Add twitter_handle tag

pinaxcon/templates/symposion/schedule/presentation_detail.html

@@ -33,7 +33,7 @@
           <p>
             <strong>{{ speaker }}</strong><br />
             {% if speaker.twitter_username %}
-              <a href="https://twitter.com/{{ speaker.twitter_username }}">{{ speaker.twitter_username }}</a><br />
+              <a href="https://twitter.com/{{ speaker.twitter_username }}">{{ speaker.twitter_username|twitter_handle }}</a><br />
             {% endif %}
             {% if speaker.homepage %}
               <a href="{{ speaker.homepage }}">{{ speaker.homepage }}</a>

pinaxcon/templatetags/lca2019_tags.py

@@ -36,4 +36,9 @@ def listlookup(lookup, target):
 @register.filter
 def clean_text(txt):
     # Remove double/triple/+ spaces from `txt` and replace with single space
-    return re.sub(r' {2,}' , ' ', txt)
+    return re.sub(r' {2,}' , ' ', txt)
+
+@register.filter
+def twitter_handle(txt):
+    # Add @ to twitter handle if not present
+    return txt if txt.startswith('@') else '@{}'.format(txt)