app/views/admin/dashboard_messages/edit.html.erb
<h1>Dashboard Message for <%= @messageable.name %></h1>
<%= simple_form_for(@dashboard_message, url: [:admin, @messageable, :dashboard_message], method: :put) do |f| %>
<%= redirect_back_tag params %>
<%= f.input :message %>
<%= link_to 'Back', redirect_back_url(params), class: 'btn' %>
<%= f.submit 'Save', class: "btn float-right ml-2" %>
<% unless @dashboard_message.new_record? %>
<%= link_to 'Delete', polymorphic_url([:admin, @messageable, :dashboard_message], redirect_back_params(params)), method: :delete, data: {confirm: 'Are you sure?'}, class: 'btn float-right' %>
<% end %>
<% end %>