canvas-lms/app/messages/assignment_due_date_changed.facebook.erb

<% define_content :link do %>
  <%= HostUrl.protocol %>://<%= HostUrl.context_host(asset.context) %>/<%= asset.context.class.to_s.downcase.pluralize %>/<%= asset.context_id %>/assignments/<%= asset.id %>
<% end %>

<%= t('assignment_due_date_changed_sentence', 'The due date for the assignment *%{assignment_name}* for %{course_name}, has changed to:', :assignment_name => asset.title, :course_name => asset.context.name, :wrapper => "<b><a href=\"#{content :link}\">\\1</a></b>") %>

<b>
  <% if asset.due_at %>
    <%= datetime_string(force_zone(asset.due_at)) %>
  <% else %>
    <%= t('no_due_date', 'No Due Date') %>
  <% end %>
</b>