See existing indexes in MongoDB using mongoid

Question

I'd like to see the existing indexes used by MongoDB. Can I do the equivalent of

$ mongod
> use my_db
> db.system.indexes.find()

using Mongoid?

$ rails console
> ?

Would be convenient from my heroku apps using MongoHQ. Thanks!

Answer 1

You can get at the underlying indexes for a Mongoid model through its collection.

> YourModel.collection.indexes

This reaches down into the moped driver (in Mongoid 3). See http://mongoid.org/en/moped/docs/driver.html

Answer 2

To put Steve's answer to use, I added it to a module to do "common things":

module CommonModelMethods
  extend ActiveSupport::Concern
  class_methods do
    def show_indexes
      self.collection.indexes.to_a.collect{|i| i[:key]}
    end
  end
end

That module can then be included in your class (useful during development):

class WaterSupply
  include Mongoid::Document
  include CommonModelMethods
  ...
end

Which can result in something like this in the console:

2.4.5 :031 > WaterSupply.show_indexes
 => [{"_id"=>1}, {"location"=>"2dsphere"}, {"address"=>1}, {"organization_id"=>1, "address"=>1}]