Add file type filtering in slash command attachment options and modal attachment uploads

[freya022]

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Changes

• Internal code
• Library interface (affecting end-user code)
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• Other: _____

Closes Issue: NaN

Description

This PR enables slash commands options, and modal attachment uploads, to accept attachments with specific extensions or media type (image, video, audio ; the list of extensions implied by these is not documented on purpose).

Docs PR: discord/discord-api-docs#8506
Changelog: https://docs.discord.com/developers/change-log#filter-file-types-in-file-uploads-and-attachment-options

Examples

Slash commands

jda.updateCommands()
   .addCommands(
       // Accepts any kind of video and audio supported by Discord
       Commands.slash("merge", "Merge video and audio")
               .addOptions(
                   new OptionData(OptionType.ATTACHMENT, "video", "The source video", true)
                           .addFileTypes(FileType.VIDEO),
                   new OptionData(OptionType.ATTACHMENT, "audio", "The audio to merge in", true)
                           .addFileTypes(FileType.AUDIO)
               ),
       // Accepts a single .svg file
       Commands.slash("render", "Renders a SVG file")
               .addOptions(
                   new OptionData(OptionType.ATTACHMENT, "file", "The SVG to render", true)
                           .addFileTypeExtensions("svg")
               )
   )
   .queue();

Modals

The same methods exist on AttachmentUpload.Builder, with the same limit (10) and same behavior.

[MinnDevelopment]

Why this instead of just making it private?

[freya022]

It's used in FileTypesImpl#fromArray where the raw value is passed.

[MinnDevelopment]

Suggested change

	json.optArray("file_types").map(FileTypesImpl::fromArray).orElse(FileTypesImpl.empty());
	json.optArray("file_types").map(FileTypesImpl::fromArray).orElseGet(FileTypesImpl::empty);

[freya022]

I changed it to keep the orElse but replaced the value to be a constant, empty & immutable list.

[MinnDevelopment]

Immutable and unmodifiable view are different implications. Since the unmodifiable list can still change and thus throw exceptions when modified by a different thread.

[freya022]

Even if a view is returned, Command is an immutable object, so the returned list is also immutable since there is no code that can change it, that's why it's documented and annotated as immutable/unmodifiable, and not as a view.

[MinnDevelopment]

So what happens here when fileTypes is still empty (initial state)?

[freya022]

It sends an empty array, which is the same as if the field was absent, accepting any attachment.