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Editorial Team
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Asked: 2026-06-04T04:29:40+00:00

I have a User model that has a meta column with a hash, for

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I have a User model that has a meta column with a hash, for example {“version”=>”1.0”, “country”=>”UK”}

What is the best practice / efficient way to count each individual values in any key? So I might want to figure out how many records have country = UK or USA or France, etc. I do not know all the possible values in each key beforehand…

I guess I can do it in a big loop

User.all.each do |user|
  user.meta["country"] ..........

but is there a better way to do it?

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1 Answer

  1. Editorial Team

    Yes, there’s group_by

    arr = [{"version" => "1.0", "country" => "UK"},
       {"version" => "1.0", "country" => "France"},
       {"version" => "1.0", "country" => "UK"},
       {"version" => "1.0", "country" => "USA"},
       {"version" => "1.0", "country" => "France"},
       {"version" => "1.0", "country" => "UK"}]
grouped = arr.group_by {|el| el["country"]}
#=> {"UK"=>[{"version"=>"1.0", "country"=>"UK"}, 
#           {"version"=>"1.0", "country"=>"UK"}, 
#           {"version"=>"1.0", "country"=>"UK"}], 
#    "France"=>[{"version"=>"1.0", "country"=>"France"}, 
#               {"version"=>"1.0", "country"=>"France"}], 
#    "USA"=>[{"version"=>"1.0", "country"=>"USA"}]}
grouped.map {|k,v| [k, v.length]}
# => [["UK", 3], ["France", 2], ["USA", 1]]
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