randomize: fix off-by-1 issue with staff controls

* Require staff in randomize xmodule's handle_ajax!!!
* Use .val() instead of .text() in rand_jump JS
* Disable all alert() calls when using 'next' or 'jump' controls

common/lib/xmodule/xmodule/randomize_module.py

@@ -48,7 +48,6 @@ class RandomizeModule(RandomizeFields, XModule):
         # NOTE: calling self.get_children() creates a circular reference --
         # it calls get_child_descriptors() internally, but that doesn't work
         # until we've picked a choice
-        # import pudb; pudb.set_trace()
         xml_attrs = self.descriptor.xml_attributes or []
         use_randrange = 'use_randrange' in xml_attrs
         # TODO: use this attr to toggle storing history and never showing the
@@ -140,16 +139,18 @@ class RandomizeModule(RandomizeFields, XModule):
         return child_html
 
     def handle_ajax(self, dispatch, data):
-        choices = self.get_choices().keys()
-        index = self.get_choice_index(choices=choices)
-        if dispatch == 'next':
-            self.choice = choices[index + 1]
-        elif dispatch == 'jump':
-            log.debug('jump, data=%s' % data)
-            self.choice = choices[int(data['choice'])]
-        #num_choices = len(choices)
-        #if self.choice >= num_choices:
-            #self.choice = 0
+        if self.runtime.user_is_staff:
+            choices = self.get_choices().keys()
+            index = self.get_choice_index(choices=choices)
+            try:
+                if dispatch == 'next':
+                    self.choice = choices[index + 1]
+                elif dispatch == 'jump':
+                    log.debug('jump, data=%s' % data)
+                    self.choice = choices[int(data['choice'])]
+            except (IndexError, ValueError):
+                # log the error in this case and return the current choice
+                log.exception("error in randomize next/jump (IGNORED):")
         result = {'ret': "choice=%s" % self.choice}
         return json.dumps(result)
 

lms/templates/randomize_control.html

 % if is_staff:
 <div id="randomize_${element_id}_control">
     <p>
-    <input id="randomize_next" type="button" value="This is randomized module ${choice} of ${num_choices}: Go to next"/>
+    <input id="randomize_next" type="button" value="This is randomized module ${choice + 1} of ${num_choices}: Go to next"/>
     or jump to:
     <select id="randomize_jump">
         % for kchoice in range(num_choices):
 	    <% selected = "selected" if kchoice==choice else "" %>
-	    <option value="${kchoice}" ${selected}>${kchoice}</option>
+	    <option value="${kchoice}" ${selected}>${kchoice + 1}</option>
         % endfor
     </select>
     </p>
@@ -17,18 +17,18 @@
 do_next = function(){
     $.get( "${ajax_url}/next", function( data ) {
       $( "#randomize_next" ).html( data );
-      alert( "next successful" );
+      // alert( "next successful" );
       location.reload();
     });
 }
 $('#randomize_next').click(do_next);
 
 rand_jump = function(){
-    var choice = $('#randomize_jump option:selected').text();
+    var choice = $('#randomize_jump option:selected').val();
     $.post( "${ajax_url}/jump", { 'choice': choice},
       function( data ) {
         $( "#randomize_next" ).html( data );
-        alert( "jump to " + choice + " successful" );
+        // alert( "jump to " + choice + " successful" );
         location.reload();
       });
 }