django1/django/core/management/commands/sqlmigrate.py

53 lines
2.3 KiB
Python

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from optparse import make_option
from django.core.management.base import BaseCommand, CommandError
from django.db import connections, DEFAULT_DB_ALIAS
from django.db.migrations.executor import MigrationExecutor
from django.db.migrations.loader import AmbiguityError
class Command(BaseCommand):
option_list = BaseCommand.option_list + (
make_option('--database', action='store', dest='database',
default=DEFAULT_DB_ALIAS, help='Nominates a database to create SQL for. '
'Defaults to the "default" database.'),
make_option('--backwards', action='store_true', dest='backwards',
default=False, help='Creates SQL to unapply the migration, rather than to apply it'),
)
help = "Prints the SQL statements for the named migration."
def handle(self, *args, **options):
# Get the database we're operating from
db = options.get('database')
connection = connections[db]
# Load up an executor to get all the migration data
executor = MigrationExecutor(connection)
# Resolve command-line arguments into a migration
if len(args) != 2:
raise CommandError("Wrong number of arguments (expecting 'sqlmigrate app_label migrationname')")
else:
app_label, migration_name = args
if app_label not in executor.loader.migrated_apps:
raise CommandError("App '%s' does not have migrations" % app_label)
try:
migration = executor.loader.get_migration_by_prefix(app_label, migration_name)
except AmbiguityError:
raise CommandError("More than one migration matches '%s' in app '%s'. Please be more specific." % (app_label, migration_name))
except KeyError:
raise CommandError("Cannot find a migration matching '%s' from app '%s'. Is it in INSTALLED_APPS?" % (app_label, migration_name))
targets = [(app_label, migration.name)]
# Make a plan that represents just the requested migrations and show SQL
# for it
plan = [(executor.loader.graph.nodes[targets[0]], options.get("backwards", False))]
sql_statements = executor.collect_sql(plan)
for statement in sql_statements:
self.stdout.write(statement)