多个django模型中的查询字段 [英] Query field across multiple django models

问题描述

我想创建一个最新消息部分，列出最后一天的所有数据库更改。我添加了一个更新字段到我的模型：

I want to create a "What's New" section that lists all of the database changes in the last day. I've added an "updated" field to my models:

class Film(models.Model):
   .
   .
   .
   updated = models.DateTimeField(auto_now=True)

class Actor(models.Model):
   .
   .
   .
   updated = models.DateTimeField(auto_now=True)

现在我想查询所有的模型来获取最近更改的日期排序列表。如何查询多个型号的更新字段？这是实现主要目的的最有效途径吗？

Now I want to query across all of my models to get a date-sorted list of the most recent changes. How do I query the "updated" field across multiple models? Is this the most efficient way to achieve the primary purpose?

如果我想更具体并列出每个模型中更改的实际字段怎么办？

What if I wanted to be more specific and list the actual field that was altered within each model?

推荐答案

我不知道有什么办法在多个表中运行选择...所以，除非你想在下面使用我的建议，否则你只需要遍历所有的可更新模型

I don't know of any way to run a select across multiple tables… So, unless you want to use my suggestion below, you'll just have to loop across all 'updatable' models.

但是，您可能需要考虑使用 UpdatedItems 模型，可能类似于：

However, you might want to consider having an UpdatedItems model, which might be something like:

class ItemUpdate(m.Model):
    when = m.DateTimeField(...)
    instance = m.GenericForeignKey(...)
    field = m.CharField(...)
    old_value = m.CharField(...)
    new_value = m.CharField(...)

然后使用 post_save 信号来填充它：

Then use the post_save signal to populate it:

form django.db.models.signals import post_save
def handle_post_save(sender, instance, *args, **kwargs):
    ItemUpdate(instance=instance, ...).save()

我不知道我的头顶如何弄清楚哪些字段已更新...但我确信有人在Google上询问。

I don't know off the top of my head how to figure out which fields are updated… But I'm sure someone's asked about it on Google.

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