Getting started with cherrypy

Remarks#

This section provides an overview of what cherrypy is, and why a developer might want to use it.

It should also mention any large subjects within cherrypy, and link out to the related topics. Since the Documentation for cherrypy is new, you may need to create initial versions of those related topics.

Installation instructions

Preconditions

These instructions suppose you have any type of Linux, Unix, Mac with bash or Git-bash Windows.
Windows: Download and install Git-bash for Windows, then execute ‘bash’ from command line.
Other shells than bash are fine too, just replace the activate command below with activate.csh or Google: ”virtualenv activate your-shell-name“.

Before you start, check that Python, virtualenv and pip are installed:

$ python --version
$ virtualenv --version
$ pip --version

Install

Create a directory with your web/app, create environment and install CherryPy package.

$ mkdir /develop/myapp/
$ cd /develop/myapp/
$ virtualenv venv
$ source venv/bin/activate
- On Windows in Git-bash: $ source venv/Scripts/activate
(venv) $ pip install cherrypy
(venv) $ python

Python 3.5.2 ...
>>> import cherrypy
>>> cherrypy
<module 'cherrypy' from '... venv/site-packages/cherrypy/__init__.py'>

Congratulations! Now you are ready for your first CherryPy application.

Hello world in CherryPy

If you have a virtualenv and CherryPy is already installed in it, create a file hello.py:

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

import cherrypy

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

    @cherrypy.expose
    def greet(self, name):
        return 'Hello {}!'.format(name)

cherrypy.quickstart(HelloWorld())

Then execute the file: $ hello.py or $ python hello.py. You should see output similar to this:

user@computer /develop/myapp $ python hello.py
[06/Nov/2016:05:58:44] ENGINE Listening for SIGTERM.
[06/Nov/2016:05:58:44] ENGINE Bus STARTING
[06/Nov/2016:05:58:44] ENGINE Set handler for console events.
CherryPy Checker:
The Application mounted at '' has an empty config.

[06/Nov/2016:05:58:44] ENGINE Started monitor thread '_TimeoutMonitor'.
[06/Nov/2016:05:58:44] ENGINE Started monitor thread 'Autoreloader'.
[06/Nov/2016:05:58:45] ENGINE Serving on https://127.0.0.1:8080
[06/Nov/2016:05:58:45] ENGINE Bus STARTED

To see ‘Hello World!’ point your browser to https://localhost:8080/
To see a greeting, go to https://localhost:8080/greet?name=John

File upload with CherryPy

This example consists of three parts:

server.py - CherryPy application that can receive and save a file.
webpage.html - Example how to upload a file to server.py from a webpage.
cli.py - Example how to upload a file to server.py from a command line tool.
Bonus - upload.txt - file that you will upload.

server.py

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

import os
import cherrypy

config = {
    'global' : {
        'server.socket_host' : '127.0.0.1',
        'server.socket_port' : 8080
    }
}


class App:

    @cherrypy.expose
    def upload(self, ufile):
        # Either save the file to the directory where server.py is
        # or save the file to a given path:
        # upload_path = '/path/to/project/data/'
        upload_path = os.path.dirname(__file__)

        # Save the file to a predefined filename
        # or use the filename sent by the client:
        # upload_filename = ufile.filename
        upload_filename = 'saved.txt'

        upload_file = os.path.normpath(
            os.path.join(upload_path, upload_filename))
        size = 0
        with open(upload_file, 'wb') as out:
            while True:
                data = ufile.file.read(8192)
                if not data:
                    break
                out.write(data)
                size += len(data)
        out = '''
File received.
Filename: {}
Length: {}
Mime-type: {}
''' .format(ufile.filename, size, ufile.content_type, data)
        return out


if __name__ == '__main__':
    cherrypy.quickstart(App(), '/', config)

webpage.html

<form method="post" action="https://127.0.0.1:8080/upload" enctype="multipart/form-data">
    <input type="file" name="ufile" />
    <input type="submit" />
</form>

cli.py

This example requires Python requests package, however file can be sent to server in plain Python.

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

import requests

url = 'https://127.0.0.1:8080/upload'
files = {'ufile': open('file.txt', 'rb')}

r = requests.post(url, files=files)

print(r)
print(r.text)

upload.txt

Hello! This file was uploaded to CherryPy.

Upload from browser

Run $ server.py
Open webpage.html in your web browser.
After you select file from your drive and submit it, it will be saved as saved.txt.

Upload from command line

Open one console and run $ server.py
Open another console and run $ cli.py
- Note: Test file upload.txt should be in the same directory with cli.py
File upload.txt should be uploaded and saved as saved.txt.