53 lines
2.3 KiB
Python
53 lines
2.3 KiB
Python
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# encoding: utf8
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from __future__ import unicode_literals
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from optparse import make_option
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from django.core.management.base import BaseCommand, CommandError
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from django.db import connections, DEFAULT_DB_ALIAS
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from django.db.migrations.executor import MigrationExecutor
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from django.db.migrations.loader import AmbiguityError
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class Command(BaseCommand):
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option_list = BaseCommand.option_list + (
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make_option('--database', action='store', dest='database',
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default=DEFAULT_DB_ALIAS, help='Nominates a database to create SQL for. '
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'Defaults to the "default" database.'),
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make_option('--backwards', action='store_true', dest='backwards',
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default=False, help='Creates SQL to unapply the migration, rather than to apply it'),
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)
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help = "Prints the SQL statements for the named migration."
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def handle(self, *args, **options):
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# Get the database we're operating from
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db = options.get('database')
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connection = connections[db]
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# Load up an executor to get all the migration data
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executor = MigrationExecutor(connection)
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# Resolve command-line arguments into a migration
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if len(args) != 2:
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raise CommandError("Wrong number of arguments (expecting 'sqlmigrate appname migrationname')")
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else:
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app_label, migration_name = args
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if app_label not in executor.loader.migrated_apps:
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raise CommandError("App '%s' does not have migrations" % app_label)
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try:
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migration = executor.loader.get_migration_by_prefix(app_label, migration_name)
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except AmbiguityError:
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raise CommandError("More than one migration matches '%s' in app '%s'. Please be more specific." % (app_label, migration_name))
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except KeyError:
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raise CommandError("Cannot find a migration matching '%s' from app '%s'. Is it in INSTALLED_APPS?" % (app_label, migration_name))
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targets = [(app_label, migration.name)]
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# Make a plan that represents just the requested migrations and show SQL
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# for it
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plan = [(executor.loader.graph.nodes[targets[0]], options.get("backwards", False))]
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sql_statements = executor.collect_sql(plan)
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for statement in sql_statements:
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self.stdout.write(statement)
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