使用cakephp创建optgroup

我是cakephp的新手，在这方面我有一些困难：

从以下sql查询开始：

         select service_group.name as service_group_name, service_group.id as service_group_id, campaign.name as campaign_name, campaign.id as campaign_id
      from group_service
      join group_service_campaign on group.service.id = group_service_campaign.group_service_id
      join campaign on group_service_campaign.campaign_id = campaign.id
      where campaign.active = 'Y'
      and campaign.id in ($in)
      and campaign.company_id = ${_SESSION['companyId']}
      order by group_service.name, campaign.name

我在控制器中将其转换为：

$var_campaign = $this->loadModel('Service_Group');
$var_campaign = $this->Group_Service->find('list', ['keyfield' => 'campaign_id', 'valueField' => 'campaign_name', 'groupField' => 'service_group_name'])
            ->join(['table' => 'service_group_campaign',
                'type' => 'inner',
                'conditions' => 'Service_Group.id = service_group_campaign.service_group_id'
            ])
            ->join(['table' => 'campaign',
        'type' => 'inner',
        'conditions' => 'service_group_campaign.campaign_id = campaign.id'
    ]);
    $var_campaign->where(['campaign.active' => 'Y']);
    $var_campaign->order(['grou_service.name,campaign.name']);

我的难点是如何使用它创建带有optgroup的select表单元素。 我一直在寻找类似的例子和问题，但我所做的一切都不起作用

我的看法是：

echo $this->Form->create();
echo $this->Form->input('id', array('label' => 'Services :', 'type' => 'select', 'empty'=> '-- Select --', 'options' => $var_campaign));
echo $this->Form->select("field", $var_campanha);

echo $this->Form->end();

当我在查询语句中使用find（'list'…）时，我会得到一个空白的响应，如果我使用find（'all'…），我会得到一个不完整的响应，因为所有的活动名称都不会响应，只有带有id的服务组名称

My optgroup显示纯文本，如：

{“id”：-1，“名称”：“现行提案”，“国防部”：“W”，“公司id”：10}

等等

我错在哪里

提前谢谢