from sqlalchemy import Table, Column, String, MetaData

from sqlalchemy.sql import select

from sqlalchemy.exc import NoSuchTableError

from dbworker import DBWorker

def create_tables(engine):

    metadata = MetaData()

    columns = []

    columns.append(Column('key', String(256), primary_key=True))

    columns.append(Column('value', String(256)))

    config = Table('config', metadata, *columns, mysql_engine='InnoDB')

    metadata.create_all(engine)

    return metadata.sorted_tables

class Config(DBWorker):

    """Config are properties holding persistent information about system state.

    """

    def __init__(self, **params):

        DBWorker.__init__(self, **params)

        try:

            metadata = MetaData(self.engine)

            self.config = Table('config', metadata, autoload=True)

        except NoSuchTableError:

            tables = create_tables(self.engine)

            map(lambda t: self.__setattr__(t.name, t), tables)

    def get_value(self, key):

        """Return configuration value for key."""

        s = select([self.config.c.value])

        s = s.where(self.config.c.key == key)

        r = self.conn.execute(s)

        row = r.fetchone()

        r.close()

        if row:

            return row[0]

        return None

    def set_value(self, key, value):

        """Set a configuration entry.

        """

        s = self.config.insert()

        r = self.conn.execute(s, key=key, value=value)

        inserted_primary_key = r.inserted_primary_key[0]

        r.close()

        return inserted_primary_key