Checkbox scopes in doorkeeper

I want to allow users to select scopes from a checkbox list. I've setup the form like so:

  <%= f.label :scopes, class: 'col-sm-2 control-label' %>
    <% Doorkeeper.configuration.scopes.each do |scope| %>
      <%= check_box_tag("doorkeeper_application[scopes][#{scope}]", scope, @application.scopes.include?(scope)) %>
      <%= scope %><br>
    <% end %>
  <% end %>

which produces

doorkeeper_application[scopes] is accepted by Oauth::ApplicationsController. While users should be able to select multiple scopes, parameters like doorkeeper_application[scopes][foo] are not accepted.

What's the best practice for passing these params to the controller? Or is there a better practice to achieve checkboxed scopes in Doorkeeper?

According to the OAuth2 specification, multiple scopes should be joined by space characters. So you should get the names of the checked scopes from params, join them with a space " ", and assign that single value as the doorkeeper_application[scopes] value.