Wierd Instance:IsDescendantOf() Behavior on The Client

[AreaRankDragon (Era)]

Hi folks! Today I have something to show and would like to ask why exactly it happens. I’ll demonstrate.

So we have this small script

for _,v in pairs(game.Workspace:GetDescendants()) do
	if v:IsA('BasePart') then
		local isplr = false
		for _,p in pairs(game.Players:GetPlayers()) do
			if v:IsDescendantOf(p.Character) then
				isplr = true
			end
		end
		if not isplr then
			print('"' ..v.Name ..'" is not in a player character')
		end
	end
end

the code is self explanatory, go through all BaseParts in workspace and tell me if they’re not a descendant of a player’s character. now we put this in ServerScriptService and see if it works…

aaand it works as expected, but here’s the part that bothers me, if we now turn this into a localscript and put it in StarterPlayerScripts and uhhh

and nothing, if you change the code in this manor:

for _,v in pairs(game.Workspace:GetDescendants()) do
	if v:IsA('BasePart') then
		local isplr = false
		for _,p in pairs(game.Players:GetPlayers()) do
			if v:IsDescendantOf(p.Character) then
				isplr = true
			end
		end
		if isplr then
			print('"' ..v.Name ..'" is in a player character')
		end
	end
end

then uhhhhhhh

now it says that EVERYTHING is a descendant of a player character. The solution to fix this is to either put the code in StarterCharacterScripts or to add the following before the block of code

game.Players.LocalPlayer.CharacterAdded:Wait()

This works fine for what i want to do in my case, but I’d like to know why this exactly happens or if this is intentional or not.

That’s all, have a nice day

[majdTRM]

Not sure if I’m mistaken but it might be buggy because it’s a new feature. FindFiratDescendant for example is disabled via FFlag because it is in beta.

[Noob_McDev (Noob)]

While weird there is an explanation. Before your player’s character spawns the Player.Character attribute will be nil. Since the DataModel (game) has a parent of nil, if you pass nil as an argument to Instance.IsDescendantOf() you get true. The logic being that your parts are descendant of game which is a descendant of nil. So another way to “fix” your code would be to make sure p.Character is not nil.

From Instance.IsDescendantOf()

Note, DataModel is a descendant of nil. This means IsDescendantOf cannot be used with a parameter of nil to check if an object has been removed.

[AreaRankDragon (Era)]

Oh ok now that makes sense, thanks for the explanation!