Confused on how Cache & HTTP interact

[thetayloredman]

The following code fails with "Guild not found in the cache"...

    if command == "config" {
        if !msg
            .member(&ctx.http)
            .await?
            .permissions(&ctx.cache)?
            .manage_guild()
        {
            msg.reply(
                &ctx.http,
                "You need the Manage Server permission to run this command!",
            )
            .await?;
            return Ok(());
        }

How do I do this such that the member is fetched only if they're not cached? Similar to some sort of Discord.js code (await message.member.fetch()).permissions

[arqunis]

Message::member accepts a parameter that implements CacheHttp, or in other words, a type that can provide access to the http client and/or cache. This trait is used wherever a function needs the http client, but may optionally use the cache first if it is given one. Right now, by passing &ctx.http, you're providing Message::member only the http client. You want to pass a reference to the Context instead: msg.member(ctx) (assuming ctx is &Context), as the Context stores both the http client and cache. This way, Message::member will try searching the cache for the message author's member data first before attempting a http request.

...that's not your problem, though. Your error originates from Member::permissions. That function needs the Guild data to calculate the member's permissions, but it's currently failing as the Guild the member is in hasn't been cached yet. What gateway intents have you enabled? Do you at least have GatewayIntents::GUILDS?

[thetayloredman]

I was unaware that ctx was supposed to be used like that. And it sure was the intents at fault. Sorry for the stupid question!