How effectively join ruby hashes recieved from json lists

arr1 = [{ "device"=>100, "phone"=>"12345" },{ "device"=>102, "phone"=>"12346" }]

arr2 = [{ "device"=>100, "type"=>"mobile", "name"=>"nokia" },{ "device"=>102, "type"=>"VIOP", "name"=>"smth" }]

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(arr1 + arr2).group_by { |i| i["device"] }.values.map{|x|x.reduce(&:merge)}

(arr1 + arr2).group_by { |i| i["device"] }.map { |d,(i1,i2)| i1.merge(i2)}