[problem description]

The author encountered a classic error in flash. The error information is as follows:

[problem analysis]

application context is the application context of Flask, which contains variables such as app and g. When it is not convenient to operate app, we use current_app instead of app. current_app can only be accessed when processing requests, and I used current_app outside of processing requests, so an error was reported. Specifically, I used current_app in a custom tool class, ran the program, and could not get the application context when the program loaded the tool class, so the error was reported. The error code is as follows.

[problem-solving]

Since you can’t use current_app in the class property in the tool class, comment out the code and put it in the class method, and modify it as follows. The class method defined by me is used in the view, so the current_app is used in the view when processing the request, so no error will be reported and the problem is solved.