Sum of hash value inside the array In ruby

Question

I have array like this

data = 
  [
    { :lineItemKey=>57, :sku=>"12GA-RIO",  
      :name=>"12 Gauge", :quantity=>4, :unitPrice=>5.76 },
    { :lineItemKey=>168, :sku=>"22LR-CAS-40-CPRN-50", 
      :name=>"22 Long", :quantity=>2, :unitPrice=>7.6 },
    { :lineItemKey=>57, :sku=>"12GA-RIO", 
      :name=>"12 Gauge", :quantity=>1, :unitPrice=>5.76 }, 
    { :lineItemKey=>236, :sku=>"300BLK-UNWD-CTC-220-BTHP-20",
      :name=>"300 BLK", :quantity=>1, :unitPrice=>31.2 }
  ]

I need to sum the quantity if the sku is same and remove the duplicate. so the output should be like:

data = 
  [
    { :lineItemKey=>57, :sku=>"12GA-RIO", 
      :name=>"12 Gauge", :quantity=>5, :unitPrice=>5.76 },
    { :lineItemKey=>168, :sku=>"22LR-CAS-40-CPRN-50", 
      :name=>"22 Long", :quantity=>2, :unitPrice=>7.6 }, 
    { :lineItemKey=>236, :sku=>"300BLK-UNWD-CTC-220-BTHP-20",
      :name=>"300 BLK", :quantity=>1, :unitPrice=>31.2 }
  ]

Answer 1

Input

data = 
  [
    { :lineItemKey=>57, :sku=>"12GA-RIO", 
      :name=>"12 Gauge", :quantity=>4, :unitPrice=>5.76 },
    { :lineItemKey=>168, :sku=>"22LR-CAS-40-CPRN-50", 
      :name=>"22 Long", :quantity=>2, :unitPrice=>7.6 },
    { :lineItemKey=>57, :sku=>"12GA-RIO", 
      :name=>"12 Gauge", :quantity=>1, :unitPrice=>5.76 }, 
    { :lineItemKey=>236, :sku=>"300BLK-UNWD-CTC-220-BTHP-20",
      :name=>"300 BLK", :quantity=>1, :unitPrice=>31.2 }
  ]

Code

p data.group_by { |x| x[:lineItemKey] }
      .values
      .map { |arr| arr.reduce { |h1, h2| h1.merge(h2) { |k, oldv, newv| k.eql?(:quantity) ? oldv += newv : oldv } } }

Output

[
  { :lineItemKey=>57, :sku=>"12GA-RIO", 
    :name=>"12 Gauge", :quantity=>5, :unitPrice=>5.76 }, 
  { :lineItemKey=>168, :sku=>"22LR-CAS-40-CPRN-50",  
    :name=>"22 Long", :quantity=>2, :unitPrice=>7.6 }, 
  { :lineItemKey=>236, :sku=>"300BLK-UNWD-CTC-220-BTHP-20", 
    :name=>"300 BLK", :quantity=>1, :unitPrice=>31.2 }
]