add database constraint for variant unit_value

db/migrate/20210414171109_add_unit_value_constraint.rb

@@ -0,0 +1,10 @@
+class AddUnitValueConstraint < ActiveRecord::Migration[5.0]
+  def up
+    execute "UPDATE spree_variants SET unit_value = 1 WHERE unit_value <= 0"
+    execute "ALTER TABLE spree_variants ADD CONSTRAINT positive_unit_value CHECK (unit_value > 0)"
+  end
+
+  def down
+    execute "ALTER TABLE spree_variants DROP CONSTRAINT positive_unit_value"
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20210326094519) do
+ActiveRecord::Schema.define(version: 20210414171109) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"