By CherryPy Team

In the previous tutorial, we have seen how to create an application that could generate a random string. Let’s now assume you wish to indicate the length of that string dynamically.

import random
import string

import cherrypy


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

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


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

Go now to http://localhost:8080/generate?length=16 and your browser will display a generated string of length 16. Notice how we benefit from Python’s default arguments’ values to support URLs such as http://localhost:8080/generate still. 

In a URL such as this one, the section after ? is called a query-string. Traditionally, the query-string is used to contextualize the URL by passing a set of (key, value) pairs. The format for those pairs is key=value. Each pair being separated by a & character. 

Notice how we have to convert the given length value to an integer. Indeed, values are sent out from the client to our server as strings. 

Much like CherryPy maps URL path segments to exposed functions, query-string keys are mapped to those exposed function parameters.