Vendelieu Telegram Bot Build Wizard Flow

Build Wizard Flow

Quick Start

Annotate an object/class with @WizardHandler. Define nested steps extending WizardStep. KSP generates the WizardActivity; no manual Activity class needed.

import eu.vendeli.tgbot.types.component.MessageUpdate

@WizardHandler(trigger = ["/start"])
object RegistrationWizard {
    object NameStep : WizardStep(isInitial = true) {
        override suspend fun onEntry(ctx: WizardContext) {
            message("What's your name?").send(ctx.user, ctx.bot)
        }
        override suspend fun validate(ctx: WizardContext): Transition {
            val text = (ctx.update as? MessageUpdate)?.message?.text ?: return Transition.Retry()
            return if (text.isNotBlank()) Transition.Next else Transition.Retry("Invalid name")
        }
        override suspend fun store(ctx: WizardContext): String? =
            (ctx.update as? MessageUpdate)?.message?.text
    }

    object AgeStep : WizardStep() {
        override suspend fun onEntry(ctx: WizardContext) {
            message("How old are you?").send(ctx.user, ctx.bot)
        }
        override suspend fun validate(ctx: WizardContext): Transition {
            val age = (ctx.update as? MessageUpdate)?.message?.text?.toIntOrNull()
            return if (age != null && age in 1..150) Transition.Next else Transition.Retry()
        }
        override suspend fun store(ctx: WizardContext): Int? =
            (ctx.update as? MessageUpdate)?.message?.text?.toIntOrNull()
    }
}

WizardStep Lifecycle

• onEntry(ctx) — Called when entering the step. Send prompts, set keyboards.
• validate(ctx) — Return Transition based on input.
• store(ctx) — Return value to persist (or null). Type must match a state manager.
• onRetry(ctx, reason) — Called when validation fails (optional).

Transitions

State Managers

Default: MapStringStateManager, MapIntStateManager, MapLongStateManager. KSP matches store() return type to the manager.

Override per step:

@WizardHandler.StateManager(CustomStateManager::class)
object CustomStep : WizardStep { ... }

WizardContext

• ctx.user, ctx.update, ctx.bot
• ctx.getState(Step::class), ctx.setState(Step::class, value), ctx.delState(Step::class) — type-safe accessors generated by KSP for each step

Trigger and Scope

• trigger = ["/start", "/register"] — commands that start the wizard
• scope = [UpdateType.MESSAGE] — default; use UpdateType.CALLBACK_QUERY for button-triggered wizards

Related Skills

• add-wizard-handler — Configure @WizardHandler (trigger, scope, state managers)
• add-wizard-step — Implement WizardStep (onEntry, validate, store, transitions)

Reference

• WizardHandler.kt
• WizardStep.kt
• TestWizard.kt

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