Question

如何使用request_finished信号获取和使用HttpRequest？

有兴趣提取用于记录目的的网址。

当前代码如下所示：

import logging

def write_to_file(sender, **kwargs):
    logging.debug(type(sender))
    logging.debug(dir(sender))

from django.core.signals import request_finished
request_finished.connect(write_to_file)

生成此

2010-03-03 13:18:44,602 DEBUG <type 'type'>
2010-03-03 13:18:44,602 DEBUG ['__call__', '__class__', '__delattr__', '__dict__', '__doc__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', '__weakref__', '_get_traceback', 'apply_response_fixes', 'get_response', 'handle_uncaught_exception', 'initLock', 'load_middleware', 'request_class', 'response_fixes']

Answer 1

对于request_finished状态的Django文档，它们提供的类不是实例（不确定原因，提供实例会更有用）。 https://docs.djangoproject.com/en/1.9/ref/signals/#request-finished

所以信号让你知道一个请求已经完成，但不是哪个请求或任何细节。您有2个选项来获取请求。已经提到的一个是将请求存储在中间件中的线程本地存储中。

以下是存储请求的示例。但是你可以使用它来存储最后会被调用的函数。

import collections
import threading

import structlog
from django.utils.cache import patch_vary_headers

logger = structlog.get_logger()

thread_locals = threading.local()


def get_current_request():
    """
    This will return the current request object
    but if the response has been returned the request
    object will be cleaned up
    """
    return getattr(thread_locals, 'request', None)


def request_queue(func, func_id=None, *args, **kwargs):
    """
    Helper function to queue up a function
    and arguments to be run at the end of the request
    if no request, will run straight away
    Usage:
    request_queue(function_to_run, args=(args1, args2), kwargs={'key':'value'})
    """
    request = get_current_request()
    if not request:
        # run the func
        func(*args, **kwargs)
        return
    # else
    # use the supplied id if given
    if not func_id:
        # otherwise use the memory address
        func_id = id(func)
    # store the func and arguments as a tuple under the func id
    request.queue[func_id] = (func, args, kwargs)


class RequestQueueMiddleware(object):
    """
    Use this middleware to get access to the request object
    and to use it to queue functions to run
    """

    def process_request(self, request):
        thread_locals.request = request
        # each request gets a new queue
        request.queue = collections.OrderedDict()

    def process_exception(self, request, exception):
        self.process_queue(request)
        self.cleanup()

    def process_response(self, request, response):
        self.process_queue(request)
        self.cleanup()
        return response

    def cleanup(self):
        try:
            del thread_locals.request
        except AttributeError:
            pass

    def process_queue(self, request):
        if not request:
            request = get_current_request()
        if request and hasattr(request, 'queue'):
            for (func, args, kwargs) in getattr(request, 'queue', {}).itervalues():
                func(*args, **kwargs)
            del request.queue

当您需要访问当前请求时，可以导入函数get_current_request并在任何其他方法中使用。

函数request_queue允许您排队要执行的函数和参数。一个功能是你可以多次排队一个昂贵的功能，它只会被执行一次。

因此，在request_finished处理程序中，您可以调用get_current_request来获取当前请求。但在上面的实现中，您将需要删除清理代码。我不知道将请求对象保留在线程本地存储上是否会泄漏。

不需要任何中间件的另一个选项是检查堆栈帧，直到找到请求为止。

def get_request():
    """Walk up the stack, return the nearest first argument named "request"."""
    frame = None
    try:
        for f in inspect.stack()[1:]:
            frame = f[0]
            code = frame.f_code
            if code.co_varnames and code.co_varnames[0] == "request":
                return frame.f_locals['request']
    finally:
        del frame

如果您有任何其他名为request的变量，它将会中断。也可以适应检查类型。

Answer 2

我想我找到了最简单的解决方案。

在the official Django rep中，我发现requests_finished here的唯一用法。

现在，我可以在manage.py的入口点中轻松覆盖此方法：

from django.http.response import HttpResponseBase

class OverriddenHttpResponseBase:

    @staticmethod
    def close(self):
        for closable in self._closable_objects:
            try:
                closable.close()
            except Exception:
                pass
        self.closed = True
        # here you can access your request using self._closable_objects 

        # you can either send it to request_finished 
        signals.request_finished.send(sender=<whatever data you want>)
        # or code your stuff here without using request_finished at all

if __name__ == '__main__':
    HttpResponseBase.close = OverriddenHttpResponseBase.close

Answer 3

尝试

sender.request_class.get_full_path()

或

sender.request_class._get_request()

或者，如果您想尝试使用middleware执行此操作，正如mountainswhim建议的那样，这里是snippet that demos request timing using middleware。

如何从request_finished信号回调中访问请求？

3 个答案: