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https://github.com/kittinunf/Forge

Functional style JSON parsing in Kotlin
https://github.com/kittinunf/Forge

functional functional-programming json kotlin parser

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Functional style JSON parsing in Kotlin

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# Forge

[![Kotlin](https://img.shields.io/badge/Kotlin-1.4.0-blue.svg)](http://kotlinlang.org)
[![jcenter](https://api.bintray.com/packages/kittinunf/maven/Forge/images/download.svg)](https://bintray.com/kittinunf/maven/Forge/_latestVersion)
[![MavenCentral](https://maven-badges.herokuapp.com/maven-central/com.github.kittinunf.forge/forge/badge.svg)](https://search.maven.org/search?q=g:com.github.kittinunf.forge)
[![Build Status](https://travis-ci.org/kittinunf/Forge.svg?branch=master)](https://travis-ci.org/kittinunf/Forge)
[![](https://jitpack.io/v/kittinunf/forge.svg)](https://jitpack.io/#kittinunf/forge/)
[![Codecov](https://codecov.io/github/kittinunf/Forge/coverage.svg?branch=master)](https://codecov.io/gh/kittinunf/Forge)

Forge is a JSON library that helps you map your Kotlin class from a JSON and vice versa in a functional way. Forge is highly inspired by [Aeson](https://hackage.haskell.org/package/aeson), JSON parsing library in Haskell.

## Ideology

Have you ever wonder that how other JSON libraries out there work? Magic under the hood? or a complex annnotation processing? If that is something that you don't want, with Forge, we don't do any of those.

Forge aims to provide a full control over how to parse JSON into a Kotlin class, no more magic, no more annotation.

## Installation

### Gradle

```
repositories {
jcenter() //or mavenCentral()
}

dependencies {
compile 'com.github.kittinunf.forge:forge:'
}
```

### Usage (tl;dr:)

Given you have JSON as such

``` Json
{
"id": 1,
"name": "Clementina DuBuque",
"age": 46,
"email": "[email protected]",
"phone": {
"name": "My Phone",
"model": "Pixel 3XL"
},
"friends": [
{
"id": 11,
"name": "Ervin Howell",
"age": 32,
"email": "[email protected]",
"phone": {
"name": "My iPhone",
"model": "iPhone X"
},
"friends": []
}
],
"dogs": [
{
"name": "Lucy",
"breed": "Dachshund",
"is_male": false
}
]
}
```

You can write your Kotlin class definition as such

``` Kotlin
data class User(val id: Int,
val name: String,
val age: Int,
val email: String?,
val phone: Phone,
val friends: List,
val dogs: List?)

data class Phone(val name: String, val model: String)
data class Dog(val name: String, val breed: String, val male: Boolean)

fun userDeserializer(json: JSON) =
::User.create.
map(json at "id").
apply(json at "name").
apply(json at "age").
apply(json maybeAt "email").
apply(json.at("phone", phoneDeserializer)), // phoneDeserializer is a lambda, use it directly
apply(json.list("friends", ::userDeserializer)). //userDeserializer is a function, use :: as a function reference
apply(json.maybeList("dogs", dogDeserializer))

val phoneDeserializer = { json: JSON ->
::Phone.create.
map(json at "name").
apply(json at "model")
}

val dogDeserializer = { json: JSON ->
::Dog.create.
map(json at "name").
apply(json at "breed").
apply(json at "is_male")
}

```

Viola!, then, you can deserialize your JSON like

``` Kotlin

//jsonContent is when you receive data as a JSON
val result = Forge.modelFromJson(jsonContent, ::userDeserializer)

when (result) {
DeserializedResult.Success -> {
val user = result.value
//success, do something with user
}

DeserializedResult.Failure -> {
val error = result.error
//failure, do something with error
}
}

```

You can also serialize you Kotlin class definition as JSON such:

```kotlin
fun userSerializer(user: User) = JSON.Object(mapOf(
"id" to user.id.toJson(),
"name" to user.name.toJson(),
"age" to user.age.toJson(),
"email" to user.email.maybeJson(),
"friends" to user.friends.toJson(::userSerializer),
"dogs" to user.dogs.maybeJson(::dogSerializer)
))

fun dogSerializer(dog: Dog) = JSON.Object(mapOf(
"name" to dog.name.toJson(),
"breed" to dog.breed.toJson(),
"male" to dog.male.toJson()
))

val json = Forge.jsonFromModel(model, ::userSerializer)

json.asString()
/* ==>
{
"id": 1,
"name": "Clementina DuBuque",
"age": 46,
"email": "[email protected]",
"friends": [
{
"id": 11,
"name": "Ervin Howell",
"age": 32,
"email": "[email protected]",
"friends": []
}
],
"dogs": [
{
"name": "Lucy",
"breed": "Dachshund",
"is_male": false
}
]
}
*/
```

## Credits

Forge is brought to you by [contributors](https://github.com/kittinunf/Fuel/graphs/contributors).

## Licenses

Forge is released under the [MIT](https://opensource.org/licenses/MIT) license.