<%= simple_form_for(@message) do |f| %>
  <%= f.error_notification %>

  <div class="inputs">
    <%= f.input :receiver_id %>
    <%= f.input :subject %>
    <%= f.input :message_text, as: :text %>
  </div>

  <div class="actions">
    <%= f.button :submit, class: "btn btn-primary btn-small" %>
  </div>

<% end %>