desired array

{"Sale Date"=>"7/24/2016",
  "Item price"=>"$30.00",},
  {"Sale Date"=>"7/24/2016",
  "Item price"=>"$60.00",},
  {"Sale Date"=>"7/25/2016",
  "Item price"=>"$10.00",},
    {"Sale Date"=>"7/25/2016",
  "Item price"=>"$20.00",},
  
  etc...

self.hash

 {"Sale Date"=>"7/24/2016",
  "Client"=>"Amajor, Caitlin",
  "Sale ID"=>"58198",
  "Item name"=>"$30 for 30 (NEW STUDENTS ONLY)",
  "Sales Notes"=>nil,
  "Location"=>"Online Store",
  "Notes"=>nil,
  "Color"=>"---",
  "Size"=>"---",
  "Item price"=>"$30.00",
  "Quantity"=>"1",
  "Subtotal"=>"$30.00",
  "Discount %"=>"0.00",
  "Discount amount"=>"$0.00",
  "Tax"=>"$0.00",
  "Item Total"=>"$30.00",
  "Total Paid w/ Payment Method"=>"$30.00",
  "Payment Method"=>"Credit card (Visa/MC-Keyed)"},

sheet.rb

  def sort_by(key)
    self.hash.sort_by{ |row| row[key] }
  end

  def sort_by_date_and(key)
    hash = self.hash.sort_by{ |row| row["Sale Date"] }
    # sorted by Sale Date, what now?
    # Want to sort by date, and then within each date sort by another key such as "Item price"
  end