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python - Flask：RuntimeError：在请求上下文之外工作

问题描述

我正在尝试用 ROS 和烧瓶控制机器人。问题是当我用 ctrl-c (SIGINT) 杀死 ROS 时，烧瓶会减慢这个过程，因为它没有立即关闭。我已经实现了一个 signal_handler 来处理 ctrl-c 并关闭烧瓶。

问题是当我运行它并按下

ctrl-c i 立即关闭所有内容，但出现以下错误：

RuntimeError：在请求上下文之外工作。

我该如何解决这个错误？

#!/usr/bin/env python

import rospy
from raspimouse_ros.msg import MotorFreqs
from time import sleep
from flask import Flask, request
from os.path import join, dirname
from signal import signal, SIGINT

cwd = dirname(__file__)
open(join(cwd, "file.html"))

app = Flask(__name__)

deltaX = 0
deltaY = 0

pub = rospy.Publisher('/motor_raw', MotorFreqs, queue_size=10)
rospy.init_node('control')

msg = MotorFreqs()

def signal_handler(signal_received, frame):
    msg.left = 0
    msg.right = 0
    pub.publish(msg)
    print("Quitting .......")
    func = request.environ.get('werkzeug.server.shutdown')
    func()

signal(SIGINT,signal_handler)

@app.route("/")
def main():
    with open(join(cwd, "file.html"), 'r') as f:
        program = f.read()
    return program

@app.route("/SetSpeed")
def SetSpeed():
    global deltaX
    global deltaY
    deltaX = int(float(request.args.get('x')) * 4)
    deltaY = int(float(request.args.get('y')) * 10)
    publisher()
    return ""

def publisher():
    msg.left = int(-deltaY+deltaX)
    msg.right = int(-deltaY-deltaX)
    rospy.loginfo(msg)
    pub.publish(msg) 

app.run(host="0.0.0.0")

[control-1] killing on exit
Quitting .......
Traceback (most recent call last):
  File "/home/pi/workspace/src/manual_control/scripts/control.py", line 54, in <module>
    app.run(host="0.0.0.0")
  File "/usr/lib/python2.7/dist-packages/flask/app.py", line 841, in run
    run_simple(host, port, self, **options)
  File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 708, in run_simple
    inner()
  File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 673, in inner
    srv.serve_forever()
  File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 511, in serve_forever
    HTTPServer.serve_forever(self)
  File "/usr/lib/python2.7/SocketServer.py", line 231, in serve_forever
    poll_interval)
  File "/usr/lib/python2.7/SocketServer.py", line 150, in _eintr_retry
    return func(*args)
  File "/home/pi/workspace/src/manual_control/scripts/control.py", line 28, in signal_handler
    func = request.environ.get('werkzeug.server.shutdown')
  File "/usr/lib/python2.7/dist-packages/werkzeug/local.py", line 343, in __getattr__
    return getattr(self._get_current_object(), name)
  File "/usr/lib/python2.7/dist-packages/werkzeug/local.py", line 302, in _get_current_object
    return self.__local()
  File "/usr/lib/python2.7/dist-packages/flask/globals.py", line 37, in _lookup_req_object
    raise RuntimeError(_request_ctx_err_msg)
RuntimeError: Working outside of request context.

This typically means that you attempted to use functionality that needed
an active HTTP request.  Consult the documentation on testing for
information about how to avoid this problem.
shutting down processing monitor...
... shutting down processing monitor complete
done

标签： pythonpython-2.7flask

解决方案

请求上下文在请求到达时处于活动状态，并在完成后被销毁，因此它在signal_handler函数中不可用，但是您可以访问app_context.

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