Created
April 8, 2022 21:55
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Custom Jackson deserializer registered with the mapper
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| package us.aharon.test.json | |
| import com.fasterxml.jackson.annotation.JsonProperty | |
| import com.fasterxml.jackson.core.JsonParser | |
| import com.fasterxml.jackson.databind.{DeserializationContext, JsonDeserializer, JsonNode} | |
| import com.fasterxml.jackson.databind.json.JsonMapper | |
| import com.fasterxml.jackson.databind.module.SimpleModule | |
| import com.fasterxml.jackson.module.scala.DefaultScalaModule | |
| object JacksonRegisteredSerializers extends App { | |
| /** | |
| * Custom Jackson deserializer for BigInt. | |
| * | |
| * Expects [[BigInt]] in JSON as a [[String]]. | |
| * {{{ | |
| * { | |
| * "a_big_int": "123456789123456789" | |
| * } | |
| * }}} | |
| */ | |
| private class BigIntDeserializer extends JsonDeserializer[BigInt] { | |
| override def deserialize(p: JsonParser, ctxt: DeserializationContext): BigInt = { | |
| val node: JsonNode = p.getCodec.readTree(p) | |
| BigInt(node.asText) | |
| } | |
| } | |
| // Define a module for the custom deserializer. | |
| val bigIntModule = new SimpleModule() | |
| .addDeserializer(classOf[BigInt], new BigIntDeserializer()) | |
| val mapper = JsonMapper.builder() | |
| .addModule(DefaultScalaModule) // Register the module with the mapper. | |
| .addModule(bigIntModule) | |
| .build() | |
| /** | |
| * Our example object as a target for deserialization. | |
| */ | |
| case class ExampleObj( | |
| @JsonProperty("a_big_int") | |
| val aBigInt: BigInt | |
| ) | |
| val example = | |
| """ | |
| |{ | |
| | "a_big_int": "123456789123456789" | |
| |} | |
| |""".stripMargin | |
| // Deserialize | |
| val actual = mapper.readValue(example, classOf[ExampleObj]) | |
| val expected = ExampleObj(BigInt("123456789123456789")) | |
| println(s"Deserialized ExampleObj: $actual") | |
| assert(actual == expected) | |
| } |
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