State Management Example Bot

In this example section, we will create a bot that demonstrates Telegram's state management system. The bot will guide users through a multi-step conversation to collect their name and age, using states to maintain context between interactions.

We will use the following handlers:

onMessage with filter.commands() for command triggers
onMessage with filter.state() for state-specific message handling

Import necessary classes

package io.github.natanimn;

import io.github.natanimn.telebof.BotClient;
import io.github.natanimn.telebof.BotContext;
import io.github.natanimn.telebof.enums.ParseMode;
import io.github.natanimn.telebof.types.updates.Message;

Create StateExampleBot class and initialize BotClient with state handlers

public class StateExampleBot {

    BotClient bot;

    public StateExampleBot(String token){
        bot = new BotClient(token);

        // Register handlers for different states and commands
        bot.onMessage(filter -> filter.commands("start"), this::start);
        bot.onMessage(filter -> filter.commands("cancel") && filter.state("*"), this::cancel);
        bot.onMessage(filter -> filter.state("name") && filter.text(), this::getName);
        bot.onMessage(filter -> filter.state("age") && filter.text(), this::getAge);
    }
}

Our bot will manage the following conversation flow using states:

/start command → Sets state to "name" and asks for user's name
User provides name → Sets state to "age" and asks for age
User provides age → Processes both pieces of information and clears state
/cancel command → Clears current state at any point in the conversation

State Handlers Implementation

1. Start Handler - Initiating the Conversation

The /start command begins the multi-step interaction by setting the initial state.

private void start(BotContext ctx, Message message){
    // Ask for the user's name
    ctx.sendMessage(message.from.id, "Hey! What is your name?").exec();

    // Set the user's state to "name" to indicate we're expecting their name next
    ctx.setState(message.from.id, "name");
}

Explanation:

setState(user_id, "name") marks that this user is now in the "name" state
The next message from this user will be processed by the getName handler

2. Name Handler - Collecting the Name

This handler is triggered when a user in the "name" state sends any message.

private void getName(BotContext ctx, Message message){
    // Ask for the user's age
    ctx.sendMessage(message.from.id, "How old are you?").exec();

    // Transition to the "age" state
    ctx.setState(message.from.id, "age");

    // Store the provided name in state data for later use
    var data = ctx.getStateData(message.from.id);
    data.put("name", message.text);
}

Key Concepts:

filter.state("name") ensures this handler only processes messages from users in the "name" state
filter.text() ensures that user only enter text
getStateData(user_id) retrieves a Map where we can store temporary conversation data
data.put("name", message.text) saves the user's name for the final summary

3. Age Handler - Collecting and Processing Age

This handler processes messages from users in the "age" state.

private void getAge(BotContext ctx, Message message){
    int age;

    // Validate that the input is a number
    try {
        age = Integer.parseInt(message.text);
    } catch (NumberFormatException e) {
        ctx.sendMessage(message.from.id, "Please enter a valid number").exec();
        return; // Stay in the "age" state until valid input is provided
    }

    // Retrieve the stored name from state data
    var data = ctx.getStateData(message.from.id);

    // Send confirmation message
    ctx.sendMessage(message.from.id, "Thank you for the information you have provided.").exec();

    // Display the collected information
    ctx.sendMessage(message.from.id, 
            String.format("<b>Name:</b> %s\n<b>Age:</b> %d", data.get("name"), age))
            .parseMode(ParseMode.HTML)
            .exec();

    // The state is automatically cleared after the conversation completes
    ctx.clearState(message.from.id);
}

Explanation:

Input validation ensures we get a valid age before proceeding
data.get("name") retrieves the name stored in the previous step
The state is automatically handled by the framework after completion

4. Cancel Handler - Aborting the Conversation

The /cancel command can be used at any point to abort the current conversation.

private void cancel(BotContext ctx, Message message){
    // Clear the user's current state and any stored data
    ctx.clearState(message.from.id);

    ctx.sendMessage(message.from.id, 
            "Your information has been cleared. Type /start to begin again.").exec();
}

Key Feature:

filter.state("*") matches users in any active state, allowing cancellation from any step
clearState(user_id) removes both the state marker and any associated data

Running the Bot

public void run(){
    bot.startPolling();
}

public static void main(String[] args){
    var token = System.getenv("TOKEN"); // Get token from environment variable
    var state_bot = new StateExampleBot(token);
    state_bot.run();
}

Conversation Flow Example

User sends /start → Bot sets state to "name" and asks for name
User provides name → Bot stores name, sets state to "age", asks for age
User provides age → Bot displays collected information
(Optional) User can send /cancel at any time to abort the process

The full source code can be found on examples/state_bot