RocZhang9673/gsonkeepdefault

gsonkeepdefault

This is a pure kotlin library used together with Gson in the scenarios of decoding JSON data with a data class in Kotlin.

Background

If we have code like this:

data class AValue(val a: String = "keep me")
val a1 = Gson.fromJson("""{"a":null}""", AValue::class.java)
print(a1.a) // null

This happens often during developing, since Kotlin can do no assurance on JVM running time.

However, what we need is pretty simple: we want our codes run as they seem like. So I write this gsonkeepdefault library to help you keep the default values of data class in development.

How to use

Dependency (gradle)

repositories {
  maven { url "https://jitpack.io" }
}

apply plugin 'kotlin-kapt'

dependencies {
  implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
  implementation "com.github.zijing07.gsonkeepdefault:core:1.1"
  kapt "com.github.zijing07.gsonkeepdefault:processor:1.1"
}

Dependency (kotlin dsl build script)

plugins {
  kotlin("jvm")
  kotlin("kapt")
}

repositories {
  maven(url = "https://jitpack.io")
}

dependencies {
  implementation(kotlin("stdlib"))
  implementation("com.github.zijing07.gsonkeepdefault:core:1.1")
  kapt("com.github.zijing07.gsonkeepdefault:processor:1.1")
}

Kotlin

@KeepDefault
data class AValue(val a: String = "keep me")
val a1 = KGson.fromJson<AValue>("""{"a":null}""")
print(a1.a) // "keep me"

Note that you need to use KGson here instead of Gson.

Related Libraries

Moshi Innovated me on the idea
Kotlin Metadata Really excellent work, does help to extract the default modifier info from a data class
Kotlin Poet A really good poet to be a parter of annotation processors

RocZhang9673 / gsonkeepdefault