--- a/sdi/forms.py	Sat May 29 15:39:55 2010 +0530
+++ b/sdi/forms.py	Sat May 29 15:46:00 2010 +0530
@@ -6,7 +6,13 @@
     """ The form that is displayed to user.
     """
 
-    topics_interested = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple, choices=TOPICS_CHOICES)       
+    topics_interested = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple, choices=TOPICS_CHOICES, required=False)
     class Meta:
         model = Registrant
 
+    def clean_topics_interested(self):
+        """ Join the choices using PIPE character and store them.
+        """
+
+        topics = self.cleaned_data['topics_interested']
+        return "|".join(topics)