Serialization¶

The generator can annotate records and enums with @kotlinx.serialization.Serializable, so they can be encoded with kotlinx.serialization directly:

# uniffi.toml
generate_serializable_records = true

The module also needs the serialization compiler plugin and a format:

plugins {
    kotlin("multiplatform")
    kotlin("plugin.serialization") version "2.4.0"
    id("ch.ubique.uniffi.plugin")
}

kotlin.sourceSets.commonMain.dependencies {
    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:<version>")
}

#[derive(uniffi::Record)]
pub struct Values {
    pub a: i64,
    pub b: i64,
}

Json.encodeToString(Values(4, 2))                   // {"a":4,"b":2}
Json.decodeFromString<Values>("""{"a":13,"b":37}""")

Field names¶

Fields are serialised under their Rust name (@SerialName("user_id")). When decoding, the Kotlin name (userId) is accepted too (@JsonNames). JSON produced by Rust's serde with default settings can be read as is.

What gets annotated¶

	Annotated
Records	always, unless listed in skip_serializer_for
Enums	unless they contain objects or are listed in skip_serializer_for

A record whose fields can't be serialised, for example because it contains an object or a custom type mapped to a non-serialisable Kotlin class, fails to compile. Exclude it by name:

generate_serializable_records = true
skip_serializer_for = ["Session", "Cursor"]

Fixtures¶

• tests/uniffi/serialization