Playing around with removing mongo indexes in standard active record migrations.

000_remove_index_from_mongo_collection.rb

class RemoveIndexFromMongoCollection < ActiveRecord::Migration
  
  def self.up
    remove_mongo_index 'my_collection', 'my_index'
  end

  def self.down
    # Intentionally blank
  end
  
  private
  
  def self.remove_mongo_index(collection, name, raise_on_missing_indexes=false)
    begin
      Mongoid.database.collection(collection).drop_index(name)
    rescue Mongo::MongoDBError => e
      if e.message =~ /index not found/
        message = "Couldn't find the '#{name}' index in the '#{collection}' collection."
        raise_on_missing_indexes ? raise("ERROR: #{message}") : puts("WARNING: #{message}")
      else
        raise e
      end
    end
  end
  
end