Sending a file

There are three ways to send files (photos, stickers, audio, media, etc.):

• If the file is already stored somewhere on the Telegram servers, you don't need to reupload it: each file object has a file_id field, simply pass this file_id as a parameter instead of uploading. There are no limits for files sent this way.
• Provide Telegram with an HTTP URL for the file to be sent. Telegram will download and send the file. 5 MB max size for photos and 20 MB max for other types of content.
• Post the file using multipart/form-data or FormDataBuilder in the usual way that files are uploaded via the browser. 10 MB max size for photos, 50 MB for other files.

Sending by multipart/form-data

• tgx-core provides a FormDataBuilder to attach to a query to send a file.
• Here's an example of sending a photo.

  message.reply(
      MessagePayloadMethod.Photo,
      {
          photo: new File('C:/../../../media/photo.png')
      }
  )

• Here's an example of sending a photo with advanced configuration.

  message.reply(
      MessagePayloadMethod.Photo,
      {
          photo: 'attach://photo_name'
      },
      new FormdataBuilder()
          .append('photo_name', 'C:/../../../media/photo.png', --FormData.AppendOptions)
  )

Sending by file_id

• It is not possible to change the file type when resending by file_id. I.e. a video can't be sent as a photo, a photo can't be sent as a document, etc.
• It is not possible to resend thumbnails.
• Resending a photo by file_id will send all of its sizes.
• file_id is unique for each individual bot and can't be transferred from one bot to another.
• file_id uniquely identifies a file, but a file can have different valid file_ids even for the same bot.

message.reply(MessagePayloadMethod.Photo, {
    photo: '<file_id>'
})

Sending by URL

• When sending by URL the file must have the correct MIME type (e.g., audio/mpeg for sendAudio, etc.).
• In sendDocument, sending by URL will currently only work for GIF, PDF and ZIP files.
• To use sendVoice, the file must have the type audio/ogg and be no more than 1MB in size. 1-20MB voice notes will be sent as files.
• Other configurations may work but we can't guarantee that they will.

Reference

The information was provided by Telegram's bot API documentation, TelegramAPI#sending-files.