falcon python示例与芹菜

Question

import falcon
import json
from tasks import add
from waitress import serve


class tasksresource:
    def on_get(self, req, resp):
        """Handles GET requests"""
        self.result = add.delay(1, 2)
        self.context = {'ID': self.result.id, 'final result': self.result.ready()}
        resp.body = json.dumps(self.context)



api = falcon.API()
api.add_route('/result', tasksresource())
# api.add_route('/result/task', taskresult())
if __name__ == '__main__':
    serve(api, host='127.1.0.1', port=5555)

如何从json有效负载( post数据)获取任务id并向其添加路由

Answer 1

这里有一个小例子。文件结构：

/project
      __init__.py
      app.py # routes, falcon etc.
      tasks.py # celery 
example.py # script for demonstration how it works 

app.py：

import json

import falcon
from tasks import add
from celery.result import AsyncResult


class StartTask(object):

    def on_get(self, req, resp):
        # start task
        task = add.delay(4, 4)
        resp.status = falcon.HTTP_200
        # return task_id to client
        result = {'task_id': task.id}
        resp.body = json.dumps(result)


class TaskStatus(object):

    def on_get(self, req, resp, task_id):
        # get result of task by task_id and generate content to client
        task_result = AsyncResult(task_id)
        result = {'status': task_result.status, 'result': task_result.result}
        resp.status = falcon.HTTP_200
        resp.body = json.dumps(result)


app = falcon.API()

# registration of routes
app.add_route('/start_task', StartTask())
app.add_route('/task_status/{task_id}', TaskStatus())

tasks.py：

from time import sleep

import celery


app = celery.Celery('tasks', broker='redis://localhost:6379/0', backend='redis://localhost:6379/0')


@app.task
def add(x, y):
    """
    :param int x:
    :param int y:
    :return: int
    """
    # sleep just for demonstration
    sleep(5)

    return x + y

现在我们需要启动celery应用程序。转到project文件夹并运行：

celery -A tasks worker --loglevel=info

之后，我们需要启动Falcon应用程序。转到project文件夹并运行：

gunicorn app:app

好的。一切都准备好了。

example.py是一个小的客户端，它可以帮助理解：

from time import sleep

import requests
# start new task
task_info = requests.get('http://127.0.0.1:8000/start_task')
task_info = task_info.json()

while True:
    # check status of task by task_id while task is working
    result = requests.get('http://127.0.0.1:8000/task_status/' + task_info['task_id'])
    task_status = result.json()

    print task_status

    if task_status['status'] == 'SUCCESS' and task_status['result']:
        print 'Task with id = %s is finished' % task_info['task_id']
        print 'Result: %s' % task_status['result']
        break
    # sleep and check status one more time
    sleep(1)

只需调用python ./example.py，您应该会看到如下所示：

{u'status': u'PENDING', u'result': None}
{u'status': u'PENDING', u'result': None}
{u'status': u'PENDING', u'result': None}
{u'status': u'PENDING', u'result': None}
{u'status': u'PENDING', u'result': None}
{u'status': u'SUCCESS', u'result': 8}
Task with id = 76542904-6c22-4536-99d9-87efd66d9fe7 is finished
Result: 8

希望这对你有帮助。

Answer 2

Danila Ganchar的上述例子很棒，非常有帮助。我在Python 3中使用的是celery版本4.3.0，我在使用上面的示例时收到的一个错误在下面这一行：

task_result = AsyncResult(task_id)

我会收到的错误是：

AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for'

这可能是最近的更改，但result.AsyncResult (在本例中只有AsyncResult，因为他是从celery.result导入的)并不知道您正在使用的后端。有两种解决方案可以解决这个问题：

1)您可以将实际任务本身的AsyncResult取为add.AsyncResult(task_id)，因为add任务已经通过@app.task装饰器定义了后端。在本例中，这样做的缺点是您希望能够通过通过Falcon端点传入task_id来获得任何任务的结果，因此这是有限的

2)首选的方法是只向AsyncResult函数传入app参数：

task = result.AsyncResult(id, app=app)

希望这能有所帮助！