Thread names get exported as `#deleted-channel` in mentions

[ShadowJonathan]

Version

2.43.3

Flavor

CLI (Command-Line Interface)

Platform

Linux (Debian)

Export format

HTML

Steps to reproduce

• Make a mention to a thread in a channel
• Export that channel
• Observe the mention being converted to #deleted-channel

Details

This piece of code is relevant;

DiscordChatExporter/DiscordChatExporter.Core/Exporting/HtmlMarkdownVisitor.cs

Line 284 in 281e0f6

var name = channel?.Name ?? "deleted-channel";

It only looks for a name of the channel, not of a thread.

Even discord seems to struggle, not fetching a corresponding thread, only saying #unknown

Checklist

• I have looked through existing issues to make sure that this bug has not been reported before
• I have provided a descriptive title for this issue
• I have made sure that this bug is reproducible on the latest version of the application
• I have provided all the information needed to reproduce this bug as efficiently as possible
• I have sponsored this project
• I have not read any of the above and just checked all the boxes to submit the issue

[Tyrrrz]

The issue is that we don't preload all threads as we do with channels, so we can't resolve the mentions the same way:

DiscordChatExporter/DiscordChatExporter.Core/Exporting/ExportContext.cs

Lines 34 to 49 in 281e0f6

	public async ValueTask PopulateChannelsAndRolesAsync(
	CancellationToken cancellationToken = default
	)
	{
	await foreach (
	var channel in Discord.GetGuildChannelsAsync(Request.Guild.Id, cancellationToken)
	)
	{
	_channelsById[channel.Id] = channel;
	}
	await foreach (var role in Discord.GetGuildRolesAsync(Request.Guild.Id, cancellationToken))
	{
	_rolesById[role.Id] = role;
	}
	}

We should employ a strategy similar to members:

DiscordChatExporter/DiscordChatExporter.Core/Exporting/ExportContext.cs

Lines 51 to 86 in 281e0f6

	// Because members cannot be pulled in bulk, we need to populate them on demand
	private async ValueTask PopulateMemberAsync(
	Snowflake id,
	User? fallbackUser,
	CancellationToken cancellationToken = default
	)
	{
	if (_membersById.ContainsKey(id))
	return;
	var member = await Discord.TryGetGuildMemberAsync(Request.Guild.Id, id, cancellationToken);
	// User may have left the guild since they were mentioned.
	// Create a dummy member object based on the user info.
	if (member is null)
	{
	var user = fallbackUser ?? await Discord.TryGetUserAsync(id, cancellationToken);
	// User may have been deleted since they were mentioned
	if (user is not null)
	member = Member.CreateFallback(user);
	}
	// Store the result even if it's null, to avoid re-fetching non-existing members
	_membersById[id] = member;
	}
	public async ValueTask PopulateMemberAsync(
	Snowflake id,
	CancellationToken cancellationToken = default
	) => await PopulateMemberAsync(id, null, cancellationToken);
	public async ValueTask PopulateMemberAsync(
	User user,
	CancellationToken cancellationToken = default
	) => await PopulateMemberAsync(user.Id, user, cancellationToken);

However, fetching threads can be very slow so we probably shouldn't do that too prematurely either.