json - 将 Json 数组反序列化为 Scala 对象

Question

我在尝试将 JSON 数组反序列化为 Scala 对象时遇到了主要问题

      [{"name":"Cool","city":"College Park","address":"806","id":1},{"name":"Mars ","city":"Durham","address":"12","id":2},{"name":"Something","city":"Raleigh 
","address":"","id":3},{"name":"test","city":"","address":"","id":5}]

我尝试过 gson、jerkson(jackson scala 包装器)、sjson、flexjson。他们都没有工作。我这里有一份客户名单。列出[客户]。

这是我最接近的:

val array = new JsonParser().parse( customers ).getAsJsonArray()

这给了我 4 个数组。不过，它显然没有给我一个客户对象。我试过 jack 森。

val array = parse[List[Customer]](customers)

但我明白了。

GenericSignatureFormatError occured : null

我只是想找到一种简单的方法，就像我在 Java 中所做的那样。

这是我的 Scala 课。

    case class Customer(
    id : Pk[ Int ],
    name : String,
    address : Option[ String ],
    city : Option[ String ],
    state : Option[ String ],
    user_id : Int )

    object Customer extends Magic[ Customer ]( Option( "Customer" ) ) { 

    def apply( name : String, address : String, city : String, state : String, user_id : Int ) = {
        new Customer( NotAssigned, name, Some( address ), Some( city ), Some( state ), user_id )
    }

    def delete( id : Int ) = {
        SQL( "DELETE from Customer where id = {id}" ).onParams( id ).executeUpdate()
    }

}

谢谢你的帮助。

Answer 1

使用 gson，您可以编写自己的 json 阅读器:

case class Customer(id: Int, name: String, address: Option[String], 
  city: Option[String], state: Option[String], user_id: Int)

object CustomerJsonReader {

   def read(in: Reader) = readCustomers(new JsonReader(in))

   def readCustomers(reader: JsonReader) = {
     val customers = new ListBuffer[Customer]
     reader.beginArray()
     while (reader.hasNext()) {
       customers += readCustomer(reader)
     }
     reader.endArray()
     customers toList
   }

   def readCustomer(reader: JsonReader): Customer = {
     var id = 0
     var customerName = ""
     var address: Option[String] = None
     var city: Option[String] = None
     var state: Option[String] = None
     var userId = 0

     reader.beginObject()
     while (reader.hasNext()) {
       val name = reader.nextName()
       name match {
         case "id" => id = reader.nextInt()
         case "address" => address = Some(reader.nextString())
         case "state" => state = Some(reader.nextString())
         case "user_id" => userId = reader.nextInt()
         case "name" => customerName = reader.nextString()
         case "city" => city = Some(reader.nextString())
         case _ => reader.skipValue()
       }
     }
     reader.endObject()
     Customer(id, customerName, address, city, state, userId)
   }

}

val json = 
  """
  [{"name":"Cool","city":"College Park","address":"806","id":1},
  {"name":"Mars ","city":"Durham","address":"12","id":2},
  {"name":"Something","city":"Raleigh  ","address":"","id":3},
  {"name":"test","city":"","address":"","id":5}] 
  """

val customers: List[Customer] = 
  CustomerJsonReader.read(new StringReader(json))