tgbotapi/tgbotapi.core/README.md

TelegramBotAPI Core

What is it?

Library for Object-Oriented and type-safe work with Telegram Bot API. Most part of some specific solves or unuseful moments are describing by official Telegram Bot API.

How to implement library?

Common ways to implement this library are presented here. In some cases it will require additional steps like inserting of additional libraries (like kotlin stdlib). In the examples will be used variable telegrambotapi.version, which must be set up by developer. Available versions are presented on maven central, next version is last published:

Currently, last versions of library can be available from the Maven repository with errors (for the reason difficult in publishing of signed artifacts in Bintray). You can:

• Use earlier version (available version you can find here (before 0.28.0) or here)
• Add mavenCentral repository in build config

Maven

Dependency config presented here:

<dependency>
  <groupId>dev.inmo</groupId>
  <artifactId>tgbotapi.core</artifactId>
  <version>${telegrambotapi.version}</version>
</dependency>

Gradle

To use last versions you will need to add one line in repositories block of your build.gradle:

mavenCentral()

And add next line to your dependencies block:

implementation "dev.inmo:tgbotapi.core:$telegrambotapi_version"

or for old gradle:

compile "dev.inmo:tgbotapi.core:$telegrambotapi_version"

How to work with library?

For now, this library have no some API god-object. Instead of this, this library has several important objects:

• RequestsExecutor
• Requests
• Types

Types

Types declare different objects representation. For example, Chat for now represented as interface and has several realisations:

• PrivateChat
• GroupChat
• SupergroupChat
• ChannelChat

Instead of common garbage with all information as in original Chat, here it was separated for more obvious difference between chats types and their possible content.

The same principle work with a lot of others things in this Telegram bot API.

Requests

Requests usually are very simple objects, but some of them are using their own build factories. For example, the next code show, how to get information about bot:

val requestsExecutor: RequestsExecutor = ...
requestsExecutor.execute(GetMe())

Also there is an alternative syntax for requests (like requestsExecutor.getMe() in project tgbotapi.api)

The result type of GetMe (and getMe extension) request is ExtendedBot.

RequestsExecutor

It is base object which can be used to execute requests in API. For now by default included Ktor realisation of RequestsExecutor, but it is possible, that in future it will be extracted in separated project. How to create RequestsExecutor:

val requestsExecutor = KtorRequestsExecutor(
    TelegramAPIUrlsKeeper(TOKEN)
)

Here:

• KtorRequestsExecutor - default realisation with ktor
• TelegramAPIUrlsKeeper - special keeper, which you can save and use for getting files full urls (resolveFileURL extension inside of PathedFile.kt)
• TOKEN is just a token of bot which was retrieved according to instruction.

By default, for JVM there is implemented CIO client engine, but there is not server engine. Both can be changed like here:

dependencies {
    // ...
    implementation "io.ktor:ktor-server-cio:$ktor_version" // for implementing of server engine
    implementation "io.ktor:ktor-client-okhttp:$ktor_version" // for implementing of additional client engine
    // ...
}

You can avoid using of server dependency in case if you will not use Webhooks. In this case, dependencies list will be simplify:

dependencies {
    // ...
    implementation "io.ktor:ktor-client-okhttp:$ktor_version" // for implementing of additional client engine
    // ...
}

Here was used okhttp realisation of client, but there are several others engines for Ktor. More information available on ktor.io site for client and server engines.

Passport

In case you wish to work with Telegram Passport, currently there are several useful things, but most part of working with decryption and handling is available only on JVM. Next snippet contains example of data decryption on JVM platform:

passportMessage.passportData.doInDecryptionContextWithPKCS8Key(privateKey) {
    val passportDataSecureValue = passport ?.data ?: return@doInDecryptionContextWithPKCS8Key
    val passportData = (passportMessage.passportData.data.firstOrNull { it is CommonPassport } ?: return@doInDecryptionContextWithPKCS8Key) as CommonPassport
    val decrypted = passportDataSecureValue.decrypt(
        passportData.data
    ) ?.decodeToString() ?: return@doInDecryptionContextWithPKCS8Key
    println(decrypted)
}