after_save callback method for secured_image generation lib function

app/models/template.rb

@@ -52,4 +52,13 @@ class Template < ApplicationRecord
   has_many :submissions, dependent: :destroy
 
   scope :active, -> { where(deleted_at: nil) }
+
+  after_save :create_secure_images
+
+  def create_secure_images
+      documents.each do |doc|
+        document_data = doc.blob.download
+        Templates::ProcessDocument.generate_pdf_secured_preview_images(self, doc, document_data)
+      end
+  end
 end