Hello! This is a post about CollectionService, in a nutshell.
What’s CollectionService? Well, CollectionService is a service which allows you to manage groups of instances using tags which are simple strings, but you can’t see them.
CollectionService is very useful, since it allows us to run functions or change properties from large groups of parts with a single script, instead of having 10 scripts that do the same, you only have 1. Learning how to use this Service will save us tons of lanes of code.
Let’s start by learning the basics about CollectionService, let’s create our first tag and let’s tag our first part.
1. Learning the Basics
Before starting with the functions, let’s set up our variables
local CollectionService = game:GetService("CollectionService")
--The service we're going to use
local instance0 = Instance.new("Part")
instance0.Name = "instance0"
local instance1 = Instance.new("Folder")
instance1.Name = "instance1"
-- The instances we're going to work with, a part and a folder,
-- remember that any instance can be tagged.
:AddTag(instance, string)
Our first function is :AddTag() and it will basically tag an instance with the given tag. If the tag does not exist, :AddTag() will create a new tag and then will tag the given instance.
CollectionService:AddTag(instance0, "Tag_A")
But… we can’t know if the part is actually tagged, because the tag is invisible for us even in studio, so let’s see the next one.
:GetTags(instance)
:GetTags() will return a table with all the tags of the given instance, keep in mind that it returns tables and not strings.
local instance0_tags = CollectionService:GetTags(instance0)
local instance1_tags = CollectionService:GetTags(instance1)
print(instance0_tags) --> {"Tag_A"}
print(instance1_tags) --> {}
-- Keep in mind that :GetTags() returns an array of strings, not a string.
print(instance0_tags[1]) --> "Tag_A"
:GetTagged(string)
:GetTagged() is pretty similar to :GetTags(), but instead of returning the tags of an instance, it will return all the instances with a given tag.
local tagged_instances_A = CollectionService:GetTagged("Tag_A")
local tagged_instances_B = CollectionService:GetTagged("Tag_B")
print(tagged_instances_A) --> {instance0}
print(tagged_instances_B) --> {}
-- Keep in mind that :GetTagged() returns an array of instances, not an instance,
-- neither a string.
print(tagged_instances_A[1]) --> instance0
print(tagged_instances_A[1].Name) --> "instance0"
:RemoveTag(instance, string)
:RemoveTag() removes a desired tag from an instance, and yup… that’s all it does.
CollectionService:AddTag(instance0, "Tag_A")
CollectionService:AddTag(instance0, "Tag_B")
print(CollectionService:GetTags(instance0)) --> {"Tag_A", "Tag_B"}
CollectionService:RemoveTag(instance0, "Tag_A")
print(CollectionService:GetTags(instance0)) --> {"Tag_B"}
:HasTag(instance, string)
This one is important, so watch out. :HasTag() checks if an instance has got a specified tag, the value in return will be true or false, depending on wherever the instance has got that tag or not.
CollectionService:AddTag(instance0, "Tag_B")
if (CollectionService:HasTag(instance0, "Tag_A")) then
print("yeah cool, you won some beans")
else
print("uhhh you've been a bad boy")
end
--> Output: "uhhh you've been a bad boy"
:GetInstanceAddedSignal() & :GetInstanceRemovedSignal()
These 2 functions will fire a callback function when an instance is added/removed from a specified tag.
CollectionService:GetInstanceAddedSignal("Tag_A"):Connect(function(instance)
print(instance.Name.." marked as Tag_A")
end)
CollectionService:GetInstanceRemovedSignal("Tag_A"):Connect(function(instance)
print(instance.Name.." unmarked as Tag_A")
end)
CollectionService:AddTag(instance0, "Tag_A") --> "instance0 marked as Tag_A"
CollectionService:RemoveTag(instance0, "Tag_A") --> "instance0 unmarked as Tag_A"
2. Using CollectionService
Now that we know all the functions, let’s see what we can do with this.
As said before, with CollectionService we can run codes or change properties of big groups of parts, how? Let’s take a look on how to do it.
So, Imagine that you have 3 parts and you want them to kill the player if it touches them, what would you do?
No! Never do that again, that’s time consuming and can even lead to problems.
Okay that’s better. In this situation, there are only 3 parts, so It would be very easy to get the 3 parts and connect them to a function, but imagine that instead of 3 parts, you have 500, uh, It wouldn’t be that easy to connect the 500 parts one by one. In this case, we can use CollectionService, which is way better than connecting each part one by one.
local CollectionService = game:GetService("CollectionService")
--// First, we will loop trough all the parts with the "killers" tag using a for loop.
for _, part in pairs(CollectionService:GetTagged("killers")) do
--[[
Now that we've got our killer parts, we're gonna bind them to a function,
so when they get touched, they will fire that function.
--]]
part.Touched:Connect(function(hit)
--// Classic killing brick script, nothing very interesting
if (hit.Parent:FindFirstChild("Humanoid")) then
local humanoid = hit.Parent.Humanoid
humanoid.Health = humanoid.Health - humanoid.MaxHealth
end
end)
end
And now we have our 3 functional killer parts, and everything in less than 25 lines of code and just using one script. The best thing of all is that we can easily change the script whenever we want and our parts will still work. Just imagine if you had to manage 300 killing bricks without CollectionService.
Well, maybe you’re thinking about using for loops to iterate through all the parts and connect them to a function, actually, that is what we did in the code above us, but there’s one little difference between using for loops and using CollectionService. If you wanted to use for loops to do this, you would have to give the parts a Key name or insert some sort of value into them so the script could know they are the correct parts, by using CollectionService, you can avoid those steps.
If you’re going to use CollectionService for your game, I really, really (just do it) recommend you installing Tag Editor Plugin, you can find a detailed explanation about it in the next paragraph.
3. Editing tags easily
Tag Editor Plugin
As I said before, @Sweetheartichoke’s plugin, Tag Editor Plugin, is basically a plugin that makes It easier & faster to manipulate tags on Roblox Studio.
If you want detailed information about the Plugin and you want to get it, check the original post linked above, but here I’m gonna show you the basics and how to use this plugin to make your life much more easier when using tags.
Let’s imagine I want to create a new tag for the killing parts, instead of creating a whole script using :AddTag() & looping through a folder or group of parts, I will open Tag Editor and I will type the name of my new tag
Press enter and… there it goes, your new tag without having to script nothing
Now that we have our tag, we just have to select the parts and apply that tag to the parts.
If you want to know if you really tagged your parts, you can check it out activating World View. (also from the Tag Editor Plugin).
And now you will be able to see an outline, or a box at all the parts tagged with the tag that you selected.
And now that you have your tags created, you can freely use them in your scripts, amazing!
Well, that’s all about CollectionService, hope It was useful. If you want to know more about the Tag Editor Plugin just go and check the official post and get it!
