蓝图初始化，我可以在第一次请求蓝图之前运行一个函数吗

问题描述

是否可以在对特定 blueprint 的首次请求之前运行功能?

Is it possible to run a function before the first request to a specific blueprint?

@my_blueprint.before_first_request
def init_my_blueprint():
    print 'yes'

当前，这将产生以下错误:

Currently this will yield the following error:

AttributeError: 'Blueprint' object has no attribute 'before_first_request'

推荐答案

该蓝图等效项称为 @ Blueprint.before_app_first_request :

The Blueprint equivalent is called @Blueprint.before_app_first_request:

@my_blueprint.before_app_first_request
def init_my_blueprint():
    print('yes')

该名称反映出它在任何请求之前被调用，而不仅仅是该蓝图的特定请求.

The name reflects that it is called before any request, not just a request specific to this blueprint.

对于要由您的蓝图处理的第一个请求，没有钩子来运行代码.您可以使用 @ Blueprint.before_request 处理程序进行模拟a>测试它是否已经运行:

There is no hook for running code for just the first request to be handled by your blueprint. You can simulate that with a @Blueprint.before_request handler that tests if it has been run yet:

from threading import Lock

my_blueprint._before_request_lock = Lock()
my_blueprint._got_first_request = False

@my_blueprint.before_request
def init_my_blueprint():
    if my_blueprint._got_first_request:
        return
    with my_blueprint._before_request_lock:
        if my_blueprint._got_first_request:
            return

        # first request, execute what you need.
        print('yes')

        # mark first request handled *last*
        my_blueprint._got_first_request = True

这模仿了Flask在这里所做的事情；需要锁定，因为单独的线程可以争先获得职位.

This mimics what Flask does here; locking is needed as separate threads could race to the post to be first.

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