Flask in Resquest, Responed and technical sessions

Developer Server

• Only for servers used for development of
• It can not be used in the actual project
• advantage
  • More friendly to developers
  • Automatic restart
  • Rich log
  • Debugging page
• Shortcoming
  • Low performance

The method of HTTP request

• GET

  • Acquisition, take
  • Obtain data from a server used, access to resources

• POST

  • submit
  • To submit transfer (submit) to the server
  • Most used in the creation, validation

• DELETE

  • delete
  • Tell the server, I want to delete a resource

• PUT

  • put
  • submit
  • Used to submit data to the server
  • PUT data to update typically

• PATCH

  • patch
  • submit
  • Used to submit data to the server
  • Typically the amount of difference update data used PATCH

Flask setting request method

• Default get support request
• I want to support custom request
  • @app.route("/xxx/", methods=["GET", "POST"])

Router router acquisition

  # python中的写法
  @app.route("/register/", methods=["GET", "POST"])
  def register():
      return
  @app.route("/doregister/", methods=["GET", "POST"])
  # 路由返回的是字符串，可以在返回值里面直接加标签代码：<a>lable</a>
  def do_register():
      return

  {#html 中的写法#}
  <a href="register">login</a>
  <form action="/doregister/" method="post">

Flask of View

• There are two important objects in View

• Double R

  • Request
    • A request sent by a client
    • Which contains a variety of client information
    • Request client is not created
    • Framework is created based on the client's data (request packet)
    • Belonging to the built-in objects in Flask, can not be modified
    • Life Cycle Request: Request from the beginning to the end of Response
    • Request Properties
      • full request url address
      • base url removed GET URL parameters
      • Only host url URL host and port numbers
      • path request path
      • method request method
      • remote addr requesting client address
      • args GET request parameters
      • form POST request parameters
      • File upload files
      • request header headers
      • cookies in the cookie request
  • Response
    • The server returns data to the client
    • Created by the developer
    • There is a variety of ways to create
      • Returns a string directly
        • return 'log in success'
      • Templates can be returned
        • return render_template('login.html')
      • Direct Response object is returned
        • Created directly Response ()
        • May also be used make_response (data, code)
          • The first parameter is the content, the second parameter is the status code

• Type of response

  • Intuitive response to the request

    • return render_template('index.html')

  • Redirect request

    • redirect ( '/') redirected to the root directory (Home)
    • url_for dynamic IP address
    • redirect(url_for('do_register')) do_register is defined routing router

  • Active termination request

    • abort(404)
    • abort(Response('Hello World'))# Response of a WSGI application package

  • Catch the exception

    • @app.errorhandler(404)
      def hello(e):
      	return 'LOL'
      

  Capture POST and GET requests

  • Obtaining parameters via POST
    • username = request.form.get('username') Parameters passed in a form by form
  • Obtaining parameters via GET
    • username = request.args.get('username') Args parameter passed by
  • Analyzing Request
    • if request.method == 'GET' if the request to process the flow control

Technical Session

• Request cycle is very short

• HTTP stateless protocol

  • No protocol for transaction processing and memory

• HTTP connection is short

  • The client and server once for each HTTP operation, once the connection is established, the task is interrupted connection end
    • From HTTP / 1.1 from the default length using TCP connections maintained, for holding connection characteristics

• classification

  • Cookie

    • Client session technology
    • Response written by browser, data is stored in the client
      • response.set_cookie(key,value[max_age=None,exprise=None])
      • request.cookie.get(key)
    • characteristic
      • Cookie default request will carry all of this site
      • Cookie can not cross-site, different domain, different ip
      • Cookie can not cross-browser
      • Cookie stored in key-value
      • Cookie Support expired
        • Flask default browser closed, Cookie expired
        • max_age: integer specifying the cookie expiration time, None never expires
        • expries: integer, can specify a specific date (alternative)
        • Delete cookie response.delete_cookie(key)
      • Shortcoming
        • Unsafe
        • Cleartext

  • Session

    • Session server technology

    • Data is stored on the server

    • characteristic

      • Dependent on Cookie

      • Session key-value store to

        • Set key-value pairs session['username'] = 'value'
        • Get key-value pairs get(key,default=None)
        • Delete key-value pairs pop(key)
        • Clear all clear()

      • Relatively safe

        • app.config["SECRET_KEY"] = "secret_key"

      • You can not cross-site, can not be cross-domain

      • Support expired

        • session.permanent = True
          # permanent_session_lifetime设置过期时间
          session.permanent_session_lifetime = timedelta(days=1)
          

  • Token (does not support Cookie scene)

    • Phone App
    • Session server technology
    • Custom server-side session technology
    • Data storage, query, modify, token (the unique identifier, session_key, session_id) issued entirely controlled by the server

Session scene

• Need to request the presence data across
• Extend the life cycle of the data request