I have found a user-to-ID API. I do not know how to get the ID from it though. The code is as follows.
if (string.find(msg, "!promote") == 1) then --- msg starts with "!promote"
-- words and numbers
for word in msg:gmatch("%w+") do
if word ~= "!promote" then
local p = matchPlayer(word)
userid = game.HttpService:GetAsync("http://api.roblox.com/users/get-by-username?username="..p)
if p ~= nil then
promouser(userid,GROUPID,RANKID)
end
end
end
end
This is what the API would show for my username.
{"Id":39234598,"Username":"Smaltin", "AvatarUri":null,"AvatarFinal":false,"IsOnline":false}
Any help? Thanks!

3 comments
You do not need to do this, you could just use game.Players:GetUserIdFromUsernameAsync() and vice versa
Ok. Could you put a snippet of code, since I am not advanced with this stuff yet?
He did: game.Players:GetUserIdFromUsernameAsync()