app/views/comments/_form.html.erb
<div class="discussion-comment" id='comment-<%= comment.id %>'>
<div class="pic">
<%= link_to participant_path(current_participant) do %>
<%= concept(Image::Cell,current_participant) %>
<% end %>
</div>
<%= form_for [topic, comment], html: { class: 'add-comment', id: 'new_comment' } do |f| %>
<%= f.text_area :comment_markdown, placeholder: "Add a comment...", data: { behavior: "mentions" } %>
<% if comment.persisted? %>
<%= f.hidden_field :participant_id, value: comment.participant.id %>
<% else %>
<%= f.hidden_field :participant_id, value: current_participant.id %>
<% end %>
<%= f.hidden_field :mentions_cache %>
<%= f.submit (f.object.new_record? ? "Add Comment" : "Update Comment"), class: 'btn btn-primary pull-right' %>
<p class='markdown-instructions'>You can use
<a href="https://kramdown.gettalong.org/">kramdown</a> and <b>@mentions</b> in this field.
</p>
<% end %>
</div>