# kotlinx.serialization Decode @Serializable classes directly from JSON on the JVM. The `simdjson-kotlin-serialization` module plugs simdjson-kotlin into [kotlinx.serialization](https://github.com/Kotlin/kotlinx.serialization): decode JSON straight into your `@Serializable` classes, with simdjson doing the parsing. ## Decoding Annotate your models with `@Serializable`, create a `SimdJson` instance, and decode: ```kotlin import io.github.devcrocod.simdjson.serialization.SimdJson import kotlinx.serialization.Serializable @Serializable data class Twitter(val statuses: List) @Serializable data class Status(val user: User) @Serializable data class User(val default_profile: Boolean, val screen_name: String) val json: String = loadTwitterJson() val simdJson = SimdJson { ignoreUnknownKeys = true } for (status in simdJson.decodeFromString(json).statuses) { if (status.user.default_profile) { println(status.user.screen_name) } } ``` To decode from a UTF-8 `ByteArray` (skipping the `String` step), use `decodeFromByteArray` with an explicit serializer: ```kotlin import kotlinx.serialization.serializer val twitter = simdJson.decodeFromByteArray(serializer(), bytes) ``` ## Configuration `SimdJson { }` builds an instance via a builder, mirroring kotlinx.serialization's `Json { }`:

Parameter	Description
`ignoreUnknownKeys`Boolean	Skip JSON keys with no matching property instead of failing. Default `false`.
`isLenient`Boolean	Relax the input grammar when reading values. Default `false`.
`coerceInputValues`Boolean	Substitute the property default for a missing or `null`-for-non-null value. Default `false`.
`serializersModule`SerializersModule	Register contextual or polymorphic serializers.

## Decoding only