Flask-1-06-script extension

Before learning extensions, first introduced a few concepts, their own ideas is not very clear, we do not have the means to do too much to explain

Request context and application context

Context Request (request context)

• request

• session

Application context (application context)

• current_app

• G (processing the request, the object for temporary storage, the reset every request variable)

Request hook

Hook request is implemented in the form of decorators, the Flask support hooks following four request:

 

• before_first_request : Run before processing the first request. @ app.before_first_request

 

• before_request : run before each request. @ app.before_request

 

• after_request (Response) : If there are no unhandled exception is thrown, run after each request. @ app.after_request

 

• teardown_request (Response) : after each request to run, even with an unhandled exception is thrown. @ app.teardown_request  Notes: need in production mode, that is, when debug = False

Simple example:

 

# Coding: UTF-. 8 

from Flask Import the Flask 

App = the Flask ( the __name__ ) 


@ app.route ( " / index " )
 DEF index ():
     Print ( " index performed " )
     return  ' index Page ' 


@ app.before_first_request 
DEF before_first_request_function ():
     "" " to be executed before the first request processing " "" 
    Print ( " the before the implementation of the first request function " ) 


@ app.before_request 
DEFbefore_request_function ():
     "" " are performed before each request " "" 
    Print ( " before execution of the function Request " ) 


@ app.after_request 
DEF after_request_function (Response):
     "" " in each request (function processing view) after have been executed, provided that the view function does not appear abnormal "" " 
    Print ( " the after request function performed " )
     return the Response 


@ app.teardown_request 
DEF teardown_request_function (the Response):
     " "" in every request (view function processing) after They have been executed, regardless of the view function is abnormal, have been executed, work in non-debug mode = False debug "" "
    Print ( " tearDown Request function performed")


if __name__ == '__main__':
    app.run(host='0.0.0.0')

 

# Show results 
(Flask_py) @ Python Python-VirtualBox: ~ / code $ Python hook_demo.py 
  * Running ON http://0.0.0.0:5000/ (Press CTRL + C to quit) 
the before First Request function is executed 
before request function execution the 
index performed 
after request function performed 
teardown request function performed
 127.0.0.1 - - [24 / Jul-/ 2019 19:39:20] " the GET / index the HTTP / 1.1 " 200 is -

 

 

Flask-Script Extended Script

---

 

installation

pip install Flask-Script

Add the startup script Manager

# Coding: UTF-8 

from the Flask Import the Flask
 from flask_script Import Manager    # start command Management 


App = the Flask ( __name__ ) 

# Create Object Manager management class 
Manager = Manager (App) 


@ app.route ( " / index " )
 DEF index ():
     return  " index Page " 


IF  __name__ == ' __main__ ' :
     # app.run (Debug = True) 
    # to start the flask through the management objects 
    manager.run ()

Before we start the terminal can view the help information help

(Flask_py) python@python-VirtualBox:~/code$ python flask_scirpt_demo.py --help
usage: flask_scirpt_demo.py [-?] {shell,runserver} ...

positional arguments:
  {shell,runserver}
    shell            Runs a Python shell inside Flask application context.
    runserver        Runs the Flask development server i.e. app.run()

optional arguments:
  -?, --help         show this help message and exit

As it can be seen there are two commands we can choose from, runserver again to view the selected help information help

(Flask_py) python@python-VirtualBox:~/code$ python flask_scirpt_demo.py runserver --help
usage: flask_scirpt_demo.py runserver [-?] [-h HOST] [-p PORT] [--threaded]
                                      [--processes PROCESSES]
                                      [--passthrough-errors] [-d] [-D] [-r]
                                      [-R]

Runs the Flask development server i.e. app.run()

optional arguments:
  -?, --help            show this help message and exit
  -h HOST, --host HOST
  -p PORT, --port PORT
  --threaded
  --processes PROCESSES
  --passthrough-errors
  -d, --debug           enable the Werkzeug debugger (DO NOT use in production
                        code)
  -D, --no-debug        disable the Werkzeug debugger
  -r, --reload          monitor Python files for changes (not 100{'const':
                        True, 'help': 'monitor Python files for changes (not
                        100% safe for production use)', 'option_strings':
                        ['-r', '--reload'], 'dest': 'use_reloader',
                        'required': False, 'nargs': 0, 'choices': None,
                        'default': None, 'prog': 'flask_scirpt_demo.py
                        runserver', 'container': <argparse._ArgumentGroup
                        object at 0x7f2a3e8db290>, 'type': None, 'metavar':
                        None}afe for production use)
  -R, --no-reload       do not monitor Python files for changes

Start and designated host: 0.0.0.0 port: 12345 and 127.0.0.1 or accessed via local ip 

(Flask_py) python@python-VirtualBox:~/code$ python flask_scirpt_demo.py runserver -h 0.0.0.0 -p 12345
 * Running on http://0.0.0.0:12345/ (Press CTRL+C to quit)
127.0.0.1 - - [24/Jul/2019 20:00:43] "GET /index HTTP/1.1" 200 -
127.0.0.1 - - [24/Jul/2019 20:00:43] "GET /favicon.ico HTTP/1.1" 404 -

 The results show:

In addition runserver this option there is a shell of this option

Ipython this is to enter the compiler where you do not need to import flask_script_demo This module can be used directly with it