Flask表单request.form.get('url')返回None问题求助

使用Flask+HTML开发YouTube下载工具，提交表单后request.form.get('url')返回None，无法获取输入的视频URL。以下是相关代码，怀疑问题出在HTML表单中。

HTML代码 #

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>YouTube Download</title>
    <link rel="stylesheet" href="../static/css/style.css">
    <link href="{{ url_for('static', filename='css/style.css') }}" rel="stylesheet">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
</head>

<body>
    <div class="banner">
        <h1 class="title" data-text="Youtube Download"><i class="fa fa-music"></i> Youtube Download</h1>
        <form action="{{ url_for('downloadMP3') }}" method="POST">
            <p>Ingresa la URL del Video
            </p>
            <br>
            <input class="form-control" type="text" id="url" name=“url” >
            <div class="btn-group">
                <button class="btn" type="submit" formaction="/downloadMP4">
                    <i class="fa fa-download"> </i> Download MP4
                </button>
                <button class="btn" type="submit" formaction="/downloadMP3">
                    <i class="fa fa-download"> </i> Download MP3
                </button>
            </div>
        </form>
    </div>
</body>

</html>

Python代码 #

from flask import Flask, render_template, request, Response, redirect, send_file
import os
from os import remove
import pafy
import moviepy.editor as mp

app = Flask(__name__)
path=os.getcwd() + '/'

@app.route('/')
def route():
    return render_template('index.html')

@app.route('/downloadMP4', methods=['GET', 'POST'])
def downloadMP4():
    if request.method == 'POST':
        url = request.form.get("url")
        video = pafy.new(url)
        best = video.getbest(preftype="mp4")
        best.download(path)
        p = path + video.title + '.mp4'

    return send_file(p, as_attachment=True)

@app.route('/downloadMP3', methods=['GET', 'POST'])
def downloadMP3():
    if request.method == 'POST':
        url = request.form.get("url")
        video = pafy.new(url)
        best = video.getbest(preftype="mp4")
        best.download(path)
        name = path + video.title + '.mp4'
        clip = mp.VideoClip(name)
        clip.audio.write_audiofile(path + video.title + '.mp3')
        p = path + video.title + '.mp3'

    return send_file(p, as_attachment=True)

if __name__ == '__main__':
    app.run(host='localhost', port=5000)

解决方案 #

核心问题：HTML表单的引号错误 #

HTML中input标签的name属性使用了中文双引号（“url”），而非标准的英文双引号（"url"），导致Flask无法识别表单字段，返回None。

修正后的input标签：

<input class="form-control" type="text" id="url" name="url" >

额外优化建议 #

1. 移除重复的静态资源引用：HTML头部重复引入了style.css，保留Flask的url_for方式即可，避免路径问题：

<link href="{{ url_for('static', filename='css/style.css') }}" rel="stylesheet">

2. 处理异常情况：Python代码中未对url为空、视频下载失败等情况做处理，容易报错，可添加判断：

@app.route('/downloadMP4', methods=['GET', 'POST'])
def downloadMP4():
    if request.method == 'POST':
        url = request.form.get("url")
        if not url:
            return "请输入有效的YouTube URL", 400
        try:
            video = pafy.new(url)
            best = video.getbest(preftype="mp4")
            best.download(path)
            p = path + video.title + '.mp4'
            return send_file(p, as_attachment=True)
        except Exception as e:
            return f"下载失败：{str(e)}", 500
    return redirect('/')

3. 清理临时文件：下载完成后可删除临时的MP4文件（尤其是转MP3的场景），避免占用磁盘空间：

# 在MP3下载的函数中，转码完成后删除原MP4文件
os.remove(name)

内容的提问来源于stack exchange，提问作者Ezequiel Bonasegla