Initial line item idea

app/models/line_item.rb

@@ -0,0 +1,7 @@
+class LineItem < ApplicationRecord
+  belongs_to :issue
+
+  validates :description, presence: true
+  validates :quantity, numericality: { greater_than: 0 }
+  validates :unit_price, numericality: { greater_than_or_equal_to: 0 }
+end