C# Telegram bot: get chat_id

In C# Telegram bots (Telegram.Bot library), you get chat_id and user_id from the update. Here are examples.

From a message

botClient.OnMessage(async (client, update, cancellationToken) =>
{
    var message = update.Message;
    if (message == null) return;

    var chatId = message.Chat.Id;
    var userId = message.From?.Id;

    await client.SendTextMessageAsync(
        chatId,
        $"Chat ID: {chatId}, User ID: {userId}",
        cancellationToken: cancellationToken);
});

message.Chat.Id — chat_id
message.From?.Id — sender’s Telegram user ID

From a callback query

botClient.OnCallbackQuery(async (client, update, cancellationToken) =>
{
    var query = update.CallbackQuery;
    var chatId = query.Message.Chat.Id;
    var userId = query.From.Id;

    await client.AnswerCallbackQueryAsync(query.Id, cancellationToken: cancellationToken);
    await client.SendTextMessageAsync(
        chatId,
        $"Chat ID: {chatId}, User ID: {userId}",
        cancellationToken: cancellationToken);
});

From channel post

botClient.OnChannelPost(async (client, update, cancellationToken) =>
{
    var post = update.ChannelPost;
    var chatId = post.Chat.Id;  // channel ID

    await client.SendTextMessageAsync(
        chatId,
        $"Channel ID: {chatId}",
        cancellationToken: cancellationToken);
});

Debugging with @print_id_bot

Use @print_id_bot to inspect the raw update:

/json — Message as JSON. Compare with your Update object.
/dump — Full update and raw JSON (private chat only). Use to verify structure.

Forward a message to the bot and send /dump to see the exact format.

FAQ

How do I get chat_id when the bot is added to a group?

When a user sends a message, your handler receives it with Message.Chat.Id. Or add @print_id_bot and send /id to get it manually.

What type is Chat.Id?

long (Int64). Telegram IDs can be large; use the correct type.

Where is the update structure?

The Telegram Bot API documents it. Use /dump in @print_id_bot for real examples.

What if Message.From is null?

For channel_post, there is no From. Use null-conditional: message.From?.Id.

Can I serialize the update to JSON?

Yes. Serialize the Update object and compare with /dump output from @print_id_bot.

Use @print_id_bot /dump to inspect update structure for C# bots.

Open @print_id_bot