Need help understanding Collection Service

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#1

I’m trying to use collection service because I’m trying to make multiple objects

Here is the code that I wrote, I understand most of it but I’m still confused about GetInstanceAddedSignal

local collectionService = game:GetService("CollectionService")

local part = script.Parent 
local yeet = game.Workspace.yeet

collectionService:AddTag(part, "Door")
collectionService:AddTag(yeet, "Door")
	
collectionService:GetInstanceAddedSignal("Door"):Connect(function() this doesn't make sense, isn't this function supposed to give me a signal where if i add a tag this event will run?
	print("yes")
end)

for _,v in pairs(collectionService:GetTagged("Door")) do -- This makes sense it prints the parts that have the door tag 
	print(v)
end

I also have trouble understanding the code on the wiki for collection service

I don’t understand where the tags are being added, I understand the object and the methods but not the bottom part of the script, the collection service part.

local CollectionService = game:GetService("CollectionService")
 
------------------------------------------------------------------------------ 
-- In this section of the script, we define a Door class. This could be placed in
-- its own independent ModuleScript.
 
-- For more information on this class pattern, check out
-- the object-oriented programming chapter in Programming in Lua:  
-- https://www.lua.org/pil/16.html
 
local Door = {}
Door.__index = Door
Door.TAG_NAME = "Door"
Door.OPEN_TIME = 2
 
function Door.new(door)
	-- Create a table which will act as our new door object.
	local self = {}
	-- Setting the metatable allows the table to access
	-- the SetOpen, OnTouch and Cleanup methods even if we did not
	-- add all of the functions ourself - this is because the
	-- __index metamethod is set in the Door metatable.
	setmetatable(self, Door)
	
	-- Keep track of some door properties of our own
	self.door = door
	self.debounce = false
	
	-- Initialize a Touched event to call a method of the door
	self.touchConn = door.Touched:Connect(function (...)
		self:OnTouch(...)
	end)
	
	-- Initialize the state of the door
	self:SetOpen(false)
	
	-- Print a message so we know when doors are initialized
	print("Initialized door: " .. door:GetFullName())
	
	return self
end
 
function Door:SetOpen(isOpen)
	if isOpen then
		self.door.Transparency = .75
		self.door.CanCollide = false
	else
		self.door.Transparency = 0
		self.door.CanCollide = true
	end
end
 
function Door:OnTouch(part)
	if self.debounce then return end
	local human = part.Parent:FindFirstChild("Humanoid")
	if not human then return end
	self.debounce = true
	self:SetOpen(true)
	wait(Door.OPEN_TIME)
	self:SetOpen(false)
	self.debounce = false
end
 
function Door:Cleanup()
	self.touchConn:disconnect()
	self.touchConn = nil
end
 
------------------------------------------------------------------------------ 
-- In this section of the script, we want to listen for objects with the door
-- tag. When we find one, create a new Door and keep track of it. When the door
-- tag is removed, we'll find the Door we created and destroy it.
 
local doors = {}
 
local doorAddedSignal = CollectionService:GetInstanceAddedSignal(Door.TAG_NAME)
local doorRemovedSignal = CollectionService:GetInstanceRemovedSignal(Door.TAG_NAME)
 
local function onDoorAdded(door)
	if door:IsA("BasePart") then
		-- Create a new Door object and save it
		-- The door class will take over from here!
		doors[door] = Door.new(door)
	end
end
 
local function onDoorRemoved(door)
	if doors[door] then
		-- Clean up an already-existing door
		doors[door]:Cleanup()
		doors[door] = nil
	end
end
 
-- Listen for existing tags, tag additions and tag removals for the door tag 
for _,inst in pairs(CollectionService:GetTagged(Door.TAG_NAME)) do
	onDoorAdded(inst)
end
doorAddedSignal:Connect(onDoorAdded)
doorRemovedSignal:Connect(onDoorRemoved)
#2

Why not calling it when doing :GetTagged()?, make this:
Require the module

In this code:

local collectionService = game:GetService("CollectionService")

local part = script.Parent 
local yeet = game.Workspace.yeet

collectionService:AddTag(part, "Door")
collectionService:AddTag(yeet, "Door")
	
collectionService:GetInstanceAddedSignal("Door"):Connect(function() this doesn't make sense, isn't this function supposed to give me a signal where if i add a tag this event will run?
	print("yes")
end)

for _,v in pairs(collectionService:GetTagged("Door")) do -- This makes sense it prints the parts that have the door tag 
	print(v)
end

All perfect, on this part;

for _,v in pairs(collectionService:GetTagged("Door")) do 
DoorModule.new(v)
print(v.Name)

end
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#3

So if we run DoorModule.new(v), would GetInstanceAddedSignal work?

#4

You’re mixing 2 things.
:GetInstanceAddedSignal() fires when a new object is added to the Collection service table (key)
And no, when you do Door.new() you’re not adding it into the Collection service table

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#5

So if we use addTag(“Tag”) , does getinstanceaddedsignal fire?

#6

If you do :AddTag(object, key) it will fire, if that’s what you mean.

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#7

Thanks I think I understand this a bit better now

1 Like