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类型转换器：int、float、string、path

使用内置转换器限制 URL 片段

类型转换器：int、float、string、path 是 CoddyKit 上的免费 Flask Academy 课时。这是第 2 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。

Strings Are Not Always Enough

Captured values default to strings, but /post/42 should give a number, not text. A converter tells Flask what type to expect in that segment.

Converter Syntax

Put the converter name before the variable with a colon. The pattern is <converter:name>, and Flask applies it before calling your view.

@app.route('/post/<int:post_id>')
def show(post_id):
    return str(post_id + 1)

The int Converter

Use int to capture whole numbers. /post/42 hands your view the integer 42, so you can do math without calling int() yourself. 🔢

@app.route('/page/<int:n>')
def page(n):
    return f'Page {n}'

int Rejects Non-Numbers

A converter also filters URLs. /page/abc will not match an int route, so Flask returns 404 instead of crashing inside your function.

The float Converter

Use float for decimal numbers like prices or ratings. /rate/4.5 gives you the float 4.5, ready for arithmetic right away.

@app.route('/rate/<float:score>')
def rate(score):
    return str(score * 2)

The string Converter

string is the default: it accepts any text but stops at a slash. You rarely write it explicitly since plain <name> already behaves this way.

@app.route('/tag/<string:label>')
def tag(label):
    return label

The path Converter

Use path when the value can contain slashes, like a folder route. Unlike string, it captures /docs/intro/setup as one whole value.

@app.route('/files/<path:filepath>')
def serve(filepath):
    return filepath

Pick the Right Tool

Match the converter to your data: int for ids, float for decimals, string for words, path for slashed routes. The right choice prevents bad input early.

Converters Validate for You

By rejecting mismatched URLs with a 404, converters act as a first line of validation. Your view only runs when the type already fits.

Combine in One Route

You can mix converters across segments. Here an int id and a string tab live in the same path, each typed independently.

@app.route('/user/<int:uid>/<tab>')
def view(uid, tab):
    return f'{uid}:{tab}'

Negatives and Edge Cases

The built-in int converter matches only non-negative whole numbers by default. For minus signs or stricter rules, you would write a custom converter later.

Quick Check

Which converter lets a captured value include slashes, like docs/intro/setup?

Recap: You Typed Your URLs

Converters give captured values a type and reject bad input with a 404. Remember int, float, string, and path. Next: building URLs safely. 🧭

常见问题解答

「类型转换器：int、float、string、path」课时是免费的吗？

是的 — 「类型转换器：int、float、string、path」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。

「类型转换器：int、float、string、path」这节课中我会学到什么？

使用内置转换器限制 URL 片段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 2 节课，共 4 节。

「类型转换器：int、float、string、path」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。

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