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login_user、logout_user 与会话

让用户登录和退出会话

login_user、logout_user 与会话 是 CoddyKit 上的免费 Flask Academy 课时。这是第 3 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。

Logging Someone In

Once a password checks out, you tell Flask-Login the user is signed in by calling login_user. That single call sets up the session for you.

from flask_login import login_user
login_user(user)

A Typical Login Route

In a login view you find the user, verify the password, then call login_user. After that, redirect them to a real page like the dashboard.

if user and user.check_password(pw):
    login_user(user)
    return redirect(url_for("dashboard"))

What login_user Stores

login_user does not save the whole object. It writes the user id into the session cookie, and your user_loader rebuilds the user later.

Remember Me

Pass remember=True to keep the user logged in after the browser closes. Flask-Login sets a long-lived cookie instead of a session-only one.

login_user(user, remember=True)

Accessing current_user

Anywhere in a view you can read current_user to get the logged-in person. It is a proxy that always points at the active request's user.

from flask_login import current_user
name = current_user.username

Anonymous Users

If nobody is logged in, current_user is an anonymous user object. Its is_authenticated is False, so you can branch on that safely.

if current_user.is_authenticated:
    show_dashboard()

Logging Out

To sign a user out, call logout_user. It clears their id from the session so the next request treats them as anonymous again.

from flask_login import logout_user
logout_user()

A Logout Route

A logout view is tiny: call logout_user, then redirect home. There is no password to check, only the session to clear.

@app.route("/logout")
def logout():
    logout_user()
    return redirect(url_for("index"))

Secret Key Required

Sessions ride in a signed cookie, so your app needs a SECRET_KEY. Without it, login_user raises an error and nothing works.

app.config["SECRET_KEY"] = "a-long-random-value"

Sessions Are Per-User

Each browser gets its own signed cookie, so two users never see each other's session. Flask-Login keeps them cleanly separated.

Greeting the User

In templates you can use current_user too, since Flask-Login injects it. That makes a personalized navbar a one-line job.

<p>Hello, {{ current_user.username }}</p>

Quick Check

A user clicks Log out. Which call ends their session?

Recap

You now login_user after a password check, read current_user anywhere, and call logout_user to end a session. A SECRET_KEY ties it together. 🔑

常见问题解答

「login_user、logout_user 与会话」课时是免费的吗？

是的 — 「login_user、logout_user 与会话」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。

「login_user、logout_user 与会话」这节课中我会学到什么？

让用户登录和退出会话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 3 节课，共 4 节。

「login_user、logout_user 与会话」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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