You may be aware of the uniq method in Ruby:
[1,2,3,4,4,6,2].uniq => [1,2,3,4,6] |
This does not work for arrays of ActiveRecord objects, especially if you want uniqueness on a arbitrary property. Here’s a snippet that allows you to uniquify an Array using an arbitrary property:
Hash[*arrayname.map {|obj| [obj.name, obj]}.flatten].values |
Basically you create a new Hash, using the unique value as the key and the actual object as value. Then you convert the Hash#values back to an Array.
Actually, Ruby uses hashes under the cover when you call #uniq.
And for making arrays uniq on arbitrary properties, use #uniq_by: collection.uniq_by(&:name). This should save you memory.
Or, define the #== method on the objects, if you always uniq by the same property.
Now with rails 3.2 you can use: Product.select(:name).uniq
In 1.9 you can use array.uniq(&:id)