Telegram bots with Kotlin

Telegram Bots are third-party applications that run inside Telegram. Users can interact with bots by sending them messages, commands and inline requests. The bots are controlled using HTTPS requests to Telegram's bot API.

We can create bots to get customized notifications and news, integrate with other services, accept payments from Telegram users, create custom tools, build games and social services and do virtually anything else.

In this talk we will deep into details about how we can start creating these awesome bots and all the possibilities we have with them. Moreover, we will work with one of the programming languages of the moment, Kotlin, that will let us creating these bots in a really easy and elegant way.

Transcript

1. Telegram Bots with Kotlin Víctor J. García Granado @vjgg96
2. What’s Telegram?
3. What’s Telegram? >>>
4. What’s a Telegram bot?
5. What can I do with Telegram Bots?
6. What can I do with Telegram Bots? • Get customized notifications and news (NewsBot)
7. What can I do with Telegram Bots? • Get customized notifications and news (NewsBot) • Integrate with other services (GIFBot)
8. What can I do with Telegram Bots? • Get customized notifications and news (NewsBot) • Integrate with other services (GIFBot) • Accept payments from Telegram users (InviteMember)
9. What can I do with Telegram Bots? • Get customized notifications and news (NewsBot) • Integrate with other services (GIFBot) • Accept payments from Telegram users (InviteMember) • Build games (GameBot)
10. What can I do with Telegram Bots? • Get customized notifications and news (NewsBot) • Integrate with other services (GIFBot) • Accept payments from Telegram users (InviteMember) • Build games (GameBot) • Whatever you want...
11. How do bots work?
12. How do bots work? • At the core, Telegram Bots are special accounts that do not require an additional phone number to set up
13. How do bots work? • At the core, Telegram Bots are special accounts that do not require an additional phone number to set up • Messages, commands and requests sent by users are passed to the software running on our servers
14. Telegram servers Telegram intermediary servers Our bot server bot api operations operations /updates bot updates Telegram clients
15. Telegram servers Telegram intermediary servers Our bot server bot api operations operations /updates bot updates Telegram clients BOT API
16. How do I create a bot?
17. How do I create a bot? 976951878:AAETlyNbC0ocEilDjq09hMDQf8uLXw3qw6A https://t.me/MySampleBot
18. Making requests to bot API https://api.telegram.org/bot<token>/METHOD_NAME • GET and POST HTTP methods • Four ways of passing parameters ◦ Query params ◦ application/x-www-form-urlencoded ◦ application/json (except for uploading files) ◦ application/form-data (for uploading file)
19. Bot API responses { "ok": true, "result": [] } { "ok": false, "error_code": 401, "description": "Unauthorized" }
20. Listening to user updates • There are two ways of receiving updates for a bot: ◦ getUpdates API method -> Long polling ◦ setWebhook API method -> Webhook • They are mutually exclusive
21. { "ok": true, "result": [ { "update_id": 911858287, "message": { "message_id": 20, "from": { "id": 187395179, "is_bot": false, "first_name": "Victor J", "last_name": "Garcia Granado", "username": "vjgarciag96", "language_code": "en" }, "chat": { "id": 187395179, "first_name": "Victor J", "last_name": "Garcia Granado", "username": "vjgarciag96", "type": "private" }, "date": 1572202802, "text": "hehehe" } }, ... ] }
22. Other operations • sendMessage • sendPhoto • getFile • answerInlineQuery • sendGame • kickChatMember • etc...
23. Let’s create our first bot
24. Let’s create our first bot • Say something when /padrino command is received
27. • Say something when /padrino command is received • Answer inline queries with Github repos search results Let’s create our first bot
32. https://github.com/pengrad/java-telegram-bot-api
34. Say something when /padrino command is received
35. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDjq0...");
36. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDjq0..."); telegramBot.setUpdatesListener(updates -> { });
37. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDjq0..."); telegramBot.setUpdatesListener(updates -> { return UpdatesListener.CONFIRMED_UPDATES_ALL; });
38. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDj..."); telegramBot.setUpdatesListener(updates -> { updates.forEach(update -> { if (update.message() != null && update.message().text() != null && update.message().text().equals("/padrino")) { } }); return UpdatesListener.CONFIRMED_UPDATES_ALL; });
39. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDj..."); telegramBot.setUpdatesListener(updates -> { updates.forEach(update -> { if (update.message() != null && update.message().text() != null && update.message().text().equals("/padrino")) { long chatId = update.message().chat().id(); telegramBot.execute(new SendMessage(chatId, "Algún día, y ...")); } }); return UpdatesListener.CONFIRMED_UPDATES_ALL; });
40. Answer inline queries with Github repos search results
41. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDj..."); telegramBot.setUpdatesListener(updates -> { updates.forEach(update -> { if (update.message() != null && update.message().text() != null && update.message().text().equals("/padrino")) { long chatId = update.message().chat().id(); telegramBot.execute(new SendMessage(chatId, "Algún día, y ...")); } }); return UpdatesListener.CONFIRMED_UPDATES_ALL; });
42. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDj..."); telegramBot.setUpdatesListener(updates -> { updates.forEach(update -> { if (update.message() != null && update.message().text() != null && update.message().text().equals("/padrino")) { sayHi(telegramBot, update.message()); return; } if (update.inlineQuery() != null) { showGithubReposSearchResult(telegramBot, update.inlineQuery()); return; } }); return UpdatesListener.CONFIRMED_UPDATES_ALL; });
43. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { }
44. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { String queryText = inlineQuery.query(); }
45. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { String queryText = inlineQuery.query(); if (queryText.trim().isEmpty()) return; }
46. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { String queryText = inlineQuery.query(); if (queryText.trim().isEmpty()) return; GithubApi.search(queryText, githubRepos -> { }); }
47. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { String queryText = inlineQuery.query(); if (queryText.trim().isEmpty()) return; GithubApi.search(queryText, githubRepos -> { List<InlineQueryResultArticle> queryResults = githubRepos.stream() .map(repo -> ) .collect(Collectors.toList()); }); }
48. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { String queryText = inlineQuery.query(); if (queryText.trim().isEmpty()) return; GithubApi.search(queryText, githubRepos -> { List<InlineQueryResultArticle> queryResults = githubRepos.stream() .map(repo -> new InlineQueryResultArticle(UUID.randomUUID().toString(), repo.getName(), repo.getDescription(), repo.getOwner().getAvatarUrl(), new InputTextMessageContent(repo.getUrl())) .collect(Collectors.toList()); }); }
49. private static void showGithubReposSearchResults(TelegramBot telegramBot, InlineQuery inlineQuery) { String queryText = inlineQuery.query(); if (queryText.trim().isEmpty()) return; GithubApi.search(queryText, githubRepos -> { List<InlineQueryResultArticle> queryResults = githubRepos.stream() .map(repo -> new InlineQueryResultArticle(UUID.randomUUID().toString(), repo.getName(), repo.getDescription(), repo.getOwner().getAvatarUrl(), new InputTextMessageContent(repo.getUrl())) .collect(Collectors.toList()); telegramBot.execute(new AnswerInlineQuery(inlineQuery.id(), queryResults))); }); }
51. What’s Kotlin?
52. What’s Kotlin? >>>
53. • Null safety • Immutability • Functions as first-class citizens • Extension functions • Data classes • Sealed classes • Java interoperability • DSLs • etc...
54. DSLs
55. fun aFun(anotherFun: () -> Unit) { anotherFun() } • Use of lambdas outside of function parentheses
56. fun aFun(anotherFun: () -> Unit) { anotherFun() } aFun({println("HelloWorld!!")}) • Use of lambdas outside of function parentheses
57. fun aFun(anotherFun: () -> Unit) { anotherFun() } aFun({println("HelloWorld!!")}) aFun {println("HelloWorld!!")} • Use of lambdas outside of function parentheses
58. • Use of lambdas outside of function parentheses • Extension functions fun String.isBlankOrEmpty() = isBlank() or isEmpty()
59. • Use of lambdas outside of function parentheses • Extension functions • Lambdas with receivers fun aFun(anotherFun: String.() -> Unit) { "Hello-World-!!".anotherFun() }
60. • Use of lambdas outside of function parentheses • Extension functions • Lambdas with receivers fun aFun(anotherFun: String.() -> Unit) { "Hello-World-!!".anotherFun() } aFun { println(split("-").joinToString(" ")) }
61. Kotlin DSLs
62. Kotlin DSLs <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity"> <EditText android:id="@+id/nameInput" android:layout_width="match_parent" android:layout_height="wrap_content" android:inputType="text" /> <Button android:id="@+id/sayHelloButton" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Say Hello" tools:ignore="HardcodedText" /> </LinearLayout>
63. Kotlin DSLs class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) sayHelloButton.setOnClickListener { val name = nameInput.text?.toString() name?.let { Toast.makeText(this, "Hello, $it", Toast.LENGTH_SHORT).show() } } } }
64. Kotlin DSLs verticalLayout { val name = editText() button("Say Hello") { onClick { toast("Hello, ${name.text}!") } } } ANDROID VIEW DSL
65. How do we write a DSL?
66. person { name = "John" age = 25 address { street = "Main Street" number = 42 city = "London" } }
67. data class Person(var name: String? = null, var age: Int? = null, var address: Address? = null) data class Address(var street: String? = null, var number: Int? = null, var city: String? = null)
68. fun person(block: (Person) -> Unit): Person { }
69. fun person(block: (Person) -> Unit): Person { val p = Person() }
70. fun person(block: (Person) -> Unit): Person { val p = Person() block(p) }
71. fun person(block: (Person) -> Unit): Person { val p = Person() block(p) return p }
72. fun person(block: (Person) -> Unit): Person { val p = Person() block(p) return p } person { it.name = "John" it.age = 25 }
73. fun person(block: Person.() -> Unit): Person { val p = Person() p.block() return p }
74. fun person(block: Person.() -> Unit): Person { val p = Person() p.block() return p }
75. fun person(block: Person.() -> Unit): Person { val p = Person() p.block() return p } fun person(block: Person.() -> Unit): Person = Person().apply(block)
76. person { name = "John" age = 25 } fun person(block: Person.() -> Unit): Person { val p = Person() p.block() return p } fun person(block: Person.() -> Unit): Person = Person().apply(block)
77. fun person(block: Person.() -> Unit): Person = Person().apply(block)
78. fun person(block: Person.() -> Unit): Person = Person().apply(block) fun Person.address(block: Address.() -> Unit) { address = Address().apply(block) }
79. fun person(block: Person.() -> Unit): Person = Person().apply(block) fun Person.address(block: Address.() -> Unit) { address = Address().apply(block) } person { name = "John" age = 25 address { street = "Main Street" number = 42 city = "London" } }
80. Say something when /padrino command is received
81. bot("976951878:AAETlyNbC0ocEilDjq09h...") { }
82. bot("976951878:AAETlyNbC0ocEilDjq09h...") { command("padrino") { bot, message -> } }
83. bot("976951878:AAETlyNbC0ocEilDjq09h...") { command("padrino") { bot, message -> bot.sendMessage(message.chat().id(), "Algún día, y ...") } }
84. Answer inline queries with Github repos search results
85. bot("976951878:AAETlyNbC0ocEilD...") { command("padrino") { bot, message -> bot.sendMessage(message.chat().id(), "Algún día, y ...") } }
86. bot("976951878:AAETlyNbC0ocEilD...") { command("padrino") { bot, message -> bot.sendMessage(message.chat().id(), "Algún día, y ...") } inlineQuery { bot, inlineQuery -> bot.showGithubReposSearchResult(inlineQuery) } }
87. private fun Bot.showGithubReposSearchResult(inlineQuery: InlineQuery) { }
88. private fun Bot.showGithubReposSearchResult(inlineQuery: InlineQuery) { val queryText = inlineQuery.query() }
89. private fun Bot.showGithubReposSearchResult(inlineQuery: InlineQuery) { val queryText = inlineQuery.query() if (queryText.isBlankOrEmpty()) return }
90. private fun Bot.showGithubReposSearchResult(inlineQuery: InlineQuery) { val queryText = inlineQuery.query() if (queryText.isBlankOrEmpty()) return GithubApi.search(queryText) { repos -> } }
91. private fun Bot.showGithubReposSearchResult(inlineQuery: InlineQuery) { val queryText = inlineQuery.query() if (queryText.isBlankOrEmpty()) return GithubApi.search(queryText) { repos -> val reposInlineResult = repos.map(GithubRepo::toInlineResult) } } private fun GithubRepo.toInlineResult(): InlineQueryResultArticle = InlineQueryResultArticle( UUID.randomUUID().toString(), name, description, owner.avatarUrl, InputTextMessageContent(url) )
92. private fun Bot.showGithubReposSearchResult(inlineQuery: InlineQuery) { val queryText = inlineQuery.query() if (queryText.isBlankOrEmpty()) return GithubApi.search(queryText) { repos -> val reposInlineResult = repos.map(GithubRepo::toInlineResult) answerInlineQuery(inlineQuery.id(), reposInlineResult) } } private fun GithubRepo.toInlineResult(): InlineQueryResultArticle = InlineQueryResultArticle( UUID.randomUUID().toString(), name, description, owner.avatarUrl, InputTextMessageContent(url) )
93. bot("976951878:AAETlyNbC0ocEilD...") { command("padrino") { bot, message -> bot.sayHi(message.chat().id()) } inlineQuery { bot, inlineQuery -> bot.showGithubReposSearchResult(inlineQuery) } }
94. TelegramBot telegramBot = new TelegramBot("976951878:AAETlyNbC0ocEilDj..."); telegramBot.setUpdatesListener(updates -> { updates.forEach(update -> { if (update.message() != null && update.message().text() != null && update.message().text().equals("/padrino")) { sayHi(telegramBot, update.message()); return; } if (update.inlineQuery() != null) { showGithubReposSearchResults(telegramBot, update.inlineQuery()); return; } }); return UpdatesListener.CONFIRMED_UPDATES_ALL; });
96. Bot DSL http://tiny.cc/zrh6ez
97. What we covered • What’s a Telegram bot?
98. What we covered • What’s a Telegram bot? • What can I do with Telegram Bots?
99. What we covered • What’s a Telegram bot? • What can I do with Telegram Bots? • How do bots works?
100. What we covered • What’s a Telegram bot? • What can I do with Telegram Bots? • How do bots works? • How do I create a bot?
101. What we covered • What’s a Telegram bot? • What can I do with Telegram Bots? • How do bots works? • How do I create a bot? • Bot API
102. What we covered • What’s a Telegram bot? • What can I do with Telegram Bots? • How do bots works? • How do I create a bot? • Bot API • Sample implementation
103. What we covered • What’s a Telegram bot? • What can I do with Telegram Bots? • How do bots works? • How do I create a bot? • Bot API • Sample implementation • Kotlin DSLs
104. Questions
105. Interesting links • https://core.telegram.org/bots/api • https://github.com/vjgarciag96/telegram-bots-with-kotlin • https://github.com/kotlin-telegram-bot/kotlin-telegram-bot