我试图使用Lift框架反序列化JSON文本,并且它没有出现它们支持Seq特征(尽管List支持)。作为一个例子...Lift Framework无法反序列化JSON数据
代表雇员(含姓和名)一些JSON数据...
{"employees":[{"fname":"Bob","lname":"Hope"},{"fname":"Bob","lname":"Smith"}]}
这里的员工域的对象:
case class Employee(fname: String, lname: String) { }
case class Employees(employees: Seq[Employee]) { }
这是我的JSON反序列化代码...
class EmployeeTest {
@Test def test() {
val jsonText: String = ....
val e = deserialize(jsonText)
}
def deserialize(in: String): Employees = {
implicit val formats = net.liftweb.json.DefaultFormats
net.liftweb.json.Serialization.read[Employees](in)
}
}
如果我更改Employees域对象以使用List而不是Seq,th它的工作原理。但如果可以的话,我真的很想使用Seq。
下面是我运行上面的代码(使用Seq)时看到的异常:有什么我可以做到的吗?谢谢你的帮助!
net.liftweb.json.MappingException: unknown error
at net.liftweb.json.Extraction$.extract(Extraction.scala:43)
at net.liftweb.json.JsonAST$JValue.extract(JsonAST.scala:288)
at net.liftweb.json.Serialization$.read(Serialization.scala:50)
at EmployeeTest.deserialize(EmployeeTest.scala:20)
at EmployeeTest.test(EmployeeTest.scala:13)
Caused by: java.lang.UnsupportedOperationException: tail of empty list
at scala.collection.immutable.Nil$.tail(List.scala:388)
at scala.collection.immutable.Nil$.tail(List.scala:383)
at net.liftweb.json.Meta$Constructor.bestMatching(Meta.scala:60)
at net.liftweb.json.Extraction$.findBestConstructor$1(Extraction.scala:187)
at net.liftweb.json.Extraction$.instantiate$1(Extraction.scala:192)
at net.liftweb.json.Extraction$.newInstance$1(Extraction.scala:222)
at net.liftweb.json.Extraction$.build$1(Extraction.scala:240)
at net.liftweb.json.Extraction$.mkValue$1(Extraction.scala:269)
at net.liftweb.json.Extraction$.build$1(Extraction.scala:242)
at net.liftweb.json.Extraction$$anonfun$4.apply(Extraction.scala:194)
at net.liftweb.json.Extraction$$anonfun$4.apply(Extraction.scala:194)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:206)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:206)
at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:61)
at scala.collection.immutable.List.foreach(List.scala:45)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:206)
at scala.collection.immutable.List.map(List.scala:45)
at net.liftweb.json.Extraction$.instantiate$1(Extraction.scala:194)
at net.liftweb.json.Extraction$.newInstance$1(Extraction.scala:222)
at net.liftweb.json.Extraction$.build$1(Extraction.scala:240)
at net.liftweb.json.Extraction$.extract(Extraction.scala:284)
at net.liftweb.json.Extraction$.extract0(Extraction.scala:172)
at net.liftweb.json.Extraction$.extract(Extraction.scala:40)
... 33 more
我就遇到了这个问题也很高兴你问这个问题。如果lift-json打印出更多信息错误信息,那将会很好。 – 2011-07-26 00:19:12