[英]Play Framework 2.2.2 Scala JSON reads with undefined/null elements causing NoSuchElementException
Given the following JSON array: 给定以下JSON数组:
{
"success": true,
"data": [
{
"id": 600,
"stage_id": 15,
"title": "test deal",
"value": 0,
"currency": "EUR",
"rotten_time": "2014-03-18 17:45:51",
},
{
"id": 601,
"stage_id": 15,
"title": "test deal2 deal",
"value": 0,
"currency": "EUR",
"rotten_time": "2014-03-24 14:11:00"
},
{
"id": 602,
"stage_id": 15,
"title": "test deal2 deal",
"value": 0,
"currency": "EUR",
"rotten_time": null
}
],
"additional_data": {
"pagination": {
"start": 0,
"limit": 100,
"more_items_in_collection": false
}
}
}
Using the reads method to instanciate objects like below 使用reads方法实例化如下所示的对象
case class Deal(id: Long, stage_id: Long, status: String, rotten_time: Date)
implicit val dealReader = Json.reads[Deal]
val futureJson: Future[List[Deal]] = futureResponse.map(
response => (response.json \ "data").validate[List[Deal]].get
)
I get a NoSuchElementsException when an element's value is null (like for rotten_time) 当元素的值为null时,我会收到NoSuchElementsException(例如rotten_time)
I would like to get something like this 我想得到这样的东西
> println(deals.toString)
> Deal(601,15,open,Mon Mar 18 17:45:51 CET 2014)
> Deal(602,15,open,Mon Mar 18 14:11:00 CET 2014)
> Deal(603,15,open,null)
Is there a way to ensure object instanciation even if a field value is NULL? 即使字段值为NULL,有没有办法确保对象实例化? I see no reason why every existing field has to be assigned a value to.
我认为没有理由为每个现有字段都分配一个值。
I found related questions here and here but they did not help me to solve my problem. 我在这里和这里发现了相关问题,但是它们并没有帮助我解决问题。
I found the answer myself. 我自己找到了答案。 I am new to Scala so it wasn't obvious for me.
我是Scala的新手,所以对我来说并不明显。 Changing the field type to Option[Date] solved the problem.
将字段类型更改为Option [Date]解决了该问题。
case class Deal(id: Long, stage_id: Long, status: String, rotten_time: Option[Date])
So the result is 所以结果是
> println(deals.toString)
> Deal(601,15,open,Some(Mon Mar 18 17:45:51 CET 2014))
> Deal(602,15,open,Some(Mon Mar 18 14:11:00 CET 2014))
> Deal(603,15,open,None)
This is a little bit unexpected as Option[] is said to be a way around NullPointerException
s but not NoSuchElementException
s. 这有点出乎意料,因为据说Option []是解决
NullPointerException
而不是NoSuchElementException
的一种方法。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.