Python - 在服务请求之前访问烧瓶应用程序上下文

Question

用例：我有一个 python 烧瓶应用程序，它在处理路由上的任何请求之前运行 background_function()。

当我执行烧瓶应用程序时，我收到错误 - RuntimeError: Working outside of application context. 我收到错误是因为我尝试在处理任何请求之前获取应用程序上下文。

在此示例中执行background_function() 的最佳pythonic 方式是什么？

from flask import Flask
from download import Download

app = Flask(__name__)

app.config.from_pyfile('config.py')

# run backgroung function
Download.background_function()

@app.route('/')
def index():
    return 'Welcome!'

if __name__ == '__main__':
    app.run()

config 文件

FILE_LOCATION = os.environ['FILE_LOCATION'] # "file/path/on/server"

# Many other variables are present in this file

download 文件

from flask import current_app as app

class Download:

    @staticmethod
    def background_function():
        file_path = app.config["FILE_LOCATION"]
        # code to download file from server to local
    return

Answer 1

试试这个：

from flask import Flask
from download import Download

app = Flask(__name__)

@app.route('/')
def index():
    return 'Welcome!'

if __name__ == '__main__':
    Download.background_function()
    app.run()

download 文件

from flask import current_app as app

class Download:

    @staticmethod
    def background_function():
        print("testing")

给定输出：

testing
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

如您所见，该函数首先运行并打印testing，然后运行应用程序。