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#2957 ✓resolved
Joey Schoblaska

Adding Array.uniq_by(proc) to core_ext, allowing selection of unique elements based on their response to a proc

Reported by Joey Schoblaska | July 25th, 2009 @ 11:46 PM | in 3.0.2

Oftentimes it's necessary to select some unique elements from an array based on various attributes. For instance, if you have an array of posts and you want to select only posts that have a unique author_id; or posts with a unique combination of author_id and created_at date to get an array with one post per user per day. It's usually possible to do this with SQL when you're dealing with AR objects, but that's not always an option, so I wrote this patch to address those cases.

    array = [{:id => 1, :val => 1}, 
             {:id => 2, :val => 1},
             {:id => 3, :val => 2},
             {:id => 4, :val => 3}]
    array.uniq_by( {|a| a[:val]}).map{|a| a[:id]} == [1,3,4]

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