Question

我有一个简单的迁移，如下所示：

class Migration(SchemaMigration):

    def forwards(self, orm):
        db.add_column('activities_newsitem', 'related_story', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['projects.Story'], null=True, blank=True),keep_default=True)

不幸的是，它失败了，我不知道为什么。以下是输出。请注意，它运行添加列查询就好了。事实上，当我查看数据库时，列就是正确的。

但出于某种原因，它之后会运行一个drop column，那就是失败了。为什么这样做？

DEBUG south execute "ALTER TABLE `activities_newsitem` ADD COLUMN `related_story_id` integer NULL;" with params "[]" (generic.py:145)
DEBUG south execute "ALTER TABLE `activities_newsitem` ADD CONSTRAINT `related_story_id_refs_id_3d3841088db0fdb0` FOREIGN KEY (`related_story_id`) REFERENCES `projects_story` (`id`);" with params "[]" (generic.py:145)
DEBUG south execute "CREATE INDEX `activities_newsitem_related_story_id` ON `activities_newsitem` (`related_story_id`);" with params "[]" (generic.py:145)
DEBUG south execute "ALTER TABLE `activities_newsitem` ADD COLUMN `related_story_id` integer NULL;" with params "[]" (generic.py:145)
DEBUG south execute "ALTER TABLE `activities_newsitem` ADD CONSTRAINT `related_story_id_refs_id_3d3841088db0fdb0` FOREIGN KEY (`related_story_id`) REFERENCES `projects_story` (`id`);" with params "[]" (generic.py:145)
DEBUG south execute "ALTER TABLE `activities_newsitem` DROP COLUMN `related_story_id` CASCADE;" with params "[]" (generic.py:145)
 ! Error found during real run of migration! Aborting.

 ! Since you have a database that does not support running
 ! schema-altering statements in transactions, we have had 
 ! to leave it in an interim state between migrations.

感谢您的帮助

Answer 1

看起来它试图两次运行你的命令。如果查看迁移文件夹，是否有2个相同的迁移？如果您在没有实际迁移的情况下运行两次create migration命令，则可能会执行此操作。

你是不是意外地执行了两次命令？您可以通过打开数据库控制台并检查迁移是否在south_migrationhistory表中来检查这一点。

假设您使用的是unixy系统（OSX / Linux），请从命令行：

mysql -u username -p password

然后

select * from south_migrationhistory;

您的迁移是否在那里？

如果是这样，您的任务就完成了，您可以继续前进。如果不是，且您的activities_newsitem表中包含该列，则需要伪造迁移以使您的南迁移历史记录保持最新状态。

虚假迁移：

python manage.py migrate activities --fake 0001

其中0001是迁移号码（所有迁移文件都以数字为前缀）。

为什么South试图删除我想要添加的列？

1 个答案: