changvvb / jackson-module-caseclass

Add-on module for Jackson to support Scala case class

Version Matrix

jackson-module-caseclass

Scala CI

Features

  • If one field present in json, just deserialize it.
  • If one field not present in json, but the case class has default value, deserialize it as the case class default value.
  • If one field not present in json, and the case class doesn't has default value, deserialize it as a zero value.
  • Use scala reflect instead of java reflect to constract JavaType, so that jackson-module-caseclass can extract type parameter correctly https://github.com/FasterXML/jackson-module-scala/issues/62.

Zero value

For some scala type, if jackson-module-caseclass doesn't know what a field value should be set, it will be deserialized as a zero value so that we can avoid NullPointerException at most case.

  • Number(Int, Long, Char ...): 0
  • Boolean: false
  • Option: None
  • collection.Map: Map.empty(you should set it as default value in case class definition)
  • Iterable: Nil(same as above)

Dependency

sbt

libraryDependencies += "com.github.changvvb" %% "jackson-module-caseclass" % "1.1.1"

Usage

1. Use @CaseClassDeserialize

import com.fasterxml.jackson.module.caseclass.annotation.CaseClassDeserialize
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.annotation.JsonDeserialize
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper
import com.fasterxml.jackson.module.caseclass.mapper.CaseClassObjectMapper

@CaseClassDeserialize()
case class TestCaseClass(
  intValue:Int,
  stringValue:String,
  seqValue:Seq[_],
  optionValue:Option[_] = None)

val mapper = new ObjectMapper with ScalaObjectMapper with CaseClassObjectMapper

val json =
  """
    |{
    | "intValue": 3,
    | "stringValue": "some strings"
    |}
  """.stripMargin


mapper.readValue[TestCaseClass](json)

2. Use @JsonDeserialize

import com.fasterxml.jackson.module.caseclass.deser.CaseClassDeserializer
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.annotation.JsonDeserialize
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper
import com.fasterxml.jackson.module.caseclass.mapper.CaseClassObjectMapper

class MyDeserializer extends CaseClassDeserializer[TestCaseClass]

@JsonDeserialize(using = classOf[MyDeserializer])
case class TestCaseClass(
  intValue:Int,
  stringValue:String,
  seqValue:Seq[_],
  optionValue:Option[_] = None)
  
val mapper = new ObjectMapper with ScalaObjectMapper with CaseClassObjectMapper
  
val json =
  """
    |{
    | "intValue": 3,
    | "stringValue": "some strings"
    |}
  """.stripMargin


mapper.readValue[TestCaseClass](json)

3. Use registerCaseClassDeserializer()

import com.fasterxml.jackson.module.caseclass.deser.CaseClassDeserializer
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper
import com.fasterxml.jackson.module.caseclass.mapper.CaseClassObjectMapper

case class TestCaseClass(
  intValue:Int,
  stringValue:String,
  seqValue:Seq[_],
  optionValue:Option[_] = None)
  
val mapper = new ObjectMapper with ScalaObjectMapper with CaseClassObjectMapper
mapper.registerCaseClassDeserializer[TestCaseClass]()
  
val json =
  """
    |{
    | "intValue": 3,
    | "stringValue": "some strings"
    |}
  """.stripMargin


mapper.readValue[TestCaseClass](json)

4. Enable all case class

import com.fasterxml.jackson.module.caseclass.deser.CaseClassDeserializer
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper
import com.fasterxml.jackson.module.caseclass.mapper.CaseClassObjectMapper

case class TestCaseClass(
  intValue:Int,
  stringValue:String,
  seqValue:Seq[_],
  optionValue:Option[_] = None)
  
val mapper = new ObjectMapper with ScalaObjectMapper with CaseClassObjectMapper
mapper.setAllCaseClassEnabled(true)
val json =
  """
    |{
    | "intValue": 3,
    | "stringValue": "some strings"
    |}
  """.stripMargin

mapper.readValue[TestCaseClass](json)