from optparse import make_option

from django.core.management.base import BaseCommand, CommandError

from django.db import connections, DEFAULT_DB_ALIAS

class Command(BaseCommand):

    help = ("Runs the command-line client for specified database, or the "

        "default database if none is provided.")

    option_list = BaseCommand.option_list + (

        make_option('--database', action='store', dest='database',

            default=DEFAULT_DB_ALIAS, help='Nominates a database onto which to '

                'open a shell.  Defaults to the "default" database.'),

    )

    requires_model_validation = False

    def handle(self, **options):

        connection = connections[options.get('database', DEFAULT_DB_ALIAS)]

        try:

            connection.client.runshell()

        except OSError:

            # Note that we're assuming OSError means that the client program

            # isn't installed. There's a possibility OSError would be raised

            # for some other reason, in which case this error message would be

            # inaccurate. Still, this message catches the common case.

            raise CommandError('You appear not to have the %r program installed or on your path.' % \

                connection.client.executable_name)