does not show the ODS button if the visualization is not valid (fixes #21457)

bijoe/templates/bijoe/cube.html

@@ -26,7 +26,9 @@
 {% block content %}
   <form class="cube-form" method="post" action=".">
     {% csrf_token %}
-    <input type="submit" value="ODS" name="ods" id="ods"/>
+    {% if visualization %}
+       <input type="submit" value="ODS" name="ods" id="ods"/>
+    {% endif %}
     <h3>Représentation</h3>
     {% include "bijoe/field.html" with field=form.representation %}
     <h3>Répétition</h3>

bijoe/visualization/views.py

@@ -83,6 +83,8 @@ class CubeMixin(object):
 
 class ODSMixin(object):
     def ods(self, visualization):
+        if not self.visualization:
+            raise Http404
         response = HttpResponse(content_type='application/vnd.oasis.opendocument.spreadsheet')
         response['Content-Disposition'] = 'attachment; filename=%s.ods' % self.cube.name
         workbook = visualization.ods()