CherryPy - ToolBox


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Within CherryPy, built-in tools offer a single interface to call the CherryPy library. The tools defined in CherryPy can be implemented in the following ways −

  • From the configuration settings
  • As a Python decorator or via the special _cp_config attribute of a page handler
  • As a Python callable that can be applied from within any function

Basic Authentication Tool

The purpose of this tool is to provide basic authentication to the application designed in the application.

Arguments

This tool uses the following arguments −

Name Default Description
realm N/A String defining the realm value.
users N/A Dictionary of the form − username:password or a Python callable function returning such a dictionary.
encrypt None Python callable used to encrypt the password returned by the client and compare it with the encrypted password provided in the users dictionary.

Example

Let us take an example to understand how it works −

import sha
import cherrypy

class Root:
@cherrypy.expose
def index(self):

return """
<html>
   <head></head>
   <body>
      <a href = "admin">Admin </a>
   </body>
</html>
""" 

class Admin:

@cherrypy.expose
def index(self):
return "This is a private area"

if __name__ == '__main__':
def get_users():
# 'test': 'test'
return {'test': 'b110ba61c4c0873d3101e10871082fbbfd3'}
def encrypt_pwd(token):

return sha.new(token).hexdigest()
   conf = {'/admin': {'tools.basic_auth.on': True,
      tools.basic_auth.realm': 'Website name',
      'tools.basic_auth.users': get_users,
      'tools.basic_auth.encrypt': encrypt_pwd}}
   root = Root()
root.admin = Admin()
cherrypy.quickstart(root, '/', config=conf)

The get_users function returns a hard-coded dictionary but also fetches the values from a database or anywhere else. The class admin includes this function which makes use of an authentication built-in tool of CherryPy. The authentication encrypts the password and the user Id.

The basic authentication tool is not really secure, as the password can be encoded and decoded by an intruder.

Caching Tool

The purpose of this tool is to provide memory caching of CherryPy generated content.

Arguments

This tool uses the following arguments −

Name Default Description
invalid_methods ("POST", "PUT", "DELETE") Tuples of strings of HTTP methods not to be cached. These methods will also invalidate (delete) any cached copy of the resource.
cache_Class MemoryCache Class object to be used for caching

Decoding Tool

The purpose of this tool is to decode the incoming request parameters.

Arguments

This tool uses the following arguments −

Name Default Description
encoding None It looks for the content-type header
Default_encoding "UTF-8" Default encoding to be used when none is provided or found.

Example

Let us take an example to understand how it works −

import cherrypy
from cherrypy import tools

class Root:
@cherrypy.expose
def index(self):

return """ 
<html>
   <head></head>
   <body>
      <form action = "hello.html" method = "post">
         <input type = "text" name = "name" value = "" />
         <input type = ”submit” name = "submit"/>
      </form>
   </body>
</html>
"""

@cherrypy.expose
@tools.decode(encoding='ISO-88510-1')
def hello(self, name):
return "Hello %s" % (name, )
if __name__ == '__main__':
cherrypy.quickstart(Root(), '/')

The above code takes a string from the user and it will redirect the user to "hello.html" page where it will be displayed as “Hello” with the given name.

The output of the above code is as follows −

Decoding Tool
hello.html

Decoding Tool Output

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