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docs: add docs for scala 3
scarf005 Dec 27, 2024
f7fc5b0
docs: use tabs
scarf005 Feb 5, 2025
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96 changes: 66 additions & 30 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ The goal of this project is to create the best all-round JSON library for Scala:
In order to use this library, we need to add the following line in our `build.sbt` file:

```scala
libraryDependencies += "dev.zio" %% "zio-json" % "0.6.2"
libraryDependencies += "dev.zio" %% "zio-json" % "0.7.3"
```

## Example
Expand All @@ -50,15 +50,21 @@ into a Scala `case class`
case class Banana(curvature: Double)
```

To do this, we create an *instance* of the `JsonDecoder` typeclass for `Banana` using the `zio-json` code generator. It is best practice to put it on the companion of `Banana`, like so
To do this, we derive an *instance* of the `JsonDecoder` typeclass for `Banana`.

```scala
object Banana {
implicit val decoder: JsonDecoder[Banana] = DeriveJsonDecoder.gen[Banana]
}
case class Banana(curvature: Double) derives JsonDecoder
```

_Note: If you’re using Scala 3 and your case class is defining default parameters, `-Yretain-trees` needs to be added to `scalacOptions`._
> [!NOTE]
>
> In scala 2, we need to use the `zio-json` code generator. It is best practice to put it on the companion of `Banana`, like so
>
> ```scala
> object Banana {
> implicit val decoder: JsonDecoder[Banana] = DeriveJsonDecoder.gen[Banana]
> }
> ```

Now we can parse JSON into our object

Expand All @@ -67,13 +73,10 @@ scala> """{"curvature":0.5}""".fromJson[Banana]
val res: Either[String, Banana] = Right(Banana(0.5))
```

Likewise, to produce JSON from our data we define a `JsonEncoder`
Likewise, to produce JSON from our data we derive a `JsonEncoder`

```scala
object Banana {
...
implicit val encoder: JsonEncoder[Banana] = DeriveJsonEncoder.gen[Banana]
}
case class Banana(curvature: Double) derives JsonEncoder

scala> Banana(0.5).toJson
val res: String = {"curvature":0.5}
Expand All @@ -85,6 +88,16 @@ val res: String =
}
```

> [!NOTE]
>
> In scala 2:
> ```scala
> object Banana {
> ...
> implicit val encoder: JsonEncoder[Banana] = DeriveJsonEncoder.gen[Banana]
> }
> ```

And bad JSON will produce an error in `jq` syntax with an additional piece of contextual information (in parentheses)

```
Expand All @@ -95,20 +108,49 @@ val res: Either[String, Banana] = Left(.curvature(expected a number, got w))
Say we extend our data model to include more data types

```scala
sealed trait Fruit
case class Banana(curvature: Double) extends Fruit
case class Apple (poison: Boolean) extends Fruit
enum Fruit:
case Banana(curvature: Double) extends Fruit
case Apple(poison: Boolean) extends Fruit
```

we can generate the encoder and decoder for the entire `sealed` family
we can generate the encoder and decoder for the entire `sealed` family using `JsonCodec`

```scala
object Fruit {
implicit val decoder: JsonDecoder[Fruit] = DeriveJsonDecoder.gen[Fruit]
implicit val encoder: JsonEncoder[Fruit] = DeriveJsonEncoder.gen[Fruit]
}
enum Fruit derives JsonCodec:
case Banana(curvature: Double)
case Apple(poison: Boolean)
```

> [!NOTE]
>
> In scala 2:
>
> ```scala mdoc:compile-only
> import zio.json._
>
> sealed trait Fruit extends Product with Serializable
> case class Banana(curvature: Double) extends Fruit
> case class Apple(poison: Boolean) extends Fruit
>
> object Fruit {
> implicit val decoder: JsonDecoder[Fruit] =
> DeriveJsonDecoder.gen[Fruit]
>
> implicit val encoder: JsonEncoder[Fruit] =
> DeriveJsonEncoder.gen[Fruit]
> }
>
> val json1 = """{ "Banana":{ "curvature":0.5 }}"""
> val json2 = """{ "Apple": { "poison": false }}"""
> val malformedJson = """{ "Banana":{ "curvature": true }}"""
>
> json1.fromJson[Fruit]
> json2.fromJson[Fruit]
> malformedJson.fromJson[Fruit]
>
> List(Apple(false), Banana(0.4)).toJsonPretty
> ```

allowing us to load the fruit based on a single field type tag in the JSON

```
Expand All @@ -122,19 +164,13 @@ val res: Either[String, Fruit] = Right(Apple(false))
Almost all of the standard library data types are supported as fields on the case class, and it is easy to add support if one is missing.

```scala
import zio.json._
import zio.json.*

sealed trait Fruit extends Product with Serializable
case class Banana(curvature: Double) extends Fruit
case class Apple(poison: Boolean) extends Fruit
enum Fruit extends Product, Serializable derives JsonCodec:
case Banana(curvature: Double) extends Fruit
case Apple(poison: Boolean) extends Fruit

object Fruit {
implicit val decoder: JsonDecoder[Fruit] =
DeriveJsonDecoder.gen[Fruit]

implicit val encoder: JsonEncoder[Fruit] =
DeriveJsonEncoder.gen[Fruit]
}
export Fruit.*

val json1 = """{ "Banana":{ "curvature":0.5 }}"""
val json2 = """{ "Apple": { "poison": false }}"""
Expand Down
109 changes: 107 additions & 2 deletions docs/index.md → docs/index.mdx
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,9 @@ title: "Getting Started with ZIO Json"
sidebar_label: "Getting Started"
---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

[ZIO Json](https://github.com/zio/zio-json) is a fast and secure JSON library with tight ZIO integration.

@PROJECT_BADGES@
Expand Down Expand Up @@ -34,10 +37,23 @@ Let's try a simple example of encoding and decoding JSON using ZIO JSON.

All the following code snippets assume that the following imports have been declared

<Tabs groupId="language">
<TabItem value="scala 2" label="Scala 2">

```scala
import zio.json._
```

</TabItem>
<TabItem value="scala 3" label="Scala 3" default>

```scala
import zio.json.*
```

</TabItem>
</Tabs>

Say we want to be able to read some JSON like

```json
Expand All @@ -50,6 +66,9 @@ into a Scala `case class`
case class Banana(curvature: Double)
```

<Tabs groupId="language">
<TabItem value="scala 2" label="Scala 2">

To do this, we create an *instance* of the `JsonDecoder` typeclass for `Banana` using the `zio-json` code generator. It is best practice to put it on the companion of `Banana`, like so

```scala
Expand All @@ -58,7 +77,19 @@ object Banana {
}
```

_Note: If you’re using Scala 3 and your case class is defining default parameters, `-Yretain-trees` needs to be added to `scalacOptions`._
</TabItem>
<TabItem value="scala 3" label="Scala 3" default>

To do this, we derive an *instance* of the `JsonDecoder` typeclass for `Banana`.

```scala
case class Banana(curvature: Double) derives JsonDecoder
```

Note: If your case class is defining default parameters, -Yretain-trees needs to be added to scalacOptions.

</TabItem>
</Tabs>

Now we can parse JSON into our object

Expand All @@ -67,14 +98,29 @@ scala> """{"curvature":0.5}""".fromJson[Banana]
val res: Either[String, Banana] = Right(Banana(0.5))
```

Likewise, to produce JSON from our data we define a `JsonEncoder`
Likewise, to produce JSON from our data we derive a `JsonEncoder`

<Tabs groupId="language">
<TabItem value="scala 2" label="Scala 2">

```scala
object Banana {
...
implicit val encoder: JsonEncoder[Banana] = DeriveJsonEncoder.gen[Banana]
}
```

</TabItem>
<TabItem value="scala 3" label="Scala 3" default>

```scala
case class Banana(curvature: Double) derives JsonEncoder
```

</TabItem>
</Tabs>

```
scala> Banana(0.5).toJson
val res: String = {"curvature":0.5}

Expand All @@ -94,21 +140,51 @@ val res: Either[String, Banana] = Left(.curvature(expected a number, got w))

Say we extend our data model to include more data types

<Tabs groupId="language">
<TabItem value="scala 2" label="Scala 2">

```scala
sealed trait Fruit
case class Banana(curvature: Double) extends Fruit
case class Apple (poison: Boolean) extends Fruit
```

</TabItem>
<TabItem value="scala 3" label="Scala 3" default>

```scala
enum Fruit:
case Banana(curvature: Double) extends Fruit
case Apple (poison: Boolean) extends Fruit
```

</TabItem>
</Tabs>

we can generate the encoder and decoder for the entire `sealed` family

<Tabs groupId="language">
<TabItem value="scala 2" label="Scala 2">

```scala
object Fruit {
implicit val decoder: JsonDecoder[Fruit] = DeriveJsonDecoder.gen[Fruit]
implicit val encoder: JsonEncoder[Fruit] = DeriveJsonEncoder.gen[Fruit]
}
```

</TabItem>
<TabItem value="scala 3" label="Scala 3" default>

```scala
enum Fruit derives JsonCodec:
case Banana(curvature: Double)
case Apple (poison: Boolean)
```

</TabItem>
</Tabs>

allowing us to load the fruit based on a single field type tag in the JSON

```
Expand All @@ -121,6 +197,9 @@ val res: Either[String, Fruit] = Right(Apple(false))

Almost all of the standard library data types are supported as fields on the case class, and it is easy to add support if one is missing.

<Tabs groupId="language">
<TabItem value="scala 2" label="Scala 2">

```scala mdoc:compile-only
import zio.json._

Expand All @@ -147,6 +226,32 @@ malformedJson.fromJson[Fruit]
List(Apple(false), Banana(0.4)).toJsonPretty
```

</TabItem>
<TabItem value="scala 3" label="Scala 3" default>

```scala
import zio.json.*

enum Fruit extends Product, Serializable derives JsonCodec:
case Banana(curvature: Double) extends Fruit
case Apple(poison: Boolean) extends Fruit

export Fruit.*

val json1 = """{ "Banana":{ "curvature":0.5 }}"""
val json2 = """{ "Apple": { "poison": false }}"""
val malformedJson = """{ "Banana":{ "curvature": true }}"""

json1.fromJson[Fruit]
json2.fromJson[Fruit]
malformedJson.fromJson[Fruit]

List(Apple(false), Banana(0.4)).toJsonPretty
```

</TabItem>
</Tabs>

# How

Extreme **performance** is achieved by decoding JSON directly from the input source into business objects (inspired by [plokhotnyuk](https://github.com/plokhotnyuk/jsoniter-scala)). Although not a requirement, the latest advances in [Java Loom](https://wiki.openjdk.java.net/display/loom/Main) can be used to support arbitrarily large payloads with near-zero overhead.
Expand Down