与Django，芹菜和Redis一起安排任务

Question

我在 Celery 中添加了一个用于数据导出的任务。我希望当用户调用Export all按钮时，导出任务开始，前端显示一条 django 消息，而导出在后台继续。但从我的能力来看，我views.py有这个：

def CasesPaluExport(request):
    export_cases_palu.delay(request=request)
    messages.success(request, 'CasesPaluExport')
    return JsonResponse({"Ok": "ok"}, safe=False)

这在tasks.py：

def export_cases_palu(request):
    try:
        plaintext = get_template('stock/download_case_palu.txt')
        htmly = get_template('stock/download_case_palu.html')
        d = Context({'username': request.user.username})
        subject, from_email, to = 'Download all cases palu', settings.DEFAULT_FROM_EMAIL, request.user.email
        text_content = plaintext.render(d)
        html_content = htmly.render(d)
        msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
        msg.attach_alternative(html_content, "text/html")
        msg.send()
    except:
        logging.warning("Tried to send download email to user {0}".format(request.user))

问题是，每当我调用该CasesPaluExport函数时，都会在export_cases_palu.delay(request=request)行出现错误：

Internal Server Error: /user/casepaluexport/
Traceback (most recent call last):
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "/home/user/project/user/views.py", line 170, in CasesPaluExport
    export_cases_palu.delay(request=request)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/celery/app/task.py", line 413, in delay
    return self.apply_async(args, kwargs)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/celery/app/task.py", line 536, in apply_async
    **options
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/celery/app/base.py", line 737, in send_task
    amqp.send_task_message(P, name, message, **options)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/celery/app/amqp.py", line 554, in send_task_message
    **properties
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/messaging.py", line 169, in publish
    compression, headers)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/messaging.py", line 252, in _prepare
    body) = dumps(body, serializer=serializer)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/serialization.py", line 221, in dumps
    payload = encoder(data)
  File "/usr/lib/python2.7/contextlib.py", line 35, in __exit__
    self.gen.throw(type, value, traceback)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/serialization.py", line 54, in _reraise_errors
    reraise(wrapper, wrapper(exc), sys.exc_info()[2])
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/serialization.py", line 50, in _reraise_errors
    yield
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/serialization.py", line 221, in dumps
    payload = encoder(data)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/utils/json.py", line 72, in dumps
    **dict(default_kwargs, **kwargs))
  File "/usr/lib/python2.7/json/__init__.py", line 250, in dumps
    sort_keys=sort_keys, **kw).encode(obj)
  File "/usr/lib/python2.7/json/encoder.py", line 207, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python2.7/json/encoder.py", line 270, in iterencode
    return _iterencode(o, 0)
  File "/home/user/.virtualenvs/project/local/lib/python2.7/site-packages/kombu/utils/json.py", line 62, in default
    return super(JSONEncoder, self).default(o)
  File "/usr/lib/python2.7/json/encoder.py", line 184, in default
    raise TypeError(repr(o) + " is not JSON serializable")
EncodeError: <WSGIRequest: POST '/user/casepaluexport/'> is not JSON serializable
[20/Nov/2017 15:47:56] "POST /user/casepaluexport/ HTTP/1.1" 500 186320

这可能表示服务器仍在等待 http 响应。我该如何解决？

Answer 1

错误告诉您

它无法序列化整个request以将其发送到任务。

但是，您在请求中的任务本身中唯一使用的东西是用户对象。您应该只发送用户 ID，并在任务中获取对象本身。

 export_cases_palu.delay(user_id=request.user.id)

。

def export_cases_palu(user_id):
    user = User.objects.get(id=user_id)
    d = Context({'username': user.username})

(另外，您不应该在尝试中包装整个任务/除非像这样。

Answer 2

第

一件事：每次向芹菜添加或删除任何方法时，都必须重新启动芹菜
第二件事：芹菜在数据库中内部存储(堆栈(方法调用，其参数以 JSON 对象格式，因此您只能在那里传递 JSON 可序列化对象，并且请求不可 JSON 序列化