Validate length of some product fields

We know if the values are too long, so let's provide a useful message rather than generating an unhandled database error.
This code seems rather repetetive, it would be good to use a shared module. I wonder if there's a gem for that.

Note that the existing /products/*/edit screen doesn't even handle validation errors yet, but that's something for another day..

app/models/spree/product.rb

@@ -54,7 +54,8 @@ module Spree
     has_many :variant_images, -> { order(:position) }, source: :images,
                                                        through: :variants
 
-    validates :name, presence: true
+    validates :name, presence: true, length: { maximum: columns_hash['name'].limit }
+    validates :sku, length: { maximum: columns_hash['sku'].limit }
 
     validates :variant_unit, presence: true
     validates :unit_value, numericality: {

spec/models/spree/product_spec.rb

@@ -163,6 +163,10 @@ module Spree
         expect(build(:product)).to be_valid
       end
 
+      it { is_expected.to validate_presence_of :name }
+      it { is_expected.to validate_length_of(:name).is_at_most(255) }
+      it { is_expected.to validate_length_of(:sku).is_at_most(255) }
+
       it "requires a primary taxon" do
         expect(build(:simple_product, primary_taxon: nil)).not_to be_valid
       end