Fetch channel when not found upon converting message

[shtlrs]

Summary

Fetch channel upon message converion

What is the feature request for?

discord.ext.commands

The Problem

Currently, here's how the MessageConverter works

If the message trying to be converted is found, return directly
Otherwise, try to resolve the channel from the bot's cache.
If the channel isn't found, throw a ChannelNotFound exception

 async def convert(self, ctx: Context[BotT], argument: str) -> discord.Message:
        guild_id, message_id, channel_id = PartialMessageConverter._get_id_matches(ctx, argument)
        message = ctx.bot._connection._get_message(message_id)
        if message:
            return message
        channel = PartialMessageConverter._resolve_channel(ctx, guild_id, channel_id)
        if not channel or not isinstance(channel, discord.abc.Messageable):
            raise ChannelNotFound(channel_id)
        try:
            return await channel.fetch_message(message_id)
        except discord.NotFound:
            raise MessageNotFound(argument)
        except discord.Forbidden:
            raise ChannelNotReadable(channel)  # type: ignore # type-checker thinks channel could be a DMChannel at this point

The problem here is that it tries to fetch the message if not found, but not the channel, which results in never being able to convert the message.

The Ideal Solution

Ideal solution would be to try to fetch the channel if it's not in cache, then (maybe) cache it again for future usages.
Which would result in something like

 async def convert(self, ctx: Context[BotT], argument: str) -> discord.Message:
        guild_id, message_id, channel_id = PartialMessageConverter._get_id_matches(ctx, argument)
        message = ctx.bot._connection._get_message(message_id)
        if message:
            return message
        channel = PartialMessageConverter._resolve_channel(ctx, guild_id, channel_id) or bot.fetch_channel(channel_id)
        if not channel or not isinstance(channel, discord.abc.Messageable):
            raise ChannelNotFound(channel_id)
        try:
            return await channel.fetch_message(message_id)
        except discord.NotFound:
            raise MessageNotFound(argument)
        except discord.Forbidden:
            raise ChannelNotReadable(channel)  # type: ignore # type-checker thinks channel could be a DMChannel at this point

The Current Solution

No response

Additional Context

No response

[Rapptz]

It's not this way on purpose so you don't get bombarded with (another) bogus 400 requests when someone crafts either a garbage URL with an obviously wrong ID or a message ID you can't read to begin with. This change would cause the invalid requests on the worst case to go from one 400 to two.

There is a PartialMessageable type now that could be used but it'd need some work in order to make ChannelNotFound viable.

[shtlrs]

It's not this way on purpose so you don't get bombarded with (another) bogus 400 requests when someone crafts either a garbage URL with an obviously wrong ID or a message ID you can't read to begin with. This change would cause the invalid requests on the worst case to go from one 400 to two.

There is a PartialMessageable type now that could be used but it'd need some work in order to make ChannelNotFound viable.

Hum, I see.

But leveraging a PartialMessage wouldn't really solve the issue in the MessageConverter, or am I missing something ?

I guess this would need to be done client-side once, then that can be cached along with the rest to avoid recurrent requests.

[Rapptz]

Not PartialMessage, PartialMessageable. The latter is a partial channel type where messages can be sent.