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请求之间的 Flash 消息

在重定向后显示一次性提示

请求之间的 Flash 消息 是 CoddyKit 上的免费 Flask Academy 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Flask Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Flask Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

The One-Time Notice

After saving a form you often want to show Saved! once, then never again. Flask calls this a flash message. ✨

Why Not Just Pass It

The trick is that you usually redirect after a save, and the redirect loses your variables. Flash survives that hop for you.

It Rides the Session

Under the hood, flash tucks the message into the session, so you must have a SECRET_KEY configured for it to work.

Flash a Message

In your view, call flash with the text right before you redirect the user to the next page.

from flask import flash, redirect
flash('Profile saved!')
return redirect('/profile')

Read Them in the Template

On the destination page you pull the queued notices with get_flashed_messages and loop over them in Jinja2.

{% for m in get_flashed_messages() %}
  <p>{{ m }}</p>
{% endfor %}

Shown Once Only

Reading the messages also clears them. Refresh the page and the notice is gone, exactly the behavior you want.

Add a Category

Pass a second argument to tag a message with a category like success or error, so you can style each kind differently.

flash('Wrong password', 'error')

Read Categories Too

Ask for categories with with_categories set to true, and each entry becomes a category and message pair.

{% for cat, m in get_flashed_messages(with_categories=true) %}

Filter by Category

You can also request only certain kinds using category_filter, handy when one block shows just errors.

get_flashed_messages(category_filter=['error'])

Put It in the Layout

Render flashes in your base template so every page can surface notices without repeating the loop everywhere.

Keep Them Short

Flash is for brief, friendly feedback, not long reports. One clear sentence per message keeps the experience clean.

Quick Check

Consider what happens after a template reads the flashed messages.

Recap

You learned that flash queues a one-time message through the session, survives a redirect, and clears once shown. 🎉

常见问题解答

「请求之间的 Flash 消息」课时是免费的吗？

是的 — 「请求之间的 Flash 消息」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Flask Academy 课程的其余内容，请升级到 CoddyKit PRO。 Flask Academy 课程共包含 4 节课。

「请求之间的 Flash 消息」这节课中我会学到什么？

在重定向后显示一次性提示你通过在浏览器中直接运行的动手代码来练习 Flask Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Flask Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Flask Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「请求之间的 Flash 消息」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Flask Academy 课中编写并运行代码吗？

能。每节 Flask Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

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