MongoDB Group using Ruby driver

Question

I\'m trying to bring back a list of year/month combinations with counts for describing blog posts. The idea is that they will be displayed like so:

• January 201

Answer 1

That's pretty strange behavior. I just ran your code locally, and everything worked. Can you verify that you're using the driver version 0.18.2? If so, make sure that that's the only version installed (just as a sanity check).

I don't think it should make any difference, but I wasn't running #group from MongoMapper -- I was using the gem alone. You might try that, too. Here's the code I ran:

require 'rubygems'
require 'mongo'

d = Mongo::Connection.new.db('blog')
c = d['post']

p c.group("function(x) { return { month: x.date.getMonth(), year:x.date.getFullYear() }; }", 
  nil, 
  { :count => 0 }, 
  "function(x,y){y.count++}", 
  true)