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Quick start CherryPy (1)

2022-06-27 09:08:00 【Denglong】

CherryPy It's a lightweight python Network framework , Used to create web applications . Such as rapid implementation api Interface 、 Do the back end of the website . Sense and flask almost .

The simplest example

The following code creates a class “HelloWorld”, Defined a cherryPy Application , And then through quickstart Method to start the application

import cherrypy


class HelloWorld(object):
    @cherrypy.expose
    def index(self):
        return "Hello world!"


if __name__ == '__main__':
    cherrypy.quickstart(HelloWorld())

After execution , Open the browser , You can see the output ”Hello World” word

Implement the second interface

On top of that , We add a second interface , Realize the function of generating random string .

import random
import string

import cherrypy


class StringGenerator(object):
    @cherrypy.expose
    def index(self):
        return "Hello World!"

    @cherrypy.expose
    def generate(self):
        return ''.join(random.sample(string.hexdigits, 8))


if __name__ == '__main__':
    cherrypy.quickstart(StringGenerator())

Then we visit the browser http://127.0.0.1/generate You can see the randomly generated string .

Combined with these two examples, we can see ,@cherrypy.expose Decorator decorated functions will be exposed , Become an independent interface . also ,index Function will be used as interface ’/’ The objective function of the route . The rest of the exposed functions will be routed by their function names .

What if the interface has parameters ？

To implement an interface with parameters , Just specify the parameter name in the input parameter of the function .

The code looks like this ：

import random
import string

import cherrypy


class StringGenerator(object):
    @cherrypy.expose
    def index(self):
        return "Hello World!"

    @cherrypy.expose
    def generate(self, length=16):
        return ''.join(random.sample(string.hexdigits, int(length)))


if __name__ == '__main__':
    cherrypy.quickstart(StringGenerator())

This is the time , If we visit directly http://127.0.0.1:8080/generate The default parameters will be used length=16, Generate a length of 16 String . If we use such a link to access ：

http://127.0.0.1:8080/generate?length=19

Then a length of 19 String .URL The input format of the parameter in is , The first parameter is preceded by a ?, Then each of the following parameters is key=value The format of . If our function has multiple arguments , You only need to add one between the parameters & It can be connected .

Create a simple form

next , We can create a simple form page to enter this length

Our code changes to this ：

import random
import string

import cherrypy


class StringGenerator(object):
    @cherrypy.expose
    def index(self):
        return """<html>
          <head></head>
          <body>
            <form method="get" action="generate">
              <input type="text" value="8" name="length" />
              <button type="submit">Give it now!</button>
            </form>
          </body>
        </html>"""

    @cherrypy.expose
    def generate(self, length=16):
        return ''.join(random.sample(string.hexdigits, int(length)))


if __name__ == '__main__':
    cherrypy.quickstart(StringGenerator())

It should be noted that , The form here uses GET Method , Therefore, the parameter will be added to URL above . Finally generated URL The same format as before .

Enable Session

Session It's very common , We can go through Session To identify the different clients that interact with the server .CherryPy Chinese vs Session Have support . The following code demonstrates that in CherryPy Enable Session Middleware and set it manually Session

import random
import string

import cherrypy


class StringGenerator(object):
    @cherrypy.expose
    def index(self):
        return """<html>
          <head></head>
          <body>
            <form method="get" action="generate">
              <input type="text" value="8" name="length" />
              <button type="submit">Give it now!</button>
            </form>
          </body>
        </html>"""

    @cherrypy.expose
    def generate(self, length=16):
        s = ''.join(random.sample(string.hexdigits, int(length)))
        #  Store in session in 
        cherrypy.session['mystring'] = s
        return s

    @cherrypy.expose
    def display(self):
        return cherrypy.session['mystring']


if __name__ == '__main__':

    conf = {
        '/': {
            'tools.sessions.on': True,   #  stay cherryPy Enable session
        }
    }
    cherrypy.quickstart(StringGenerator(), '/', conf)

In the code above , We are conf Enabled in the dictionary sessions middleware , Then this conf Pass in cherryPy

We first generate a random string , Then save it to Session Of mystring in , Then you can visit display To show this session Field

It should be noted that , By default, the server memory is used to store session Value . in fact ,CherryPy There are also other storage back ends to choose from .

Introduce static files

Our website will contain some static files more or less .cherrypy adopt tools.staticdir It supports the introduction of static files .

First we need to create a static css file , be called style.css Just go . Placed in the current directory public/css/ Under the folder .

style.css:

body {
  background-color: blue;
}

next , We put conf Change the name to ：

conf = {
        '/': {
            'tools.sessions.on': True,   #  stay cherryPy Enable session
            'tools.staticdir.root': os.path.abspath(os.getcwd()),   #  Set the root directory of static files 
        },
        #  Set to static Everything at the beginning is static , And put URL Mapping to public Catalog 
        '/static': {
            'tools.staticdir.on': True,
            'tools.staticdir.dir': './public',   #  Set the folder for static files 
        }

    }

In this code , First of all ’/’ Of all directories at the beginning staticdir Root directory . For security reasons ,CherryPy The path here is required to be absolute .

And then we specify that ’/static’ All of the beginning URL Are static resources , And the corresponding url Mapping to public Catalog .

Finally, we put index Back to html Change it , introduce style.css, You can see the effect . It should be a page with a blue background .（ It's ugly though ）

@cherrypy.expose
    def index(self):
        return """<html>
          <head>
            <link href="/static/css/style.css" rel="stylesheet">
          </head>
          <body>
            <form method="get" action="generate">
              <input type="text" value="8" name="length" />
              <button type="submit">Give it now!</button>
            </form>
          </body>
        </html>"""