MapReduce with Mongoose and CoffeeScript

After searching the InterWeb for a decent MapReduce example coded in CoffeeScript I came up blank and decided to write my own. This one uses Mongoose too - well why use anything else?

I haven't written a whole lot of explanation in the text, but commented the code quite heavily so you can copy and paste and still have it with you.


Load Mongoose and connect to your database.Describe your schema and model and then load up some dummy data.

Now for the MapReduce stuff. If you still don't get MapReduce then you will once you read this Star Trek based article.

Define a Map function.

Define a Reduce function.

Get some output

The results will now be in a collection called "results" which you can look at with JMongoBrowser or whatever.

I hope this is of some use to you. If there are any corrections or improvements then please post something below.

Staying Up Late - CoffeeScript and Zappa

Over the last couple of years NodeJS has become the darling of "coding for pleasure" crowd. All that cross fertilization from the client side buffs into the server side and the server side coders ranting about the whole event-driveness of NodeJS.

Yes, it's the next big thing. Well, it's probably not, but it's certainly "A" next big thing or maybe we'll all get bored dream up something else with a catchy name... "perl for parallelism" or "Friendly Java (without the memory leaks)", or what about "C+=3" or "Oil for Android", "Lube for Palm OS". Well you know what I mean.

We see something; we explore it and once it starts getting a bit boring we convince ourselves and then our customers that we need to use some new technology or other. It's all true of course, or partly true, or lies.

Anyway, I'm not here to rant about that, after all I as guilty as anyone else.

A Messy Affair

What I want to rant about is Zappa which is my own personal cure for technical disfunction at the moment. Well that sounds real bad, but I've been doing this job for years and it's only these little affairs over the years that keep me coming home; "Assembler", "C", "C++", "Ruby", "Python", how I remember their sweet names, but sooner or later they all start to look like their mother and have to go.

Zappa is a young virgin of a technology, only now reaching a pubescent version 0.3. Essentially it's a lightweight framework built on top of known technologies such like NodeJS, CoffeeScript, Express and Socket.IO in much the same way as Python's Flask is built on top of Werkzeug, Jinja 2 and so on.

It's that Socket.IO bit that makes this one so sexy (I'm overdoing the procreation metaphors aren't I?). Socket.IO provides cross-browser WebSocket goodness which means you can do stuff like stop using the Model-View-Controller paradigm and start thinking outside the cubical with your "Model-View-Controller-View-Controller-Controller-View Paradigm" or whatever. Mind you, that's when you'll realise that MVC wasn't about limiting your options, it was about simplifying them.

Anyway, back to Zappa itself. Go and have a look, there are great examples that will get your inventive juices flowing (stop it!) and inspire you to spend a little time alone locked it the bathroom... I mean office. The community is starting to grow and the mailing list is big enough to be useful, but not so big as to be faceless and scarey.

Have fun but take precautions.