线程完成后，如何在Flask中更改渲染的模板? [英] How do I change the rendered template in Flask when a thread completes?
问题描述
我有一个功能，可以在网上抓取数据并计算搜索得分.但是，这可能需要一段时间，有时网页会在完成执行之前超时.
I have a function that crawls the web for data and computes a score for the search. However, this can take a while and sometimes the webpage times out before finishing execution.
因此，我创建了一个单独的线程来执行该函数，并创建 loading.html 来告诉客户端仍在收集数据.函数在线程中结束后，如何重新加载网页以显示显示分数的 output.html .
So I created a separate thread that executes the function and loading.html that tells the client that data is still being collected. Once the function ends in the thread, how do I reload the webpage to display output.html that displays the score.
这是我到目前为止的简单版本:
This is a simpler version of what I have so far:
from flask import Flask
from flask import render_template
from threading import Thread
app = Flask(__name__)
@app.route("/")
def init():
return render_template('index.html')
@app.route("/", methods=['POST'])
def load():
th = Thread(target=something, args=())
th.start()
return render_template('loading.html')
def something():
#do some calculation and return the needed value
if __name__ == "__main__":
app.run()
如何将我的应用程序路由到第 th something()一旦，将我的应用路由到 render_template('output.html'，x = score)>完成?
How do I route my app to render_template('output.html', x=score) once something() inside the thread th finishes?
我想避免像redis这样的任务队列，因为我想在Web上部署此应用程序，并且我不想产生任何费用(这更多是实验和业余爱好).
I am trying to avoid task queues like redis since I want to deploy this app on the web and I don't want to incur charges (this is more of an experiment and hobby).
代码的详细答案对我很有帮助，因为我是flask和multithreading的新手.
A detailed answer with code would help a lot since I am new to flask and multithreading
推荐答案
一种简单的方法是向 thread_status 端点发出循环Ajax请求，从而向您提供有关当前正在运行的任务的信息.
An easy way is making cyclic Ajax requests to a thread_status endpoint that gives you information about the currently running task.
import time
from flask import Flask, jsonify
from flask import render_template
from threading import Thread
app = Flask(__name__)
th = Thread()
finished = False
@app.route("/")
def init():
return render_template('index.html')
@app.route("/", methods=['POST'])
def load():
global th
global finished
finished = False
th = Thread(target=something, args=())
th.start()
return render_template('loading.html')
def something():
""" The worker function """
global finished
time.sleep(5)
finished = True
@app.route('/result')
def result():
""" Just give back the result of your heavy work """
return 'Done'
@app.route('/status')
def thread_status():
""" Return the status of the worker thread """
return jsonify(dict(status=('finished' if finished else 'running')))
if __name__ == "__main__":
app.run(debug=True)
因此，在您的 loading.html 中，只需插入一个循环Ajax get()请求:
So in your loading.html just insert a cyclic Ajax get() request:
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script>
$(document).ready(function() {
var refresh_id = setInterval(function() {
$.get(
"{{ url_for('thread_status') }}",
function(data) {
console.log(data);
if (data.status == 'finished') {
window.location.replace("{{ url_for('result') }}");
}
}
)}
, 1000);
});
</script>
</head>
<body>
<p>Loading...</p>
</body>
</html>
如果愿意，您甚至可以在进度计数器后面附加它.但是您需要注意防止线程多次运行.
You can even append this by a progress counter if you like. But you need to take care that you prevent the thread from being run multiple times.
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