phpcms调用getJSON无法返回json数据的解决方法

public function public_mobile_getjson_ids() {//publc是后来加上去的
$modelid = intval($_GET['modelid']);
$id = intval($_GET['id']);
$this->db->set_model($modelid);
$tablename = $this->db->table_name;
$this->db->table_name = $tablename.'_data';
$r = $this->db->get_one(array('id'=>$id),'mobile_type');

if($r['mobile_type']) {
$relation = str_replace('|', ',', $r['mobile_type']);
$relation = trim($relation,',');
$where = "id IN($relation)";
$infos = array();
$this->mobile_db = pc_base::load_model ( 'mobile_type_model' );
$datas = $this->mobile_db->select($where,'id,type_name');
//$this->db->table_name = $tablename;
//$datas = $this->db->select($where,'id,title');
foreach($datas as $_v) {
$_v['sid'] = 'v'.$_v['id'];
if(strtolower(CHARSET)=='gbk') $_v['type_name'] = iconv('gbk', 'utf-8', $_v['type_name']);
$infos[] = $_v;
}
echo json_encode($infos);
}
}

js部分的getJSON是这样写的：

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