review

• Through the content of the previous articles, we have built a simple Web application based on the Flask framework. The code of server.py is as follows

  
  

  from flask import Flask, make_response
  from flask.views import MethodView
  app = Flask(__name__)
  
  class IndexHandler(MethodView):
      def get(self):
          resp = make_response('It is a GET request')
          resp.headers['Strict-Transport-Security'] = 'max-age=15768000; includeSubDomains; preload'
          return resp
  
  if __name__ == '__main__':
      app.add_url_rule('/', view_func=IndexHandler.as_view('index'))
      context = ('./server.cer', './server.key')
      app.run(port=443, host='0.0.0.0', debug=True, threaded=True, ssl_context=context)

Abstract out the Page class

• Because we will use HSTS and other common features in the Handler of each Page in the future, we will extract them and abstract them into a Page class. Modify server.py as follows

  
  

  from flask import Flask, make_response
  from flask.views import MethodView
  app = Flask(__name__)
  
  class Page(MethodView):
      def render(self, resp):
          resp.headers['Strict-Transport-Security'] = 'max-age=15768000; includeSubDomains; preload'
          return resp
  
  class IndexHandler(Page):
      def get(self):
          content = 'It is a GET request'
          return self.render(content)
  
  if __name__ == '__main__':
      app.add_url_rule('/', view_func=IndexHandler.as_view('index'))
      context = ('./server.cer', './server.key')
      app.run(port=443, host='0.0.0.0', debug=True, threaded=True, ssl_context=context)

Extract other common properties

• get_args()

  
  

  Args usually appears in GET requests. For example, https://www.google.com/search?q=awesome appears in the address bar when Google searches. The content after? Is args in the form of key value. Corresponding to the previous example, key is Q and value is awesome. If there are multiple groups of key values, use & connection in the middle, such as? Q = awesome & type = server. This form is easy to make We think of Python's dictionary structure, dict File , Flask is through ImmutableMultiDict To store args, we can add the get_args() method to the Page class

  from flask import request
  class Page(MethodView):
      def get_args(self, key):
          return request.args.get(key)

  In this way, we can get the parameters in the user request by calling get ENU args(), for example, chestnut

  
  

  class AwesomeHandler(Page):
      def get(self):
          if self.get_args('q') == 'awesome':
              # do something
              return 'This is an awesome page!'

• Similarly, we can add other features to the Page class, such as get_date(), get_referer(), get_cookies(), etc. the prepared Page class is as follows

  
  

  from flask import request
  from datetime import datetime, date
  
  class Page(MethodView):
      def render(self, resp):
          resp.headers['Strict-Transport-Security'] = 'max-age=15768000; includeSubDomains; preload'
          return resp
  
      def get_args(self, key):
          return request.args.get(key)
  
      def get_date(self, year=0, month=0, day=0):
          if year and month and day:
              return date(year, month, day)
          else:
              return date.today()
  
      def get_referer(self):
          return request.headers.get('referer')
  
      def get_cookies(self):
          return request.cookies

Reference material

• http://flask.pocoo.org/docs/1...