Django自定义主键 [英] Django Custom primary key

问题描述

当我检查Trac数据库时，我得到:

When I inspect the Trac database I get:

class TicketChange(models.Model):
    ticket = models.IntegerField()
    time = models.BigIntegerField()
    author = models.TextField(blank=True)
    field = models.TextField()
    oldvalue = models.TextField(blank=True)
    newvalue = models.TextField(blank=True)
    class Meta:
        managed = False
        db_table = 'ticket_change'

没有主键:

>>> TicketChange.objects.all()
DatabaseError: column ticket_change.id does not exist
LINE 1: SELECT "ticket_change"."id", "ticket_change"."ticket", "tick...

因为我需要指定一个pk，但是Trac中 ticket_change 的原始主键是:

Because I need to specify a pk but the original primary key of ticket_change in Trac is:

Primary key (ticket, time, field)

但是在Django中是不可能的: Django多列主键讨论.

But It's not possible in Django: Django Multi-Column Primary Key Discussion.

如果我像pk那样定义 time ，则无法同时添加两个票证更改.

If I define time like pk I can't add two tickets changes in the same time.

我该怎么办?

推荐答案

您是对的.这是一个已知的问题.因此，唯一的解决方案是骇客(之类).

You're right. It's a known problem. So the only solutions are hacks (sort of).

您最好的选择是使用 django-compositepks .缺点是它实际上并不支持模型关系，因此您将无法从Composite-pk模型导航到任何关系.但是，查看您的TicketChange模型似乎不是问题(除非您有更多与此模型相关的模型).

Your best option is to use django-compositepks. The drawbacks are that it doesn't really support model relationships, so you will not be able to navigate to any relationship from your composite-pk model. However, looking at your TicketChange model this doesn't seem like an issue (unless you have more models with relationships to this one).

另一种选择是手动添加id列(并确保对数据库应用所有其他更改)，从而创建新的单列主键.第三种选择(以及我可能会做的)与最后一种选择非常相似，但是更简洁，它是从头开始创建一个新数据库，然后通过从现有旧数据库中获取数据来用脚本填充该数据库.

Another option would be to manually add the id column (and make sure to apply any additional changes to the db), thereby creating the new one-column primary key. A third option (and what I would probably do), pretty similar to the last one but cleaner, would be to create a new database from scratch and then populate it with a script by fetching the data from your existing legacy db.

对不起，我没有适合您的更好的解决方案，事实就是这样.旧版dbs和django总是让人头疼，我自己也经历了一些类似的过程.希望这会有所帮助！

Sorry I don't have any better solution for you, that's the way it is. Legacy dbs and django are always a headache, have gone through some similar processes myself. Hope this helps!

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