Prevent Browsers from caching downloaded documents

app/controllers/dmsf_controller.rb

@@ -88,6 +88,8 @@ class DmsfController < ApplicationController
   end
 
   def download_email_entries
+    # IE has got a tendency to cache files
+    expires_in(0.year, "must-revalidate" => true)
     send_file(
         params[:path],
         :filename => 'Documents.zip',

app/controllers/dmsf_files_controller.rb

@@ -65,6 +65,8 @@ class DmsfFilesController < ApplicationController
       else
         title_format = Setting.plugin_redmine_dmsf['dmsf_global_title_format']
       end
+      # IE has got a tendency to cache files
+      expires_in(0.year, "must-revalidate" => true)
       send_file(@revision.disk_file,
         :filename => filename_for_content_disposition(@revision.formatted_name(title_format)),
         :type => @revision.detect_content_type,

app/controllers/dmsf_public_urls_controller.rb

@@ -30,6 +30,8 @@ class DmsfPublicUrlsController < ApplicationController
     if dmsf_public_url
       revision = dmsf_public_url.dmsf_file.last_revision
       begin
+        # IE has got a tendency to cache files
+        expires_in(0.year, "must-revalidate" => true)
         send_file(revision.disk_file,
                   :filename => filename_for_content_disposition(revision.name),
                   :type => revision.detect_content_type,