无法在Mongodb中序列化LocalDate

Question

private def writeData(measure: DBCollection, installation: Int, date: String, dates: ListBuffer[LocalDate],
                    values: ListBuffer[BigDecimal], validated: Boolean, overwrite: Boolean) {
  val timeValues: BasicDBList = new BasicDBList
  var i = 0
  while ( i < dates.size )  {
    val obj: BasicDBObject = new BasicDBObject("time", dates(i))
    obj.put("value", values(i).toString())
    timeValues.add(obj)
    i += 1
  }
  if ( debug ) System.out.println("Storedata: " + timeValues.toString) <-- error here

java.lang.runtimeException：json无法序列化类型：在com.mongodb.util.ClassMapBasedObjectSerializer.serializer(ClassMapBasedObjectSerializer.java:77)在com.mongodb.util.ClassMapBasedObjectSerializer.serializer(jsonSerializers.java:317)在）在com.mongodb.util.classmapbasedObjectSerializer.serialize(classmapbasedObjectSerializer.java:79)在com.mongodb.util.json.serialize(json.java:54)在com.mongodb.util.json.serialize(json.java:40)在com.mongodb.util.json.serialize(json.java:40)在位于sun.reflect.n的VemethodAccessorImpl.Invoke0（本机方法）在sun.reflect.delegatingMethodAccessorImpl.invoke(nativeMethodAccessorImpl.java:62)，java.lang.reflect.method.invoke(method.java:43)，com.intellij.rt.execution.application.appmain.main(appmain.java:134)，java.lang.reflect.method.invoke(method.java:483)

我使用的是mongo-java-driver-2.13.0-rc1.jar Scala 2.11.4和java 1.8.0_25

为了完整性。

Answer 1

不幸的是，MongoDB驱动程序使用java.util.date类型，请参见此处的文档

因此，必须首先将LocalDate转换为Date实例，例如：

MongoClient mongoClient = new MongoClient("localhost", 27017);
DB db = mongoClient.getDB("test");
DBCollection coll = db.getCollection("testcol");

LocalDate ld = LocalDate.now();
Instant instant = ld.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant();
Date date = Date.from(instant);

BasicDBObject doc = new BasicDBObject("localdate", date);
coll.insert(doc);

不过，我建议使用Morphia或Jongo之类的东西来包装MongoDB驱动程序，因为您可以注册全局映射器来动态隐式地执行这些转换，这样您就可以在域模型中使用LocalDate等