59 lines
2.7 KiB
Python
59 lines
2.7 KiB
Python
# -*- coding: utf-8 -*-
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from __future__ import unicode_literals
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from django.core.management.base import BaseCommand, CommandError
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from django.db import DEFAULT_DB_ALIAS, connections
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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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help = "Prints the SQL statements for the named migration."
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output_transaction = True
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def add_arguments(self, parser):
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parser.add_argument('app_label',
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help='App label of the application containing the migration.')
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parser.add_argument('migration_name',
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help='Migration name to print the SQL for.')
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parser.add_argument('--database', default=DEFAULT_DB_ALIAS,
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help='Nominates a database to create SQL for. Defaults to the '
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'"default" database.')
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parser.add_argument('--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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def execute(self, *args, **options):
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# sqlmigrate doesn't support coloring its output but we need to force
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# no_color=True so that the BEGIN/COMMIT statements added by
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# output_transaction don't get colored either.
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options['no_color'] = True
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return super(Command, self).execute(*args, **options)
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def handle(self, *args, **options):
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# Get the database we're operating from
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connection = connections[options['database']]
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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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app_label, migration_name = options['app_label'], options['migration_name']
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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." % (
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migration_name, app_label))
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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?" % (
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migration_name, app_label))
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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['backwards'])]
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sql_statements = executor.collect_sql(plan)
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return '\n'.join(sql_statements)
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