boom

app/models/variant_decorator.rb

@@ -0,0 +1,20 @@
+Variant.class_eval do
+  
+  has_one :digital, :dependent => :destroy
+  after_save :destroy_digital, :if => :deleted?
+  
+  # Is this variant to be downloaded by the customer?
+  def digital?
+    digital.present?
+  end
+  
+  private
+  
+  # Spree never deleted Digitals, that's why ":dependent => :destroy" won't work on Digital.
+  # We need to delete the Digital manually here as soon as the Variant is nullified.
+  # Otherwise you'll have orphan Digitals (and their attached files!) associated with unused Variants. 
+  def destroy_digital
+    digital.destroy
+  end
+
+end