flask 扩展

flask信号（源码）

• 信号

  信号，是在flask框架中为我们预留的钩子，让我们可以进行一些自定义操作。
  pip3 install blinker 
  

根据flask项目的请求流程来进行设置扩展点

• 中间件

  from flask import Flask,render_template
  
  app = Flask(__name__)
  
  
  @app.route('/index')
  def index():
      return render_template('index.html')
  
  
  @app.route('/order')
  def order():
      return render_template('order.html')
  
  
  class MyMiddleware(object):
      def __init__(self,old_app):
          self.wsgi_app = old_app.wsgi_app
  
      def __call__(self, *args, **kwargs):
          print('123')
          result = self.wsgi_app(*args, **kwargs)
          print('456')
          return result
  
  app.wsgi_app = MyMiddleware(app)
  
  if __name__ == '__main__':
      app.run()
  

• 当app_ctx被push到local中栈之后，会触发appcontext_pushed信号，之前注册在这个信号中的方法，就会被执行。

  from flask import Flask,render_template
  from flask import signals
  
  app = Flask(__name__)
  
  @signals.appcontext_pushed.connect
  def f1(arg):
      print('appcontext_pushed信号f1被触发',arg)
  
  @signals.appcontext_pushed.connect
  def f2(arg):
      print('appcontext_pushed信号f2被触发',arg)
  
  @app.route('/index')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
      # app.__call__
  
  

• 执行before_first_request扩展

  from flask import Flask,render_template
  
  app = Flask(__name__)
  
  @app.before_first_request
  def f2():
      print('before_first_requestf2被触发')
  
  @app.route('/index')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• request_started信号

  from flask import Flask,render_template
  from flask import signals
  app = Flask(__name__)
  
  @signals.request_started.connect
  def f3(arg):
      print('request_started信号被触发',arg)
  
  @app.route('/index')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• url_value_processor

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  
  @app.url_value_preprocessor
  def f5(endpoint,args):
      print('f5')
  
  @app.route('/index/')
  def index():
      print('index')
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• before_reuqest

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  @app.before_request
  def f6():
      g.xx = 123
      print('f6')
  
  @app.route('/index/')
  def index():
      print('index')
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• before_render_template / rendered_template

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  @signals.before_render_template.connect
  def f7(app, template, context):
      print('f7')
  
  @signals.template_rendered.connect
  def f8(app, template, context):
      print('f8')
  
  @app.route('/index/')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  
  

• after_request

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  @app.after_request
  def f9(response):
      print('f9')
      return response
  
  @app.route('/index/')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• request_finished

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  @signals.request_finished.connect
  def f10(app,response):
      print('f10')
  
  @app.route('/index/')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• got_request_exception

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  @app.before_first_request
  def test():
      int('asdf')
  
  @signals.got_request_exception.connect
  def f11(app,exception):
      print('f11')
  
  @app.route('/index/')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• teardown_request

  from flask import Flask,render_template,g
  from flask import signals
  app = Flask(__name__)
  
  @app.teardown_request
  def f12(exc):
      print('f12')
  
  @app.route('/index/')
  def index():
      return render_template('index.html')
  
  @app.route('/order')
  def order():
      print('order')
      return render_template('order.html')
  
  if __name__ == '__main__':
      app.run()
  

• request_tearing_down

from flask import Flask,render_template,g
from flask import signals
app = Flask(__name__)

@signals.request_tearing_down.connect
def f13(app,exc):
    print('f13')

@app.route('/index/')
def index():
    return render_template('index.html')

@app.route('/order')
def order():
    print('order')
    return render_template('order.html')

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

• appcontext_popped

from flask import Flask,render_template,g
from flask import signals
app = Flask(__name__)

@signals.appcontext_popped.connect
def f14(app):
    print('f14')

@app.route('/index/')
def index():
    return render_template('index.html')

@app.route('/order')
def order():
    print('order')
    return render_template('order.html')

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

总结：关于flask内部共有14+个扩展点用于我们对flask框架内部进行定制，其中有：9个是信号。

template_rendered = _signals.signal("template-rendered")
before_render_template = _signals.signal("before-render-template")
request_started = _signals.signal("request-started")
request_finished = _signals.signal("request-finished")
request_tearing_down = _signals.signal("request-tearing-down")
got_request_exception = _signals.signal("got-request-exception")
appcontext_tearing_down = _signals.signal("appcontext-tearing-down")
appcontext_pushed = _signals.signal("appcontext-pushed")
appcontext_popped = _signals.signal("appcontext-popped")

message_flashed = _signals.signal("message-flashed")

扩展:flash

flash存值之后只能取一次

from flask import Flask,render_template,flash,get_flashed_messages,session
from flask import signals
app = Flask(__name__)
app.secret_key = 'iuknsoiuwknlskjdf'

@app.route('/index/')
def index():
    # flash('123')
    session['k1'] = 123
    return render_template('index.html')

@app.route('/order')
def order():
    # messages = get_flashed_messages()
    # print(messages)
    val = session['k1']
    del session['k1']
    print(val)
    return render_template('order.html')

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

2.flask-script

flask的组件，用于运行flask程序。

• 安装

  pip3 install flask-script
  

• 使用
  

• 其他执行命令

  from s24day95 import create_app
  from flask_script import Manager
  
  app = create_app()
  manager = Manager(app)
  
  @manager.command
  def custom(arg):
      """
      自定义命令
      python manage.py custom 123
      :param arg:
      :return:
      """
      print(arg)
  
  @manager.option('-n', '--name', dest='name')
  @manager.option('-u', '--url', dest='url')
  def cmd(name, url):
      """
      自定义命令
      执行： python manage.py  cmd -n wupeiqi -u http://www.oldboyedu.com
      :param name:
      :param url:
      :return:
      """
      print(name, url)
  
  if __name__ == '__main__':
      manager.run()