Html rails中的多选框和Css

所以我有一个表格：

<%= form_for @role, :html => {:class => 'form-horizontal'} do |f|%>

  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <h3>Create a new role</h3>
      <p class="text-muted">Create a new role below.</p>
    </div>
  </div>

  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-6">
      <%= render :partial => 'form_errors', :object => @user %>
    </div>
  </div>

  <div class="form-group">
    <%= f.label :role, :class => 'col-sm-2 control-label' %>
    <div class="col-sm-6">
      <%= f.text_field :role, :class => 'form-control' %>
    </div>
  </div>

  <div class="form-group">
    <label class="col-sm-2 control-label'">Select permissions for this role</label>
    <div class="col-sm-6">
      <%= f.select(:permissions, options_for_select(Xaaron::Permission.pluck(:permission),
        :selected => @role.permissions), :class => 'form-control') %>
    </div>
  </div>

  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <%= f.submit "Create Role", :class => 'btn btn-primary' %>
    </div>
  </div>
<% end %>

您会注意到，有一个选择框，允许您为角色选择权限，我希望这是一个多选框，允许您为角色选择多个权限，并且具有当前没有的css表单控件类。

试试看

<div class="form-group">
  <label class="col-sm-2 control-label'">Select permissions for this role</label>
  <div class="col-sm-6">
    <%= f.select(:permissions, options_for_select(Xaaron::Permission.pluck(:permission),
        :selected => @role.permissions), {}, {:multiple => true, :class => 'form-control'}) %>
  </div>
</div>

---

第三个参数是选项，第四个是HTML选项；