The 'changes sidebar' should allow the user to choose a date and reload itself without reloading the whole page.
Ok, so you need AJAX for this part. For more complex projects you can use django-rest-framework or tastypie but for this I reccomend to do an AJAX function that gets a date as parameter and return a rendered template. See this thread and this one too
To include the sidebar, I'll just create a separate template for it and include {% include 'changes_sidebar.html' %} you also need to include the javascript to do the ajax requests.