Customizing

The client can be customized via dependency injection:

matrixClient.create(...){
    modulesFactories += ::createCustomModule
}

fun createCustomModule() = module {
    single<EventContentSerializerMappings> {
        EventContentSerializerMappings.default + customMappings
    }
}

Be aware to always create new modules because a module saves your class instances and therefore is reused, which usually is not wanted!

Custom events

One goal in developing Trixnity was the ability to add custom events. This is achieved by mapping event types to serializers. In this example, we added a new message event: de.connect2x.dino. As a developer, you can then receive events of this Kotlin type like all other default events.

@Serializable
data class DinoEventContent(
    val dinoCount: Long,
) : MessageEventContent {
    // just ignore these properties when you don't need them
    override val relatesTo: RelatesTo? = null
    override val mentions: Mentions? = null
    override val externalUrl: String? = null
}

val customMappings = EventContentSerializerMappings { // add this to the modulesFactories (see example above)
    messageOf<DinoEventContent>("de.connect2x.dino")
}

It is also possible to add custom extensible events and content blocks. They also provide backwards compatibility via legecy. For simplicity the latter is ignored in this example. If you want to support legacy events, take a look at TopicEventContent.

val customMappings = EventContentSerializerMappings {
    blockOf(DinoContentBlock)
    messageOf<DinoEventContent>("de.connect2x.dino")
}

@Serializable
@JvmInline
value class DinoContentBlock(
    private val dinoCount: Long,
) : EventContentBlock.Default {
    override val type: EventContentBlock.Type<*> get() = Type

    companion object Type : EventContentBlock.Type<DinoContentBlock> {
        override val value: String = "de.connect2x..dino"
    }
}

@Serializable(DinoEventContent.Serializer::class)
data class DinoEventContent(
    override val blocks: EventContentBlocks,
) : StateEventContent, ExtensibleEventContent<ExtensibleEventContent.Legacy.None> {
    // this is just a convenience constructor
    constructor(dinoCount: Long) : this(
        EventContentBlocks(DinoContentBlock(dinoCount)),
    )

    val dinoCount: Long? = blocks[DinoContentBlock]?.dinoCount
    override val legacy: ExtensibleEventContent.Legacy.None? = null
    override val externalUrl: String? = null

    object Serializer : ExtensibleEventContentSerializer<ExtensibleEventContent.Legacy.None, DinoEventContent>(
        "DinoEventContent",
        { blocks: EventContentBlocks, _ -> DinoEventContent(blocks) },
        ExtensibleEventContent.Legacy.None.serializer()
    )
}