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A simple WSGI Middleware for compiling CoffeeScript to JavaScript on the fly

Project description


FilterCoffee is a simple WSG middleware for compiling CoffeeScript to JavaScript on the fly. It is intended for use in the development of WSGI applicatons, but for deployed applications you should use some other strategy for delivering your compiled CoffeeScript (e.g., write a script to compile all your CoffeeScripts to JavaScript).

FilterCoffee caches the compiled CoffeeScripts in memory but will recompile scripts when they are modified. A CoffeeScript compilation error results in the request returning a 500 error containing the CoffeeScript error message in the body. Error messages are also output to the wsgi.error stream so that they will show up in your console or in your servers error log.


FilterCoffee depends on CoffeeScript and in turn node.js. CoffeeScript expects the coffee command to be available on the current PATH. See the installation instructions for CoffeeScript for more information:

There are a number of different ways to install CoffeeFilter:

Using PIP

This is the preferred method. Run:

pip install filtercoffee

For an Individual Applicaiton

Copy into an appropriate place in your WSGI applications code.

System Wide from Downloaded Source


python install

Basic Usage

You can wrap your WSGI application in the FilterCoffee middleware like so (assuming that the variable app contains your WSGI application and the variable debug is only set when the application is in development mode:

if debug:
    import filtercoffee
    app = filtercoffee.FilterCoffee(

FilterCoffee will now intercept any request that ends in .js and check if a corresponding .coffee file exists. If a .coffee file exists it will be compiled and the comiled output will be returned in the response (the compiled output is also cached such that recompilation only occurs if the .coffee file changes). If no .coffee file exists, the original application is called to handle the request.

Advanced Usage

FilterCoffee has flexible support for deciding what it should consider a Coffee- or JavaScript. Check the arguments to FilterCoffee’s __init__ method.


0.3 Feb 01, 2012

  • Include README in source distribution

0.2 Jan 25, 2012

  • Documentation Updates

  • PyPI

0.1 Jan 17, 2012

  • Initial release

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