jackson为什么我需要在子类上使用JsonTypeName注释 [英] jackson why do I need JsonTypeName annotation on subclasses

问题描述

此链接

我正在尝试理解为什么我（可能）需要 @JsonTypeName 关于子类（例如所有'互联网; sujests to put ）如果它没有它？

I'm trying to understand why do I (may) need @JsonTypeName on subclasses (like all 'internet; sujests to put) if it works without it ?

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "aType")
@JsonSubTypes(Array(
  new Type(value = classOf[ModelA], name = "ModelA"),
  new Type(value = classOf[ModelB], name = "ModelB")
))
class BaseModel(val modelName:String)

//@JsonTypeName("SomeModel")  // Commented. Do I need this?
class ModelA(val a:String, val b:String, val c:String, commonData:String)  extends BaseModel(commonData) {
  def this() = this("default", "default", "default" ,"default")
}
//@JsonTypeName("SomeModel") // Commented. Do I need this?
class ModelB(val a:String, val b:String, val c:String, commonData:String)  extends BaseModel(commonData) {
  def this() = this("default", "default", "default" ,"default")
}

推荐答案

你不需要它们。

文档 @JsonSubTypes.Type 解释

子类型的定义以及可选名称。如果缺少name，将检查类型的类是否为JsonTypeName注释;如果它也缺失或为空，则默认名称将由类型id机制构造。默认名称通常基于班级名称。

Definition of a subtype, along with optional name. If name is missing, class of the type will be checked for JsonTypeName annotation; and if that is also missing or empty, a default name will be constructed by type id mechanism. Default name is usually based on class name.

你应该有

@JsonSubTypes(Array(
  new Type(value = classOf[ModelA], name = "ModelA")

... 

class ModelA

或

@JsonSubTypes(Array(
  new Type(value = classOf[ModelA])

... 

@JsonTypeName("ModelA")
class ModelA

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