请教laravel后端返回的数据格式不对，是漏了什么吗？

laravel后端返回的数据格式不对，是漏了什么吗？

控制器代码是这样的

 $products=Products::get();
            foreach($products as $key =>$json) {
               $data[]=[
                 'ID' =>   $json->id,
                'username'=>$json->name,
                'city'=>     $json->city,
                "birth"=>     $json->birth,
                    ];
                    }
 return  $res = ['code'=>0,'msg'=>'导出成功','data'=>$data];

目前返回的是这样：

"data": 
   0: { 
        "id": "20190510121452124560",
        "username": "user001",
        "city": "城市-9",
        "birth": "2018-12-13",
    }
   1:{
        "id": "20190510121452124560",
        "username": "user001",
        "city": "城市-9",
        "birth": "2018-12-13",
    }

需要的格式是这样：

"data": 
   [ {
        "id": "20190510121452124560",
        "username": "user001",
        "city": "城市-9",
        "birth": "2018-12-13",
    },{
        "id": "20190510121452124560",
        "username": "user001",
        "city": "城市-9",
        "birth": "2018-12-13",
    }]