How to use jackson to deserialize to Kotlin collections

Question

Sample code what I want:

data class D(val a: String, val b: Int) val jsonStr = """[{"a": "value1", "b": 1}, {"a": "value2", "b":"2}]""" // what I need val listOfD: List<D> = jacksonObjectMapper().whatMethodAndParameter? 

Answer 1

With Jackson Kotlin Module current versions, if you import the full module package or the specific extension function you'll have all extension methods available. Such as:

import com.fasterxml.jackson.module.kotlin.*   val JSON = jacksonObjectMapper()  // keep around and re-use val myList: List<String> = JSON.readValue("""["a","b","c"]""") 

Therefore the Jackson Module for Kotlin will infer the the correct type and you do not need a TypeReference instance.

so your case (slightly renamed and fixed the data class, and JSON):

import com.fasterxml.jackson.module.kotlin.readValue  data class MyData(val a: String, val b: Int) val JSON = jacksonObjectMapper()    val jsonStr = """[{"a": "value1", "b": 1}, {"a": "value2", "b": 2}]""" val myList: List<MyData> = JSON.readValue(jsonStr) 

You can also use the form:

val myList = JSON.readValue<List<MyData>>(jsonStr) 

Without the import you will have an error because the extension function is not found.