telemux

telemux

Flexible message router add-on for go-telegram-bot-api library.

Table of contents

• Motivation
• Features
• Minimal example
• Documentation
• Changelog
• Terminology
  • Mux
  • Handlers & filters
    • Combining filters
    • Reusable handler functions
  • Conversations & persistence
  • Error handling
• Tips & common pitfalls
  • tgbotapi.Update vs tm.Update confusion
  • Getting user/chat/message object from update
  • Properly filtering updates

Motivation

This library serves as an addition to the go-telegram-bot-api library. I strongly recommend you to take a look at it since telemux is mostly an extension to it.

Patterns such as handlers, persistence & filters were inspired by a wonderful python-telegram-bot library.

This project is in early beta stage. Contributions are welcome! Feel free to submit an issue if you have any questions, suggestions or simply want to help.

Features

• Extension for go-telegram-bot-api library, meaning you'll still use all of its features
• Designed with statelessness in mind
• Extensible handler configuration inspired by python-telegram-bot library
• Conversations (aka Dialogs) based on finite-state machines (see ./examples/album_conversation/main.go)
• Pluggable persistence for conversations. E. g. you can use database to store the states & intermediate values of conversations (see ./examples/album_conversation/main.go and ./persistence.go)
• Support for GORM as a persistence backend via module
• Flexible handler filtering. E. g. And(Or(HasText(), HasPhoto()), IsPrivate()) will only accept direct messages containing photo or text (see ./filters.go)

Minimal example

package main

import (
    tm "github.com/and3rson/telemux"
    tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api"
    "os"
)

func main() {
    // This part is a boilerplate from go-telegram-bot-api library.
    bot, _ := tgbotapi.NewBotAPI(os.Getenv("TG_TOKEN"))
    bot.Debug = true
    u := tgbotapi.NewUpdate(0)
    u.Timeout = 60
    updates, _ := bot.GetUpdatesChan(u)

    // Create a multiplexer with two handlers: one for command and one for all messages.
    // If a handler cannot handle the update (fails the filter),
    // multiplexer will proceed to the next handler.
    mux := tm.NewMux().
        AddHandler(tm.NewCommandHandler(
            "start",
            func(u *tm.Update) {
                bot.Send(tgbotapi.NewMessage(u.Message.Chat.ID, "Hello! Say something. :)"))
            },
        )).
        AddHandler(tm.NewHandler(
            tm.Any(),
            func(u *tm.Update) {
                bot.Send(tgbotapi.NewMessage(u.Message.Chat.ID, "You said: "+u.Message.Text))
            },
        ))
    // Dispatch all telegram updates to multiplexer
    for update := range updates {
        mux.Dispatch(bot, update)
    }
}

Documentation

The documentation is available here.

Examples are available here.

Changelog

Changelog is available here.

Terminology

Mux

Mux (multiplexer) is a "router" for instances of tgbotapi.Update.

It allows you to register handlers and will take care to choose an appropriate handler based on the incoming update.

In order to work, you must dispatch messages (that come from go-telegram-bot-api channel):

mux := tm.NewMux()
// ...
// add handlers to mux here
// ...
updates, _ := bot.GetUpdatesChan(u)
for update := range updates {
    mux.Dispatch(bot, update)
}

You can also nest Mux instances:

// See "Handlers & filters" section below for more info on filters.
mux_a := tm.NewMux().
    SetGlobalFilter(tm.IsPrivate()).
    AddHandler(/* ... */).
    AddHandler(/* ... */)
mux_b := tm.NewMux().
    SetGlobalFilter(tm.IsGroupOrSuperGroup()).
    AddHandler(/* ... */).
    AddHandler(/* ... */)
mux = tm.NewMux().
    AddMux(mux_a).
    AddMux(mux_b).
    AddHandler(/* ... */)

Handlers & filters

Handler consists of filter and handle-function.

Handler's filter decides whether this handler can handle the incoming update. If so, handle-function is called. Otherwise multiplexer will proceed to the next handler.

Filters are divided in two groups: content filters (starting with "Has", such as HasPhoto(), HasAudio(), HasSticker() etc) and update type filters (starting with "Is", such as IsEditedMessage(), IsInlineQuery() or IsGroupOrSuperGroup()).

There is also a special filter Any() which makes handler accept all updates.

Filters can also be applied to the Mux instance using mux.SetGlobalFilter(filter). Such filters will be called for every update before any other filters.

Generic handlers can be created with tm.NewHandler function, however there are shortcuts for adding update-type-specific handlers:

tm.NewMessageHandler(tm.HasPhoto(), func(u *tm.Update) { /* ... */ })
# ...equals to: tm.NewHandler(tm.And(tm.IsMessage(), tm.HasPhoto()), func(u *tm.Update) { /* ... */ })

tm.NewCommandHandler("start", tm.IsPrivate(), func(u *tm.Update) { /* ... */ })
# ...equals to: tm.NewHandler(tm.And(tm.IsCommandMessage("start"), tm.IsPrivate()), func(u *tm.Update) { /* ... */ })

tm.NewCallbackQueryHandler(nil, func(u *tm.Update) { /* ... */ })
# ...equals to: tm.NewHandler(tm.IsCallbackQuery(), func(u *tm.Update) { /* ... */ })

# etc.

Combining filters

Filters can be chained using And, Or, and Not meta-filters. For example:

mux := tm.NewMux()

// Add handler that accepts photos sent to the bot in a private chat:
mux.AddHandler(And(tm.IsPrivate(), tm.HasPhoto()), func(u *tm.Update) { /* ... */ })

// Add handler that accepts photos and text messages:
mux.AddHandler(Or(tm.HasText(), tm.HasPhoto()), func(u *tm.Update) { /* ... */ })

// Since filters are plain functions, you can easily implement them yourself.
// Below we add handler that allows onle a specific user to call "/restart" command:
mux.AddHandler(tm.NewHandler(
    tm.And(tm.IsCommandMessage("restart"), func(u *tm.Update) bool {
        return u.Message.From.ID == 3442691337
    }),
    func(u *tm.Update) { /* ... */ },
))

Reusable handler functions

mux.NewHandler can accept more than one handler function. They are all executed sequentially. The chain can be interrupted by any of them by calling u.Consume().

Here is an example:

mux.AddHandler(tm.NewHandler(
    tm.IsCommandMessage("do_work"),
    func(u *tm.Update) {
        // Perform necessary check
        if u.EffectiveUser().ID != 3442691337 { // Boilerplate code that will be copy-pasted way too much
            u.Bot.Send(tgbotapi.Message(u.EffectiveChat().ID, "You are not allowed to ask me to work!"))
            // Stop handling
            return
        }
        // Perform another check
        if !u.EffectiveChat().IsPrivate() { // Another boilerplate code
            u.Bot.Send(tgbotapi.Message(u.EffectiveChat().ID, "I do not accept commands in group chats. Send me a PM."))
            // Stop handling
            return
        }
        // All checks passed, do some actual work
        // ...
    },
))

To avoid repeating boilerplate checks like if user is not "3442691337" then send error and stop, you can move them to separate functions.

The above code can be rewritten as follows:

// CheckAdmin is a reusable handler that not only checks for user's ID but marks update as processed as well
func CheckAdmin(u *tm.Update) {
    if u.EffectiveUser().ID != 3442691337 {
        u.Bot.Send(tgbotapi.Message(u.EffectiveChat().ID, "You are not allowed to ask me to work!"))
        u.Consume() // Mark update as consumed. Following handler functions will not be called.
    }
}

// CheckPrivate is a reusable handler that not only checks for private chat but marks update as processed as well
func CheckPrivate(u *tm.Update) {
    if !u.EffectiveChat().IsPrivate() {
        u.Bot.Send(tgbotapi.Message(u.EffectiveChat().ID, "I do not accept commands in group chats. Send me a PM."))
        u.Consume() // Mark update as consumed. Following handler functions will not be called.
    }
}

// ...

mux.AddHandler(tm.NewHandler(
    tm.IsCommandMessage("do_work"),
    CheckAdmin,
    CheckPrivate,
    func(u *tm.Update) {
        // Do actual work
    },
))
mux.AddHandler(tm.NewHandler(
    tm.IsCommandMessage("other_command")),
    func(u *tm.Update) {
        // This handler will not fire if one of previous handlers (CheckAdmin or CheckPrivate) consumed the update.
    },
))

You can implement some more complex handler functions, for example, a parametrized one:

// CheckUserID checks for specific user ID and marks update processed if check fails
func RequireUserID(userID int) tm.HandleFunc {
    return func(u *tm.Update) {
        if u.EffectuveUser().ID != userID {
            u.Bot.Send(tgbotapi.NewMessage(u.EffectiveChat().ID, "Sorry, I don't know you!"))
            u.Consume()
        }
    }
}

// ...

mux.AddHandler(tm.NewHandler(
    tm.IsCommandMessage("do_work"),
    RequireUserID(3442691337),
    func(u *tm.Update) {
        // Do actual work
    },
))

Conversations & persistence

Conversations are handlers on steroids based on the finite-state machine pattern.

They allow you to have complex dialog interactions with different handlers.

Persistence interface tells conversation where to store & how to retrieve the current state of the conversation, i. e. which "step" the given user is currently at.

To create a ConversationHandler you need to provide the following:

• conversationID string - identifier that distinguishes this conversation from the others.

  The main goal of this identifier is to allow persistence to keep track of different conversation states independently without mixing them together.

• persistence Persistence - defines where to store conversation state & intermediate inputs from the user.

  Without persistence, a conversation would not be able to "remember" what "step" the user is at.

  Persistence is also useful when you want to collect some data from the user step-by-step).

  Two convenient implementations of Persistence are available out of the box: LocalPersistence & FilePersistence.

  Telemux also supports GORM persistence. If you use GORM, you can store conversation states & data in your database by using GORMPersistence from a module.

• states StateMap - defines what handlers to use in which state.

  States are usually strings like "upload_photo", "send_confirmation", "wait_for_text" and describe the "step" the user is currently at. Empty string ("") should be used as an initial/final state (i. e. if the conversation has not started yet or has already finished.)

  For each state you must provide a slice with at least one Handler. If none of the handlers can handle the update, the default handlers are attempted (see below).

  In order to switch to a different state your Handler must call u.PersistenceContext.SetState("STATE_NAME") replacing STATE_NAME with the name of the state you want to switch into.

  Conversation data can be accessed with u.PersistenceContext.GetData() and updated with u.PersistenceContext.SetData(newData).

• defaults []*Handler - these handlers are "appended" to every state.

  Useful to handle commands such as "/cancel" or to display some default message.

See ./examples/album_conversation/main.go for a conversation example.

Error handling

By default, panics in handlers are propagated all the way to the top (Dispatch method).

In order to intercept all panics in your handlers globally and handle them gracefully, register your function using SetRecover:

mux := tm.NewMux()
# ...
mux.SetRecover(func(u *tm.Update, err error, stackTrace string) {
    fmt.Printf("An error occurred: %s\n\nStack trace:\n%s", err, stackTrace)
})

Tips & common pitfalls

tgbotapi.Update vs tm.Update confusion

Since Update struct from go-telegram-bot-api already provides most of the functionality, telemux implements its own Update struct which embeds the Update from go-telegram-bot-api. Main reason for this is to add some extra convenient methods and include Bot instance with every update.

Getting user/chat/message object from update

When having handlers for wide filters (e. g. Or(And(HasText(), IsEditedMessage()), IsInlineQuery())) you may often fall in situations when you need to check for multiple user/chat/message attributes. In such situations sender's data may be in one of few places depending on which update has arrived: u.Message.From, u.EditedMessage.From, or u.InlineQuery.From. Similar issue applies to fetching actual chat info or message object from an update.

In such cases it's highly recommended to use functions such as EffectiveChat() (see the update module for more info):

// Bad:
fmt.Println(u.Message.Chat.ID) // u.Message may be nil

// Better, but not so DRY:
chatId int64
if u.Message != nil {
    chatId = u.Message.Chat.ID
} else if u.EditedMessage != nil {
    chatId = u.EditedMessage.Chat.ID
} else if u.CallbackQuery != nil {
    chatId = u.CallbackQuery.Chat.ID
} // And so on... Duh.
fmt.Println(chatId)

// Best:
chat := u.EffectiveChat()
if chat != nil {
    fmt.Println(chat.ID)
}

Properly filtering updates

Keep in mind that using content filters such as HasText(), HasPhoto(), HasLocation(), HasVoice() etc does not guarantee that the Update describes an actual new message. In fact, an Update also happens when a user edits his message! Thus your handler will be executed even if a user just edited one of his messages.

To avoid situations like these, make sure to use filters such as IsMessage(), IsEditedMessage(), IsCallbackQuery() etc in conjunction with content filters. For example:

tm.NewHandler(HasText(), func(u *tm.Update) { /* ... */ }) // Will handle new messages, updated messages, channel posts & channel post edits which contain text
tm.NewHandler(And(IsMessage(), HasText()), func(u *tm.Update) { /* ... */ }) // Will handle new messages that contain text
tm.NewHandler(And(IsEditedMessage(), HasText()), func(u *tm.Update) { /* ... */ }) // Will handle edited that which contain text

The only exceptions are IsCommandMessage("...") and IsAnyCommandMessage() filters. Since it does not make sense to react to edited messages that contain commands, this filter also checks if the update designates a new message and not an edited message, inline query, callback query etc. This means you can safely use IsCommandMessage("my_command") without joining it with the IsMessage() filter:

IsCommandMessage("my_command") // OK: IsCommand() already checks for IsMessage()
And(IsCommandMessage("start"), IsMessage()) // IsMessage() is unnecessary
And(IsCommandMessage("start"), Not(IsEditedMessage())) // Not(IsEditedMessage()) is unnecessary