How do I wait until a function returns data?

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#1

Basically I have code that is suppose to get data from a function, but the data doesnt get returned in an instant, so how do I make it wait til the data gets returned?

Trigger Code

AnimateButton.Click:Connect(function()
	displayMsg(true,'SELECT RIGS TO ANIMATE')
	
	local s = getSelected()
	
	print(s)
	
	if s then
		print(s)
	end
end)

Function

local function getSelected()

	
	uis.InputBegan:Connect(function(input)
		if input.KeyCode == Enum.KeyCode.R then
			print('Gettin selections')
			local s = {}
			for _, item in pairs(selectionService:Get()) do
				if item:FindFirstChildOfClass('Humanoid') then
					s[item.Name] = item
				end
			end
			return s
		end
	end)
end
#2 
AnimateButton.Click:Connect(function()
	displayMsg(true,'SELECT RIGS TO ANIMATE')
	local s = nil
	s = getSelected()
    
	repeat 
		task.wait()
    until (s ~= nil)
	
	print(s)
end)
1 Like
#3

This didnt work, I made it print “Yes” after it S should be equal to something but it never is or something

	displayMsg(true,'SELECT RIGS TO ANIMATE')
	
	local s = getSelected()
	
	local t = 30
	
	repeat 
		task.wait() t -= 0.03 
	until (s ~= nil) or t <= 0
	
	print('yes') -- never gets printed
	displayMsg(false)
	
	if s then
		print(s)
	else
		warn('DID NOT SELECT ANY RIGS')
	end
#4

That is because you’re not inserting any data into s. You should use table.insert instead.

#5

Therefore:

local function getSelected()
    uis.InputBegan:Connect(function(input)
        
		if input.KeyCode == Enum.KeyCode.R then
		    local Return = {}
			print('Gettin selections')
			
			for _, item in pairs(selectionService:Get()) do

				if item:FindFirstChildOfClass('Humanoid') then
					table.insert(Return, item)

				end
			end
			
			return Return
			
		end
	end)
end
1 Like
#6

Yes they are?

This is inserting an item into the s table

#7

It should insert the value then. I don’t know whether table[i.Name] = i is correct, however.

#8

It does, can confirm.

@FroDev1002 could you print s BEFORE the repeat until loop and see what it prints?

#9

this is true, I remember that table.insert would work instead of the other method

#10

Tried doing this, it still returns nil even though there are things in S. I print it before I return it.

#11

Just btw, I’m fairly certain this will cause a memory leak because the UIS.InputBegan connection is not disconnected and is reconnected every click of the UI button.

#12

Dont worry I will disconnect it later, I was trying to figure this out first

#13

RBXScriptSignal has a /Wait method that yields the thread and then resumes with the arguments once the event is fired. So instead of /Connect, you could do:

local function getSelected()
	local input, wasProcessed = UserInputService.InputBegan:Wait()
	
	if not wasProcessed and input.KeyCode == Enum.KeyCode.R then
		...
	end
end

You could also put it in a loop to retry yielding in the case the user input something that wasn’t R or was processed.

#14

Ok but what about actually returning the value? Unless this is to do with that. Im dum obv

#15

You could possibly do this:

local runService = game:GetService("RunService")
local function getSelected()
    local items = nil
	local connection = uis.InputBegan:Connect(function(input) -- store the connection so it can be disconnected later
		if input.KeyCode == Enum.KeyCode.R then
			print('Gettin selections')
			local s = {}
			for _, item in pairs(selectionService:Get()) do
				if item:FindFirstChildOfClass('Humanoid') then
					s[item.Name] = item
				end
			end
			items = s -- set the items variable to 's'
		end
	end)

    while not items do -- yield the thread until the 'items' variable isn't nil
       runService.Heartbeat:Wait() -- wait every frame
    end
    connection:Disconnect() -- disconnect the input connection
    return items -- return the data
end
1 Like
#16

this could possibly work, i haven’t tested it though:

local function getSelected()
	local running = coroutine.running()
	uis.InputBegan:Connect(function(input)
		if input.KeyCode == Enum.KeyCode.R then
			print('Gettin selections')
			local s = {}
			for _, item in pairs(selectionService:Get()) do
				if item:FindFirstChildOfClass('Humanoid') then
					s[item.Name] = item
				end
			end
			coroutine.resume(running)
			return s
		end
	end)
	coroutine.yield()
end

no weird while loops, though I’m concerned about how you are not disconnecting the inputbegan event

#17

You should look into using an open source module such as promise which provides a ton of methods for pausing the thread until data has been returned.
https://eryn.io/roblox-lua-promise/

1 Like
#18

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