--- attachment.rb.back	2015-06-09 16:15:39.437217094 +0530
+++ attachment.rb	2015-06-09 16:13:29.721406673 +0530
@@ -26,7 +26,8 @@
   validates_length_of :filename, :maximum => 255
   validates_length_of :disk_filename, :maximum => 255
   validates_length_of :description, :maximum => 255
-  validate :validate_max_file_size
+validate :validate_max_file_size, :validate_invalid_file_types
+#validate :validate_max_file_size
 
   acts_as_event :title => :filename,
                 :url => Proc.new {|o| {:controller => 'attachments', :action => 'download', :id => o.id, :filename => o.filename}}
@@ -68,6 +69,24 @@
     end
   end
 
+# madhu code begin
+
+ def validate_invalid_file_types
+
+allowed_type = ['.txt','.csv','.htm','.html','.xml','.css','.doc','.docx','.xls','.xlsx','.rtf','.ppt','.pptx','.pdf','.swf','.flv','.avi','.wmv','.mov','.jpg','.jpeg','.gif','.png']
+a_type=['.txt','.pdf']
+filename = self.filename
+ext = File.extname(filename) 
+if allowed_type.include?(ext)
+puts "#{ext} is valid type"
+else
+#puts "#{ext} is not a valid type"
+errors.add(:base, l(:error_invalid_file_extension))
+end
+end
+
+#madhu code ends
+
   def file=(incoming_file)
     unless incoming_file.nil?
       @temp_file = incoming_file