将my.packages重命名为my.package [英] Renaming my.packages to my.package

问题描述

my.packages是src目录中的自定义原型程序包. Plone实例中的数千个项目及其类型被添加.我想将包重命名为my.package.通过简单地卸载my.packages并安装my.package，我发现 http://localhost:8080/mysite /myfolder/my-item 显示<persistent broken my.packages.content.mytype.MyType instance '\x00\x00\x00\x00\x00Un^'>.我应该做迁移吗?还是有解决此问题的简单方法?

my.packages is a custom archetypes package in the src directory. Thousands of items in the Plone instance are added with its types. I want to rename the package as my.package. By simply uninstalling my.packages and installing my.package, I find http://localhost:8080/mysite/myfolder/my-item showing <persistent broken my.packages.content.mytype.MyType instance '\x00\x00\x00\x00\x00Un^'>. Should I have to do migration? Or is there a simple way to fix this issue?

推荐答案

通过使用sys.modules进行混淆，可以创建一个向后兼容的别名.在您的软件包__init__.py:

You can create an alias for backward compatibility, by fudzing with sys.modules. Do this in your package __init__.py:

 import sys
 sys.modules['my.packages'] = sys.modules[__name__]

通过这种方式，持久性机制仍可以找到您的类.

This way the persistence machinery can find your classes still.

发生的事情是，当您的原型实例保留在ZODB中时，持久性机制将类的模块路径(点划线的python路径，例如my.packages.types.foobar.FooBar)存储在存储的数据中.从ZODB恢复对象时，该路径将用于重新创建实例.重命名程序包时，所有这些引用都被破坏了.

What happens is that when your Archetypes instances are persisted in the ZODB, the persistence machinery stores a module path for the class (a dotted python path such as my.packages.types.foobar.FooBar) in the stored data. When restoring an object from the ZODB, that same path is then used to re-create your instances. When you rename your package, all these references are broken.

使用上述技巧，很好的是，如果在事务中更改了对象并将其再次写入ZODB，将存储 new 模块路径.因此，可以想象导致对该程序包中的所有Archetypes实例进行写操作，以使迁移永久进行，因此您可以再次删除上述变通方法.

With the above trick, the nice thing is that if your object were changed and written to the ZODB again in a transaction, the new module path will be stored. You could thus conceivable cause a write to all your Archetypes instances from this package to make the migration permanent so you can remove the above work-around again.

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