summary HOWTO create a really simple web application using snake-guice

Experimental features not available in the public release. The API is highly volitile.

Warning this document is a brain dump and not necessarily organized properly.

Warning this document assumes that you are using a UNIX variant and Python 2.5 or above - this will work for other platforms and/or older versions of Python, but the instructions would vary a little.

Basic Steps

You must decide where you want your web application. For this tutorial I'll assume you'll be using $HOME/src/mywebapp.

cd $HOME mkdir src cd src

I'll be using [[http:// virtualenv]] to create an isolated environment for our webapp. We first need to download it. I prefer to get it directly from its Subversion trunk.

wget http://svn.colorstudy.com/virtualenv/trunk/virtualenv.py

New lets use virtualenv to create our environment and activate the environment.

python virtualenv.py mywebsite cd mywebsite . bin/activate

I really like using [WebOb] and [[http:// Routes]] so I'm going to install them now along with snake-guice.

easy_install webob routes snake-guice

The actual source files for the webapp will be stord in a src directory. So we'll create that now. mkdir src cd src

We now need to create the controller class that will actually handle to request. Create a file named controllers.py and paste in the following code:

``` from webob import Response

class EntryController(object):

def index(self, request):
    return Response('This is your default action. '
            'You may show a list of entries here.')

def show(self, request, id):
    return Response('You are looking at entry #%s.' % id)

def new(self, request):
    return Response('In a more fully featured example you would be '
                    'adding a new record to the database.')

def update(self, request, id):
    return Response('In a more fully featured example you would be '
                    'updating record #%s in the database.' % id)

```

Lets wire up the EntryController using snake-guice. Create a file named app.py and paste in the following code: ``` from wsgiref.simple_server import make_server

from controllers import EntryController from snakeguice import Injector from snakeguice.extras.modules.snakeroutes import ( RoutesBinder, RoutesModule, Application)

class Module(RoutesModule):

def configure_mapper(self, binder):
    binder.connect('/entries', controller=EntryController, action='index')
    binder.connect('/entries/new', controller=EntryController, action='new')
    binder.connect('/entry/:id/:action', controller=EntryController)

injector = Injector(Module()) app = Application(injector)

httpd = make_server('', 8000, app) print "Serving on port 8000..." httpd.serve_forever() ```

Trying running it now: python app.py

You now have a web server listening on port 8000. Trying hitting one of the following URLs in you web browser: * http://localhost:8000/entries * http://localhost:8000/entries/new * http://localhost:8000/entry/123/show * http://localhost:8000/entry/123/update

Other Notes

There is some support for virtual hosting using the annotation property of your binder. This is still a bit complicated so I'll have to document it later. The general idea is that you would be able to serve multiple sites, each with a separate mapper, from within the same process.