Tkinter YouTube下载按钮无法识别链接，报RegexMatchError如何解决？

我是编程新手，首次使用Tkinter开发YouTube下载器。点击Download按钮后代码无法下载视频，触发RegexMatchError，推测问题出在yt = YouTube(f"{url}")这行，恳请协助解决。

原代码 #

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showinfo
from pytube import YouTube

root = tk.Tk()
root.geometry("400x200")
root.resizable(False, False)
root.title("Youtube Downloader")

tk.Label(root, text="Hello :)\nWelcome to Youtube Downloader.\n").pack()

url = tk.StringVar()

# Link frame
link = ttk.Frame(root)
link.pack(padx=10, pady=10, fill='x', expand=True)

# Link
link_label = ttk.Label(link, text="Enter the Youtube link:\n")
link_label.pack(fill='x', expand=True)

link_entry = ttk.Entry(link, textvariable=url)
link_entry.pack(fill='x', expand=True)
link_entry.focus()


# download button
def download_clicked():
    print("Welcome to Youtube Downloader.")
    showinfo(
        title='Information',
        message='Download has began!'
    )
    yt = YouTube(f"{url}")
    stream = yt.streams.get_by_itag(22)
    size = round(stream.filesize / 10 ** 6, 2)

    print(f"Downloading {yt.title}, \n Length: {yt.length} seconds, \n Size: {size} MBs")


download_button = ttk.Button(
    root,
    text='Download',
    compound=tk.LEFT,
    command=download_clicked
)

download_button.pack(ipadx=5, ipady=5, expand=True)

# Exit button
exit_button = ttk.Button(
    root,
    text='Exit',
    command=lambda: root.quit()
)

exit_button.pack(
    ipadx=5,
    ipady=5,
    expand=True,
    side="left"
)

try:
    from ctypes import windll

    windll.shcore.SetProcessDpiAwareness(1)
finally:
    root.mainloop()

报错信息 #

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\hp\AppData\Local\Programs\Python\Python310\lib\tkinter\__init__.py", line 1921, in __call__
    return self.func(*args)
  File "c:\Users\hp\Desktop\git\YoutubeDownloader\tkinter yt dowloader.py", line 36, in download_clicked
    yt = YouTube(f"{url}")
  File "C:\Users\hp\AppData\Local\Programs\Python\Python310\lib\site-packages\pytube\__main__.py", line 71, in __init__
    self.video_id = extract.video_id(url)
  File "C:\Users\hp\AppData\Local\Programs\Python\Python310\lib\site-packages\pytube\extract.py", line 133, in video_id
    return regex_search(r"(?:v=|\/)([0-9A-Za-z_-]{11}).*", url, group=1)
  File "C:\Users\hp\AppData\Local\Programs\Python\Python310\lib\site-packages\pytube\helpers.py", line 129, in regex_search
    raise RegexMatchError(caller="regex_search", pattern=pattern)        
pytube.exceptions.RegexMatchError: regex_search: could not find match for (?:v=|\/)([0-9A-Za-z_-]{11}).*

问题原因与修复方案 #

1. 核心问题：url是Tkinter的StringVar对象，直接用f"{url}"转换字符串时，得到的是对象描述文本（类似PY_VAR0），而非用户输入的YouTube链接，导致pytube无法解析视频ID，触发RegexMatchError。

2. 修复步骤：

   • 将yt = YouTube(f"{url}")修改为yt = YouTube(url.get())，调用get()方法获取StringVar中存储的实际链接文本。
   • 原代码仅获取了视频流信息，未执行下载操作，需添加stream.download()启动下载。
   • 可选：添加输入校验，防止空链接或无效链接，避免不必要的报错。

修改后的完整代码 #

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showinfo, showerror
from pytube import YouTube

root = tk.Tk()
root.geometry("400x200")
root.resizable(False, False)
root.title("Youtube Downloader")

tk.Label(root, text="Hello :)\nWelcome to Youtube Downloader.\n").pack()

url = tk.StringVar()

# Link frame
link = ttk.Frame(root)
link.pack(padx=10, pady=10, fill='x', expand=True)

# Link
link_label = ttk.Label(link, text="Enter the Youtube link:\n")
link_label.pack(fill='x', expand=True)

link_entry = ttk.Entry(link, textvariable=url)
link_entry.pack(fill='x', expand=True)
link_entry.focus()


# download button
def download_clicked():
    print("Welcome to Youtube Downloader.")
    video_url = url.get().strip()
    if not video_url:
        showerror(title="Error", message="请输入YouTube链接")
        return
    
    try:
        showinfo(title='Information', message='下载已开始!')
        yt = YouTube(video_url)
        stream = yt.streams.get_by_itag(22)  # 720p MP4格式
        if not stream:
            showerror(title="Error", message="无法找到指定格式的视频流")
            return
        
        size = round(stream.filesize / 10 ** 6, 2)
        print(f"正在下载 {yt.title}, \n 时长: {yt.length} 秒, \n 大小: {size} MB")
        
        # 执行下载，默认保存到当前目录
        stream.download()
        showinfo(title="Success", message="下载完成!")
    except Exception as e:
        showerror(title="Error", message=f"下载失败: {str(e)}")
        print(f"错误信息: {str(e)}")


download_button = ttk.Button(
    root,
    text='Download',
    compound=tk.LEFT,
    command=download_clicked
)

download_button.pack(ipadx=5, ipady=5, expand=True)

# Exit button
exit_button = ttk.Button(
    root,
    text='Exit',
    command=lambda: root.quit()
)

exit_button.pack(
    ipadx=5,
    ipady=5,
    expand=True,
    side="left"
)

try:
    from ctypes import windll
    windll.shcore.SetProcessDpiAwareness(1)
finally:
    root.mainloop()

内容的提问来源于stack exchange，提问作者Gray Black