88 lines
3.0 KiB
Markdown
88 lines
3.0 KiB
Markdown
# Uploading Files
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To make files work as expected, there's a lot going on behind the scenes. Make
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sure to read through the [Files](../getting-started/files.md) section in
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Getting Started first as we'll be building on that information.
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This section only talks about file uploading. For non-uploaded files such as
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URLs and file IDs, you just need to pass a string.
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## Fields
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Let's start by talking about how the library represents files as part of a
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Config.
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### Static Fields
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Most endpoints use static file fields. For example, `sendPhoto` expects a single
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file named `photo`. All we have to do is set that single field with the correct
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value (either a string or multipart file). Methods like `sendDocument` take two
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file uploads, a `document` and a `thumb`. These are pretty straightforward.
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Remembering that the `Fileable` interface only requires one method, let's
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implement it for `DocumentConfig`.
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```go
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func (config DocumentConfig) files() []RequestFile {
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// We can have multiple files, so we'll create an array. We also know that
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// there always is a document file, so initialize the array with that.
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files := []RequestFile{{
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Name: "document",
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Data: config.File,
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}}
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// We'll only add a file if we have one.
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if config.Thumb != nil {
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files = append(files, RequestFile{
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Name: "thumb",
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Data: config.Thumb,
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})
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}
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return files
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}
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```
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Telegram also supports the `attach://` syntax (discussed more later) for
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thumbnails, but there's no reason to make things more complicated.
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### Dynamic Fields
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Of course, not everything can be so simple. Methods like `sendMediaGroup`
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can accept many files, and each file can have custom markup. Using a static
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field isn't possible because we need to specify which field is attached to each
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item. Telegram introduced the `attach://` syntax for this.
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Let's follow through creating a new media group with string and file uploads.
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First, we start by creating some `InputMediaPhoto`.
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```go
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photo := tgbotapi.NewInputMediaPhoto(tgbotapi.FilePath("tests/image.jpg"))
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url := tgbotapi.NewInputMediaPhoto(tgbotapi.FileURL("https://i.imgur.com/unQLJIb.jpg"))
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```
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This created a new `InputMediaPhoto` struct, with a type of `photo` and the
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media interface that we specified.
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We'll now create our media group with the photo and URL.
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```go
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mediaGroup := NewMediaGroup(ChatID, []interface{}{
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photo,
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url,
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})
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```
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A `MediaGroupConfig` stores all of the media in an array of interfaces. We now
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have all of the data we need to upload, but how do we figure out field names for
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uploads? We didn't specify `attach://unique-file` anywhere.
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When the library goes to upload the files, it looks at the `params` and `files`
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for the Config. The params are generated by transforming the file into a value
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more suitable for uploading, file IDs and URLs are untouched but uploaded types
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are all changed into `attach://file-%d`. When collecting a list of files to
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upload, it names them the same way. This creates a nearly transparent way of
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handling multiple files in the background without the user having to consider
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what's going on.
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