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go-tg

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go-tg is a Go client library for accessing Telegram Bot API, with batteries for building complex bots included.

⚠️ Although the API definitions are considered stable package is well tested and used in production, please keep in mind that go-tg is still under active development and therefore full backward compatibility is not guaranteed before reaching v1.0.0.

Features

Install

# go 1.18+
go get -u github.com/mr-linch/go-tg

Quick Example

package main

import (
  "context"
  "fmt"
  "os"
  "os/signal"
  "regexp"
  "syscall"
  "time"

  "github.com/mr-linch/go-tg"
  "github.com/mr-linch/go-tg/tgb"
)

func main() {
  ctx := context.Background()

  ctx, cancel := signal.NotifyContext(ctx, os.Interrupt, os.Kill, syscall.SIGTERM)
  defer cancel()

  if err := run(ctx); err != nil {
    fmt.Println(err)
    defer os.Exit(1)
  }
}

func run(ctx context.Context) error {
  client := tg.New(os.Getenv("BOT_TOKEN"))

  router := tgb.NewRouter().
    // handles /start and /help
    Message(func(ctx context.Context, msg *tgb.MessageUpdate) error {
      return msg.Answer(
        tg.HTML.Text(
          tg.HTML.Bold("👋 Hi, I'm echo bot!"),
          "",
          tg.HTML.Italic("🚀 Powered by", tg.HTML.Spoiler(tg.HTML.Link("go-tg", "github.com/mr-linch/go-tg"))),
        ),
      ).ParseMode(tg.HTML).DoVoid(ctx)
    }, tgb.Command("start", tgb.WithCommandAlias("help"))).
    // handles gopher image
    Message(func(ctx context.Context, msg *tgb.MessageUpdate) error {
      if err := msg.Update.Reply(ctx, msg.AnswerChatAction(tg.ChatActionUploadPhoto)); err != nil {
        return fmt.Errorf("answer chat action: %w", err)
      }

      // emulate thinking :)
      time.Sleep(time.Second)

      return msg.AnswerPhoto(
        tg.NewFileArgURL("https://go.dev/blog/go-brand/Go-Logo/PNG/Go-Logo_Blue.png"),
      ).DoVoid(ctx)

    }, tgb.Regexp(regexp.MustCompile(`(?mi)(go|golang|gopher)[$\s+]?`))).
    // handle other messages
    Message(func(ctx context.Context, msg *tgb.MessageUpdate) error {
      return msg.Copy(msg.Chat).DoVoid(ctx)
    }).
    MessageReaction(func(ctx context.Context, reaction *tgb.MessageReactionUpdate) error {
			// sets same reaction to the message
			answer := tg.NewSetMessageReactionCall(reaction.Chat, reaction.MessageID).Reaction(reaction.NewReaction)
			return reaction.Update.Reply(ctx, answer)
		})

  return tgb.NewPoller(
    router,
    client,
    tgb.WithPollerAllowedUpdates(
			tg.UpdateTypeMessage,
      tg.UpdateTypeMessageReaction,
    )
  ).Run(ctx)
}

More examples can be found in examples.

API Client

Creating

The simplest way for create client it's call tg.New with token. That constructor use http.DefaultClient as default client and api.telegram.org as server URL:

client := tg.New("<TOKEN>") // from @BotFather

With custom http.Client:

proxyURL, err := url.Parse("http://user:pass@ip:port")
if err != nil {
  return err
}

httpClient := &http.Client{
  Transport: &http.Transport{
    Proxy: http.ProxyURL(proxyURL),
  },
}

client := tg.New("<TOKEN>",
 tg.WithClientDoer(httpClient),
)

With self hosted Bot API server:

client := tg.New("<TOKEN>",
 tg.WithClientServerURL("http://localhost:8080"),
)

Bot API methods

All API methods are supported with embedded official documentation. It's provided via Client methods.

e.g. getMe call:

me, err := client.GetMe().Do(ctx)
if err != nil {
 return err
}

log.Printf("authorized as @%s", me.Username)

sendMessage call with required and optional arguments:

peer := tg.Username("MrLinch")

msg, err := client.SendMessage(peer, "<b>Hello, world!</b>").
  ParseMode(tg.HTML). // optional passed like this
  Do(ctx)

if err != nil {
  return err
}

log.Printf("sended message id %d", msg.ID)

Some Bot API methods do not return the object and just say True. So, you should use the DoVoid method to execute calls like that.

All calls with the returned object also have the DoVoid method. Use it when you do not care about the result, just ensure it's not an error (unmarshaling also be skipped).

peer := tg.Username("MrLinch")

if err := client.SendChatAction(
  peer,
  tg.ChatActionTyping
).DoVoid(ctx); err != nil {
  return err
}

Low-level Bot API methods call

Client has method Do for low-level requests execution:

req := tg.NewRequest("sendChatAction").
  PeerID("chat_id", tg.Username("@MrLinch")).
  String("action", "typing")

if err := client.Do(ctx, req, nil); err != nil {
  return err
}

Helper methods

Method Client.Me() fetches authorized bot info via Client.GetMe() and cache it between calls.

me, err := client.Me(ctx)
if err != nil {
  return err
}

Sending files

There are several ways to send files to Telegram:

The FileArg type is used to combine all these methods. It is an object that can be passed to client methods and depending on its contents the desired method will be chosen to send the file.

Consider each method by example.

Uploading a file along with a method call:

For upload a file you need to create an object tg.InputFile. It is a structure with two fields: file name and io.Reader with its contents.

Type has some handy constructors, for example consider uploading a file from a local file system:

inputFile, err := tg.NewInputFileLocal("/path/to/file.pdf")
if err != nil {
  return err
}
defer inputFile.Close()

peer := tg.Username("MrLinch")

if err := client.SendDocument(
  peer,
  tg.NewFileArgUpload(inputFile),
).DoVoid(ctx); err != nil {
	return err
}

Loading a file from a buffer in memory:


buf := bytes.NewBufferString("<html>...</html>")

inputFile := tg.NewInputFile("index.html", buf)

peer := tg.Username("MrLinch")

if err := client.SendDocument(
  peer,
  tg.NewFileArgUpload(inputFile),
).DoVoid(ctx); err != nil {
	return err
}

Sending a file using a URL from the Internet:

peer := tg.Username("MrLinch")

if err := client.SendPhoto(
  peer,
  tg.NewFileArgURL("https://picsum.photos/500"),
).DoVoid(ctx); err != nil {
	return err
}

Sending a previously uploaded file by its identifier:

peer := tg.Username("MrLinch")

if err := client.SendPhoto(
  peer,
  tg.NewFileArgID(tg.FileID("AgACAgIAAxk...")),
).DoVoid(ctx); err != nil {
	return err
}

Please checkout examples with "File Upload" features for more usecases.

Downloading files

To download a file you need to get its FileID. After that you need to call method Client.GetFile to get metadata about the file. At the end we call method Client.Download to fetch the contents of the file.


fid := tg.FileID("AgACAgIAAxk...")

file, err := client.GetFile(fid).Do(ctx)
if err != nil {
  return err
}

f, err := client.Download(ctx, file.FilePath)
if err != nil {
  return err
}
defer f.Close()

// ...

Interceptors

Interceptors are used to modify or process the request before it is sent to the server and the response before it is returned to the caller. It's like a [tgb.Middleware], but for outgoing requests.

All interceptors should be registered on the client before the request is made.

client := tg.New("<TOKEN>",
  tg.WithClientInterceptors(
    tg.Interceptor(func(ctx context.Context, req *tg.Request, dst any, invoker tg.InterceptorInvoker) error {
      started := time.Now()

      // before request
      err := invoker(ctx, req, dst)
      // after request

      log.Print("call %s took %s", req.Method, time.Since(started))

      return err
    }),
  ),
)

Arguments of the interceptor are:

Contrib package has some useful interceptors:

Interceptors are called in the order they are registered.

Example of using retry flood interceptor: examples/retry-flood

Updates

Everything related to receiving and processing updates is in the tgb package.

Handlers

You can create an update handler in three ways:

  1. Declare the structure that implements the interface tgb.Handler:
type MyHandler struct {}

func (h *MyHandler) Handle(ctx context.Context, update *tgb.Update) error {
  if update.Message != nil {
    return nil
  }

 log.Printf("update id: %d, message id: %d", update.ID, update.Message.ID)

 return nil
}
  1. Wrap the function to the type tgb.HandlerFunc:
var handler tgb.Handler = tgb.HandlerFunc(func(ctx context.Context, update *tgb.Update) error {
 // skip updates of other types
 if update.Message == nil {
  return nil
 }

 log.Printf("update id: %d, message id: %d", update.ID, update.Message.ID)

 return nil
})
  1. Wrap the function to the type tgb.*Handler for creating typed handlers with null pointer check:
// that handler will be called only for messages
// other updates will be ignored
var handler tgb.Handler = tgb.MessageHandler(func(ctx context.Context, mu *tgb.MessageUpdate) error {
  log.Printf("update id: %d, message id: %d", mu.Update.ID, mu.ID)
  return nil
})

Typed Handlers

For each subtype (field) of tg.Update you can create a typed handler.

Typed handlers it's not about routing updates but about handling them. These handlers will only be called for updates of a certain type, the rest will be skipped. Also, they implement the tgb.Handler interface.

List of typed handlers:

tgb.*Updates has many useful methods for "answer" the update, please checkout godoc by links above.

Receive updates via Polling

Use tgb.NewPoller to create a poller with specified tg.Client and tgb.Handler. Also accepts tgb.PollerOption for customizing the poller.

handler := tgb.HandlerFunc(func(ctx context.Context, update *tgb.Update) error {
  // ...
})

poller := tgb.NewPoller(handler, client,
  // recieve max 100 updates in a batch
  tgb.WithPollerLimit(100),
)

// polling will be stopped on context cancel
if err := poller.Run(ctx); err != nil {
  return err
}

Receive updates via Webhook

Webhook handler and server can be created by tgb.NewWebhook. That function has following arguments:

Webhook has several security checks that are enabled by default:

ℹ️ That checks can be disabled by passing tgb.WithWebhookSecurityToken(""), tgb.WithWebhookSecuritySubnets() when creating the webhook.

⚠️ At the moment, the webhook does not integrate custom certificate. So, you should handle HTTPS requests on load balancer.

handler := tgb.HandlerFunc(func(ctx context.Context, update *tgb.Update) error {
   // ...
})


webhook := tgb.NewWebhook(handler, client, "https://bot.com/webhook",
  tgb.WithDropPendingUpdates(true),
)

// configure telegram webhook and start HTTP server.
// the server will be stopped on context cancel.
if err := webhook.Run(ctx, ":8080"); err != nil {
  return err
}

Webhook is a regular http.Handler that can be used in any HTTP-compatible router. But you should call Webhook.Setup before starting the server to configure the webhook on the Telegram side.

e.g. integration with chi router

handler := tgb.HandlerFunc(func(ctx context.Context, update *tgb.Update) error {
  // ...
})

webhook := tgb.NewWebhook(handler, client, "https://bot.com/webhook",
  tgb.WithDropPendingUpdates(true),
)

// get current webhook configuration and sync it if needed.
if err := webhook.Setup(ctx); err != nil {
  return err
}

r := chi.NewRouter()

r.Get("/webhook", webhook)

http.ListenAndServe(":8080", r)

Routing updates

When building complex bots, routing updates is one of the most boilerplate parts of the code. The tgb package contains a number of primitives to simplify this.

tgb.Router

This is an implementation of tgb.Handler, which provides the ability to route updates between multiple related handlers. It is useful for handling updates in different ways depending on the update subtype.

router := tgb.NewRouter()

router.Message(func(ctx context.Context, mu *tgb.MessageUpdate) error {
  // will be called for every Update with not nil `Message` field
})

router.EditedMessage(func(ctx context.Context, mu *tgb.MessageUpdate) error {
  // will be called for every Update with not nil `EditedMessage` field
})

router.CallbackQuery(func(ctx context.Context, update *tgb.CallbackQueryUpdate) error {
  // will be called for every Update with not nil `CallbackQuery` field
})

client := tg.NewClient(...)

// e.g. run in long polling mode
if err := tgb.NewPoller(router, client).Run(ctx); err != nil {
  return err
}

tgb.Filter

Routing by update subtype is first level of the routing. Second is filters. Filters are needed to determine more precisely which handler to call, for which update, depending on its contents.

In essence, filters are predicates. Functions that return a boolean value. If the value is true, then the given update corresponds to a handler and the handler will be called. If the value is false, check the subsequent handlers.

The tgb package contains many built-in filters.

e.g. command filter (can be customized via CommandFilterOption)

router.Message(func(ctx context.Context, mu *tgb.MessageUpdate) error {
  // will be called for every Update with not nil `Message` field and if the message text contains "/start"
}, tgb.Command("start", ))

The handler registration function accepts any number of filters. They will be combined using the boolean operator and

e.g. handle /start command in private chats only

router.Message(func(ctx context.Context, mu *tgb.MessageUpdate) error {
  // will be called for every Update with not nil `Message` field
  //  and
  // if the message text contains "/start"
  //  and
  // if the Message.Chat.Type is private
}, tgb.Command("start"), tgb.ChatType(tg.ChatTypePrivate))

Logical operator or also supported.

e.g. handle /start command in groups or supergroups only

isGroupOrSupergroup := tgb.Any(
  tgb.ChatType(tg.ChatTypeGroup),
  tgb.ChatType(tg.ChatTypeSupergroup),
)

router.Message(func(ctx context.Context, mu *tgb.MessageUpdate) error {
  // will be called for every Update with not nil `Message` field
  //  and
  // if the message text contains "/start"
  //  and
  //    if the Message.Chat.Type is group
  //      or
  //    if the Message.Chat.Type is supergroup
}, tgb.Command("start"), isGroupOrSupergroup)

All filters are universal. e.g. the command filter can be used in the Message, EditedMessage, ChannelPost, EditedChannelPost handlers. Please checkout tgb.Filter constructors for more information about built-in filters.

For define a custom filter you should implement the tgb.Filter interface. Also you can use tgb.FilterFunc wrapper to define a filter in functional way.

e.g. filter for messages with document attachments with image type

// tgb.All works like boolean `and` operator.
var isDocumentPhoto = tgb.All(
  tgb.MessageType(tg.MessageTypeDocument),
  tgb.FilterFunc(func(ctx context.Context, update *tgb.Update) (bool, error) {
    return strings.HasPrefix(update.Message.Document.MIMEType, "image/"), nil
  }),
)

tgb.Middleware

Middleware is used to modify or process the Update before it is passed to the handler. All middleware should be registered before the handlers registration.

e.g. log all updates

router.Use(func(next tgb.Handler) tgb.Handler {
  return tgb.HandlerFunc(func(ctx context.Context, update *tgb.Update) error {
    defer func(started time.Time) {
      log.Printf("%#v [%s]", update, time.Since(started))
    }(time.Now())

    return next(ctx, update)
  })
})

Error Handler

As you all handlers returns an error. If any error occurs in the chain, it will be passed to that handler. By default, errors are returned back by handler method. You can customize this behavior by passing a custom error handler.

e.g. log all errors

router.Error(func(ctx context.Context, update *tgb.Update, err error) error {
  log.Printf("error when handling update #%d: %v", update.ID, err)
  return nil
})

That example is not useful and just demonstrates the error handler. The better way to achieve this is simply to enable logging in Webhook or Poller.

Extensions

Sessions

What is a Session?

Session it's a simple storage for data related to the Telegram chat. It allow you to share data between different updates from the same chat. This data is persisted in the session store and will be available for the next updates from the same chat.

In fact, the session is the usual struct and you can define it as you wish. One requirement is that the session must be serializable. By default, the session is serialized using encoding/json package, but you can use any other marshal/unmarshal funcs.

When not to use sessions?

Where sessions store

Session store is simple key-value storage. Where key is a string value unique for each chat and value is serialized session data. By default, manager use StoreMemory implementation. Also package has StoreFile based on FS.

How to use sessions?

  1. You should define a session struct: 
     type Session struct {
   PizzaCount int
 }
  2. Create a session manager: 
     var sessionManager = session.NewManager(Session{
   PizzaCount: 0,
 })
  3. Attach the session manager to the router: 
     router.Use(sessionManager)
  4. Use the session manager in the handlers: 
     router.Message(func(ctx context.Context, mu *tgb.Update) error {
   count := strings.Count(strings.ToLower(mu.Message.Text), "pizza") + strings.Count(mu.Message.Text, "🍕")
   if count > 0 {
     session := sessionManager.Get(ctx)
     session.PizzaCount += count
   }
   return nil
 })

See session package and examples with Session Manager feature for more information.

Related Projects

Projects using this package

Thanks