Files
go-telegram/api/download.go
T
lukaszraczylo ac7cae8fa7 Initial release of go-telegram
A fully-generated, strongly-typed Go client for the Telegram Bot API.

* 176 methods + 301 types generated from Bot API v10.0
* 1408 auto-generated tests (8 scenarios per method)
* Typed unions throughout — no 'any' in the public surface
* Pluggable HTTP transport and JSON codec (default goccy/go-json)
* Built-in retry middleware honouring Telegram's retry_after
* Generic dispatcher with filters and conversation handlers
* Self-verifying codegen pipeline (regen → audit → emit → run tests)
* 14 example bots covering common patterns
2026-05-09 13:09:27 +01:00

58 lines
1.8 KiB
Go

package api
import (
"context"
"fmt"
"io"
"net/http"
"github.com/lukaszraczylo/go-telegram/client"
)
// DownloadFile fetches the contents of a Telegram-hosted file given a
// previously-uploaded file_id. It calls GetFile to resolve the file's
// download path, then issues an HTTP GET to the file CDN endpoint.
//
// The returned io.ReadCloser must be closed by the caller. The size of
// the file is reported via *File.FileSize when known.
//
// For files larger than 20 MB, Telegram requires a self-hosted Bot API
// server (default api.telegram.org has a 20 MB limit on getFile).
func DownloadFile(ctx context.Context, b *client.Bot, fileID string) (io.ReadCloser, *File, error) {
f, err := GetFile(ctx, b, &GetFileParams{FileID: fileID})
if err != nil {
return nil, nil, fmt.Errorf("getFile: %w", err)
}
if f == nil || f.FilePath == "" {
return nil, f, fmt.Errorf("telegram: file %q has no download path", fileID)
}
rc, err := DownloadFileByPath(ctx, b, f.FilePath)
if err != nil {
return nil, f, err
}
return rc, f, nil
}
// DownloadFileByPath fetches a file by its file_path (typically obtained
// from a prior File response). Useful when the caller already has a
// *File and wants to skip the GetFile round-trip.
func DownloadFileByPath(ctx context.Context, b *client.Bot, filePath string) (io.ReadCloser, error) {
url := fmt.Sprintf("%s/file/bot%s/%s", b.BaseURL(), b.Token(), filePath)
req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
if err != nil {
return nil, err
}
resp, err := b.HTTP().Do(req)
if err != nil {
if ctxErr := ctx.Err(); ctxErr != nil {
return nil, ctxErr
}
return nil, fmt.Errorf("download: %w", err)
}
if resp.StatusCode != http.StatusOK {
_ = resp.Body.Close()
return nil, fmt.Errorf("download: HTTP %d", resp.StatusCode)
}
return resp.Body, nil
}