Introduction

This item requires that you have the Werkzeug WSGI utilities (version 0.3) installed. Included with Werkzeug is a kick ass debugger that renders nice debugging tracebacks and adds an AJAX based debugger (which allows to execute code in the context of the traceback’s frames). Additionally it provides a nice access view to the source code.

Getting Started

To get started we just use the runserver_plus command instead of the normal runserver command:

python manage.py runserver_plus

 * Running on http://127.0.0.1:8000/
 * Restarting with reloader...
Validating models...
0 errors found

Django version 0.97-newforms-admin-SVN-unknown, using settings 'screencasts.settings'
Development server is running at http://127.0.0.1:8000/
Using the Werkzeug debugger (http://werkzeug.pocoo.org/)
Quit the server with CONTROL-C.

Note: all normal runserver options apply. In other words, if you need to change the port number or the host information, you can do so like you would normally.

Using

Whenever we hit an exception in our code, instead of the normal Django traceback page appearing, we see the Werkzeug traceback page instead.

Along with the typical traceback information we have a couple of options. These options appear when you hover over a particular traceback line. Notice that two buttons appear to the right:

The options are:

View Source

This displays the source below the traceback:

Being able to view the source file is handy because you are able to get more context information around where the error occurred. The actual traceback areas are highlighted so they are easy to spot.

One awkward piece about this is that the page is not scrolled to the bottom. At first I thought nothing was happening because of this.

Interactive Debugging Console

When you click on this button a new pane will open up below the traceback line you're on. This is the money shot:

An ajax based console appears in the pane and you can begin debugging away. Notice in the screenshot above I did a print environ to see what was in the environment parameter coming into the function.

WARNING: This should never be used in any kind of production environment. Not even for a quick check into a problem. I cannot emphasize this enough. The interactive debugger allows you to evaluate python code right against the server. You've been warned.