Scripting Helpers is winding down operations and is now read-only. More info→
Ad
Log in to vote
0

Passing custom objects between server side and client side with remote events?

Asked by 6 years ago

Hi all, and Merry Christmas everyone. I'm finally having my first stab at doing some Object Oriented Programming in roblox and have come across a problem when passing objects as arguments into remote events.

The below code shows an example set up.

I have defined a car class with properties position and driver, and created methods TurnLeft and TurnRight. I then instantiate the class in a server script and attempt to pass this object to client side using a remote event.

--module script called Car in game.ReplicatedStorage

--Car Class

Car = {}
Car.__index = Car



function Car.new(position, driver)
    local newcar = {}
    setmetatable(newcar, Car)

    -- Define properties position and driver
    newcar.Position = position
    newcar.Driver = driver

    return newcar
end


function Car:TurnLeft()
    --Turn left code
    print("turning left")
end

function Car:TurnRight()
   --Turn right code
    print("turning right")
end

return Car

.

--server script in workspace

Car = require(game.ReplicatedStorage.Car)

newcar = Car.new(Vector3.new(0,10,0),workspace:WaitForChild("123marble")) -- Instantiation

-- Create remote event
local connectButtonsEvent= Instance.new("RemoteEvent")
connectButtonsEvent.Parent = game.ReplicatedStorage
connectButtonsEvent.Name = "connectButtonsEvent"

-- fire client with argument newcar
connectButtonsEvent:FireClient(game.Players["123marble"],newcar)


.

--local script in StarterPlayerScripts

local connectButtonsEvent = game.ReplicatedStorage:WaitForChild("connectButtonsEvent")

function connectButtons(newcar)
    -- printing properties and then calling method TurnLeft
    print(newcar)
    print(newcar.Driver)
    newcar:TurnLeft()
end

connectButtonsEvent.OnClientEvent:Connect(connectButtons)

The resulting output from the execution of the print statements in the local scipt is this

table: 000001DAD3DE4B00
123marble
12:25:27.535 - Players.123marble.PlayerScripts.LocalScript:6: attempt to call method 'TurnLeft' (a nil value)
12:25:27.536 - Stack Begin
12:25:27.536 - Script 'Players.123marble.PlayerScripts.LocalScript', Line 6
12:25:27.537 - Stack End

It can be seen above that the program is able to print the object, and print a property of the object, but cannot call the method TurnLeft. When calling the method TurnLeft I get error nil as if it does not exist.

Question: Why is it that I am able to access the properties, but not the methods of an object when transferring it between server side and client side using a remote event, and how can I access a custom object on server side and client side with its methods in roblox?

Thank you in advance for any replies!

1
When you pass tables through the network, a copy is sent, not the actual thing, and the metatable is stripped from the copy, so if you applied metamethod it won't work properly. User#24403 69 — 6y
0
Thank you. I just applied the setmetatable metamethod again and now everything works perfectly! 123marble 61 — 6y

1 answer

Log in to vote
-1
Answered by 6 years ago
Edited by User#24403 5 years ago

Although I don't understand all those _index and setmetatable() stuff, I'll do my best! Heh...

function Car:TurnLeft()
    --Turn left code
    print("turning left")
end

function Car:TurnRight()
   --Turn right code
    print("turning right")
end

Something in those lines in the module goes wrong, I assume it doesn't define it correctly? Judging by your output:

table: 000001DAD3DE4B00 123marble 12:25:27.535 - Players.123marble.PlayerScripts.LocalScript:6: attempt to call method 'TurnLeft' (a nil value) 12:25:27.536 - Stack Begin 12:25:27.536 - Script 'Players.123marble.PlayerScripts.LocalScript', Line 6 12:25:27.537 - Stack End


"12:25:27.535 - Players.123marble.PlayerScripts.LocalScript:6: attempt to call method 'TurnLeft' (a nil value)"

Which states that when the localscript calls "TurnLeft", "TurnLeft" doesn't exist (nil) when it calls it from "newcar".


As a noob(me)-fix, because I don't know how else to do it, you could rewrite the module to be like:

--module script called Car in game.ReplicatedStorage

--Car Class

Car = {}
Car.__index = Car

Car = {
new = function(position, driver)
    local newcar = {}
    setmetatable(newcar, Car)

    -- Define properties position and driver
    newcar.Position = position
    newcar.Driver = driver

    return newcar
end,


TurnLeft = function()
    --Turn left code
    print("turning left")
end,

TurnRight = function()
   --Turn right code
    print("turning right")
end,
}

return Car

Hopefully that helps, if it doesn't, sorry I couldn't!

BUT, luckily, judging by my knowledge, it has NOTHING to do with server-client interactions.

If you're wondering why I have two "Cars = {}" it is so the table is defined in the script, so the script itself and the table functions can use Cars and any functions or tables in it.

Ad

Answer this question