How to make a Roblox script search a player's backpack - roblox

Question

I am trying to make a script that searches a players backpack when they touch a door, so it can tell if the player has a key card. If the player has a key card, it should say "Yes", but for some reason it keeps bringing up an error. Here is my code:
function onTouched(m)
p = m.Parent:findFirstChild("Humanoid")
if p ~= nil then
n = p.parent
local letin = game.Players(n).Backpack:FindFirstChild("Key Card")
if letin then
print("Yes")
else
print("No")
end
end
end
script.Parent.Touched:connect(onTouched)
The error is:
Trying to call method on object of type: 'Player' with incorrect arguments.
Does anyone know why this might not work?

Answer 1

I think you've got two problems :
It looks like you are trying to access an array index, but you're using () instead of [].
The game.Players object is a service class, not an array. But you can call game.Players:GetPlayers() to get that array of the players.
Since you are already getting the player object, you can simply grab the player's name and use that to lookup the player from game.Players.
Your script just about works, here's a fix for you :
function onTouched(m)
-- get the player in game that touched the thing
local p = m.Parent:findFirstChild("Humanoid")
if p ~= nil then
-- grab the player's name
local n = p.parent.Name
-- find the player in the player list, escape if something goes wrong
local player = game.Players:FindFirstChild(n, false)
if player == nil then
return
end
-- search the player's backpack for the keycard
local keycard = player.Backpack:FindFirstChild("Key Card")
if keycard then
print("Yes")
else
print("No")
end
end
end
script.Parent.Touched:connect(onTouched)

Answer 2

The following line of code is incorrect, because instead of finding a child in
'game.Players', you call it as a function by using parenthesis.
local letin = game.Players(n).Backpack:FindFirstChild("Key Card")
What you probably intended was:
local letin = game.Players[n].Backpack:FindFirstChild("Key Card")
A more clean approach to getting that 'Key Card' is to also check if 'n' really is the name of a player, rather than that of a NPC.
local player = game.Players:FindFirstChild(n)
if player then
local letin = player.Backpack:FindFirstChild("Key Card")
print(letin)
end