简单初中计算题：$x/2=8/x$，$x$=？
求下图中$x$的值。
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Django change an existing field to foreign key
I have a Django model that used to look like this:class Car(models.Model): manufacturer_id = models.IntegerField()There is another model called Manufacturer that the id field refers to. However, I realized that it would be useful to use Django's built-in foreign key functionality, so I changed the model to this:class Car(models.Model): manufacturer = models.ForeignKey(Manufacturer)This change appears to work fine immediately, queries work without errors, but when I try to run migrations, Django outputs the following:- Remove field manufacturer_id from car - Add field manufacturer to carDoing this migration would clear all the existing relationships in the database, so I don't want to do that. I don't really want any migrations at all, since queries like Car.objects.get(manufacturer__name="Toyota") work fine. I would like a proper database foreign key constraint, but it's not a high priority.So my question is this: Is there a way to make a migration or something else that allows me to convert an existing field to a foreign key? I cannot use --fake since I need to reliably work across dev, prod, and my coworkers' computers.内容来源于 Stack Overflow, 遵循 CCBY-SA 4.0 许可协议进行翻译与使用。原文链接：Django change an existing field to foreign key
[antd: Message] You are calling notice in render which will break in React 18 concurrent mode. Please trigger in effect instead.
I'm getting this error when using MessageWarning: [antd: Message] You are calling notice in render which will break in React 18 concurrent mode. Please trigger in effect instead.Here is my code:import { message } from 'antd'; export default function Page() { const [messageApi, contextHolder] = message.useMessage(); const res = await fetch("/api/...", { method: "POST", }); if (!res.ok) { messageApi.error("Error! Fail to login!"); } return ( <Home> ... </Home> ) }