如何迭代 org.json4s.JsonAST.JValue，它是一个 JSON 对象数组，以分别处理 Scala 中的每个对象？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/34898951/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to iterate org.json4s.JsonAST.JValue which is an array of JSON objects to separately work on each object in Scala?
提问by GKVM
I have a sample array:
我有一个示例数组：
[{
"abc":"1",
"de":"1"
},
{
"fgh":"2",
"ij":"4"
}]
which is a org.json4s.JsonAST.JValue.
这是一个 org.json4s.JsonAST.JValue。
How is it possible to iterate over each object inside the array, to operate on each object separately?
如何遍历数组内的每个对象，分别对每个对象进行操作？
回答by ixguza
The following is your json.
以下是你的json。
scala> json
res2: org.json4s.JValue = JArray(List(JObject(List((abc,JString(1)), (de,JString(1)))),
JObject(List((fgh,JString(2)), (ij,JString(4))))))
There are several ways.
有几种方法。
use
forsyntaxfor { JArray(objList) <- json JObject(obj) <- objList } { // do something val kvList = for ((key, JString(value)) <- obj) yield (key, value) println("obj : " + kvList.mkString(",")) }convert to
scala.collectionobjectval list = json.values.asInstanceOf[List[Map[String, String]]] //=> list: List[Map[String,String]] = List(Map(abc -> 1, de -> 1), Map(fgh -> 2, ij -> 4))or
implicit val formats = DefaultFormats val list = json.extract[List[Map[String,String]]] //=> list: List[Map[String,String]] = List(Map(abc -> 1, de -> 1), Map(fgh -> 2, ij -> 4))and do something.
for (obj <- list) println("obj : " + obj.toList.mkString(","))
使用
for语法for { JArray(objList) <- json JObject(obj) <- objList } { // do something val kvList = for ((key, JString(value)) <- obj) yield (key, value) println("obj : " + kvList.mkString(",")) }转换为
scala.collection对象val list = json.values.asInstanceOf[List[Map[String, String]]] //=> list: List[Map[String,String]] = List(Map(abc -> 1, de -> 1), Map(fgh -> 2, ij -> 4))或者
implicit val formats = DefaultFormats val list = json.extract[List[Map[String,String]]] //=> list: List[Map[String,String]] = List(Map(abc -> 1, de -> 1), Map(fgh -> 2, ij -> 4))并做某事。
for (obj <- list) println("obj : " + obj.toList.mkString(","))
Both outputs are
两个输出都是
obj : (abc,1),(de,1)
obj : (fgh,2),(ij,4)
The document of json4s is here.
json4s 的文档在这里。
回答by Yuri Schimke
You should be able to either cast to JArray
您应该能够转换为 JArray
val myArray = myVal.asInstanceOf[JArray]
myArray.arr // the array
or preferably use a scala match so you can confirm the type is correct.
或者最好使用 scala 匹配，以便您确认类型正确。
