jackson.md

kTest :: Integration :: Jackson

Download

Gradle

'run.smt.ktest:ktest-jackson'

Maven

<dependency>
    <groupId>run.smt.ktest</groupId>
    <artifactId>ktest-jackson</artifactId>
</dependency>

Description

Provides some DSL for Jackson JSON library

There are 2 ways to use this DSL: either by explicitly specifying what mapper to use or just using globally configured mapper. In samples below (until explicitly specified) used second method is used which also works with explicit specification of mapper.

Default ObjectMapper

import run.smt.ktest.json.*

fun usage1() {
    println(mapper.writeValueAsString(mapOf("hello" to "world")))
}

Extension functions

import run.smt.ktest.json.*

class MyPojo(/* POJO fields */)

fun usage2() {
    val myPojo = mapper.readValue<MyPojo>(stringOrByteArrayOrStreamOrUrlOrFileOrReader)
}

TypeDSL

package typedsl

import run.smt.ktest.json.*

class MyGenericPojo<T> { /*some body*/ }

fun usage3() {
    fun usage(mySource: String) {
        val myPojo: Map<String, Set<MyGenericPojo<List<String>>>> = mapper.readValue(mySource, type {
            // sadly arbitrary generics still need type specialization...
            map(simple(String::class), set(generic<MyGenericPojo<List<String>>>(MyGenericPojo::class, list<String>())))
        })
    }
}

Serialization

import run.smt.ktest.json.*

fun usage4(myPojo: MyPojo) {
    val jsonAsBytes = myPojo.serialize()
    val myPrettyJsonAsString = myPojo.dump()
}

Deserializtion

package deserialization

import run.smt.ktest.json.*
import com.fasterxml.jackson.databind.JsonNode
import com.jayway.jsonpath.* // if you have json-path as your dependency

class SomePojo { /* some body */ }
class SomeGenericPojo<T> { /* some body */ }

fun usage5(myData: String) {
    val deserialized1 = myData.deserialize<SomePojo>()
    val deserialized2 = myData deserialize SomePojo::class
    val deserialized3 = myData deserialize { generic<SomeGenericPojo<List<String>>>(SomeGenericPojo::class, list<String>()) }
    val deserializedAsJsonNode = myData deserialize JsonNode::class
    
    // if you added json-path as dependency to your project
    val deserializedAsJsonPath = myData deserialize DocumentContext::class
}

Mapping

package mapping

import run.smt.ktest.json.*
import com.fasterxml.jackson.databind.JsonNode
import com.jayway.jsonpath.* // if you have json-path as your dependency

class SomePojo { /* some body */ }
class SomeGenericPojo<T> { /* some body */ }

fun usage6(myData: JsonNode) {
    val mapped1 = myData.mapTo<SomePojo>()
    val mapped2 = myData mapTo SomePojo::class
    val mapped3 = myData mapTo { generic<SomeGenericPojo<List<String>>>(SomeGenericPojo::class, list<String>()) }
    val mappedToJsonNode = myData mapTo JsonNode::class
    
    // if you added json-path as dependency to your project
    val mappedToJsonPath = myData mapTo DocumentContext::class
}

Using custom mapper

import com.fasterxml.jackson.databind.ObjectMapper
import run.smt.ktest.json.with

fun usage7(myMapper: ObjectMapper) {
    with(myMapper) {
        "{}" deserialize { map<String, String>() }
    }
}

Configuring global mapper

1. Implement run.smt.ktest.json.JsonConfigurer
2. Register it in configuration at path json.configurers
3. PROFIT

import run.smt.ktest.json.JsonConfigurer
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.DeserializationFeature

object MyConfigurer : JsonConfigurer {
    override fun invoke(mapper: ObjectMapper): ObjectMapper {
        return mapper.disable(DeserializationFeature.FAIL_ON_IGNORED_PROPERTIES)
    }
}

json.configurers = ["MyConfigurer"]