如何使用 Python Bottle 实现文件准备就绪后自动更新的 "Your file is being prepared. Please wait 1 minute."？

Question

我想做一个 "Your file is being prepared. Please wait 1 minute." 页面，通过让客户端在文件准备就绪时下载文件来自动更新。

显然，这行不通：

from bottle import route, post, get, run, request, view, static_file, redirect
import time
from threading import Thread

def dothejob(i):
    time.sleep(10)  # the file takes 5 to 60 seconds to be prepared
    with open('test.txt', 'w') as f:
        f.write('Hello')
    return static_file('test.txt', root='.', download=True)  # error here

@get('/generatefile')
def generatefile():
    i = request.params.get('id', '', type=str)
    thread = Thread(target=dothejob, args=(i, ))
    thread.start()
    return "Your file is being prepared. Please wait 1 minute."

run(host='0.0.0.0', port=80, debug=True, quiet=True)

因为当 dothejob returns:

时 HTTP 请求不再存在

RuntimeError: Request context not initialized.

当文件在服务器上就绪时，如何正确执行这样的自动更新页面？

注：

我想在这里避免websockets（我已经将它用于更复杂的项目：聊天等，有时它在某些不接受的连接上不起作用它 + 此处不在主题的其他原因）并寻求尽可能简单的解决方案。
我想知道它是否真的需要像 Update and render a value from Flask periodically's answer 那样的 AJAX 轮询，或者是否有更简单的解决方案。

Answer 1

我试着写了一个解决方案（不是 100% 确定这样的轮询是否真的有必要）。当然 HTML+JS 必须移动到真正的 HTML / JS 文件中，但这里我为了一个最小的例子而将它保持得很小：

from bottle import get, run, request, static_file
import time
from threading import Thread
import os

def dothejob(i):
    time.sleep(5)  # the file takes 5 to 60 seconds to be prepared
    with open('test.txt', 'w') as f:
        f.write('Hello')

@get('/<filename>')
def static(filename):
    return static_file(filename, root='.', download=True)

@get('/isready')
def isready():
    return '1' if os.path.exists('test.txt') else '0'

@get('/')
def generatefile():
    i = request.params.get('id', '', type=str)
    thread = Thread(target=dothejob, args=(i, ))
    thread.start()
    return """Your file is being prepared. Please wait 5 seconds (do not reload the page)...
<script>
poll = function () {
    var xhr = new XMLHttpRequest();
    xhr.open('GET', '/isready');
    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            if (xhr.responseText == 1)
                document.write('Your file is now ready: <a href="/test.txt">download link</a>');
            else
                setTimeout(poll, 1000);
        }
    }
    xhr.send(null);
}

setTimeout(poll, 1000);
</script>
"""    

run(host='0.0.0.0', port=80, debug=True, quiet=True)

如何使用 Python Bottle 实现文件准备就绪后自动更新的 "Your file is being prepared. Please wait 1 minute."？

How to implement "Your file is being prepared. Please wait 1 minute." that auto-updates when the file is ready with Python Bottle?

python

multithreading

asynchronous

bottle