@grammyjs/types

Telegram Bot API types for grammY

grammY makes writing Telegram bots easy. Check it out!

This package just provides type annotations for the complete Telegram Bot API, and applies various transformations to make them usable for grammY. It contains no runnable code.

Originally, this package is based on typegram, but since the update to Telegram Bot API 5.1, typegram is no longer directly updated. Instead, this package is maintained and its updates are backported to typegram. Hence, both packages are kept up to date with the Telegram Bot API for now.

Available Types

Generally this package just exposes a huge load of interfaces that correspond to the types used throughout the Telegram Bot API.

Note that the API specification sometimes only has one name for multiple variants of a type, e.g. there is a number of different Updates you can receive, but they're all just called Update. This package represents such types as large unions of all possible options of what an Update could be, such that type narrowing can work as expected on your side. If you need to access the individual variants of an Update, refer to Update.MessageUpdate and its siblings.

In fact, this pattern is used for various types, namely:

• CallbackQuery
• Chat
• ChatFromGetChat
• InlineKeyboardButton
• KeyboardButton
• Message
• MessageEntity
• Location
• Update

The union types are not exposed as-is. Instead, they are closed first. Read the section about type transformations to learn what closed types are for grammY.

Naturally, when the API specification is actually modelling types to be unions (e.g. InlineQueryResult), this is reflected here as a union type, too. Those types are not closed.

Available Methods

In addition to the types, this package provides you with another type Telegram which contains all available methods of the API. There is no further structure applied to this, but if you can come up with something reasonable, please suggest it in an issue or directly open a PR. In grammY, these types are what defines the bot.api.raw object.

Each method takes just a single argument with a structure that corresponds to the object expected by Telegram. The helper type Opts<M> (where M is the method name) allows grammY to access that type directly.

Handling JSON-Serialized Objects

Some methods of the Telegram Bot API are expected to be called with JSON-serialized objects contained in a property of the payload, rather than an actual JSON payload. In other words, the objects are serialized twice—the first time in order to conform with the docs, and the second time when the payload is actually sent in the POST body to the API server.

The most prominent example is the reply_markup property that appears in a number of different methods, but more than a dozen other properties like this can be found throughout the API.

Strictly speaking, the @grammyjs/types types do not reflect this accurately. Instead of using string (representing a serialized object) as the type, @grammyjs/types uses the type of the object itself, thus ignoring the serialization step. For instance, instead of declaring reply_markup: string, it declares the property as reply_markup: InlineKeyboardMarkup | ReplyKeyboardMarkup | ReplyKeyboardRemove | ForceReply because that is what is supposed to be serialized to string before calling the respective method.

That makes sense for the reason that grammY uses the types in its wrapper code around the Telegram Bot API, exposed as bot.raw.api. This wrapper code does the necessary JSON serialization automatically for the required properties. Bots written with grammY then do not need to care about which properties to serialize and which not. Given that @grammyjs/types refers to the objects themselves instead of their serialized strings, the wrapper code can now simply expose the @grammyjs/types types to its consumers without having to transform them before.

Customizing InputFile

The Telegram Bot API lets bots send files in three different ways. Two of those ways are by specifying a string—either a file_id or a URL. The third option, however, is by uploading files to the server using multipart/form-data.

The first two means to send a file are already covered by the type annotations across the library. In all places where a file_id or a URL is permitted, the corresponding property allows a string.

We will now look at the type declarations that are relevant for uploading files directly. grammY automatically translates calls to sendDocument and the like to multipart/form-data uploads when supplied with an InputFile object in the document property of the argument object.

@grammyjs/types should not have to know what objects you want to support as InputFiles. Consequently, the type InputFile is not defined in this library.

Instead, grammY specifies its own version of what an InputFile is, hence automatically adjusting @grammyjs/types with a custom InputFile type used throughout all affected methods and interfaces. This is possible by what we call a proxy type. grammY then imports the proxy type called InputProxyType and parametrises it with its version of InputFile.