Roblox save data with datastore script

-- Save data: loads Coins when a player joins and saves when they leave.
-- This script makes the leaderstats itself. Do not also use the Leaderstats (coins) script.

local STORE_NAME = "PlayerData_v1"   -- change the name to start with a fresh, empty store
local DEFAULT_COINS = 0
local AUTOSAVE_SECONDS = 120
local MAX_TRIES = 3

local Players = game:GetService("Players")
local DataStoreService = game:GetService("DataStoreService")

local store = DataStoreService:GetDataStore(STORE_NAME)
local loaded = {}   -- players whose data loaded OK. We only save these.

-- Runs fn up to MAX_TRIES times. Returns true and the result, or false.
local function tryCall(fn)
	for attempt = 1, MAX_TRIES do
		local ok, result = pcall(fn)
		if ok then
			return true, result
		end
		warn("DataStore call failed (try " .. attempt .. "): " .. tostring(result))
		task.wait(2)
	end
	return false, nil
end

local function keyFor(player)
	return "Player_" .. player.UserId
end

local function savePlayer(player)
	if not loaded[player] then
		return -- the load failed, so saving would wipe real data with defaults
	end

	local leaderstats = player:FindFirstChild("leaderstats")
	local coins = leaderstats and leaderstats:FindFirstChild("Coins")
	if not coins then
		return
	end

	local data = { Coins = coins.Value }
	local ok = tryCall(function()
		store:SetAsync(keyFor(player), data)
	end)
	if not ok then
		warn("Could not save data for " .. player.Name)
	end
end

local function onPlayerAdded(player)
	local leaderstats = Instance.new("Folder")
	leaderstats.Name = "leaderstats"
	leaderstats.Parent = player

	local coins = Instance.new("IntValue")
	coins.Name = "Coins"
	coins.Value = DEFAULT_COINS
	coins.Parent = leaderstats

	local ok, data = tryCall(function()
		return store:GetAsync(keyFor(player))
	end)

	if not ok then
		warn("Could not load data for " .. player.Name .. ". Their progress will not be saved this visit.")
		return
	end

	if type(data) == "table" and type(data.Coins) == "number" then
		coins.Value = data.Coins
	end
	loaded[player] = true
end

local function onPlayerRemoving(player)
	savePlayer(player)
	loaded[player] = nil
end

Players.PlayerAdded:Connect(onPlayerAdded)
Players.PlayerRemoving:Connect(onPlayerRemoving)

for _, player in Players:GetPlayers() do
	task.spawn(onPlayerAdded, player)
end

-- Save everyone when the server shuts down.
game:BindToClose(function()
	for _, player in Players:GetPlayers() do
		task.spawn(savePlayer, player)
	end
	task.wait(3)
end)

-- Save everyone every couple of minutes in case of a crash.
task.spawn(function()
	while true do
		task.wait(AUTOSAVE_SECONDS)
		for _, player in Players:GetPlayers() do
			task.spawn(savePlayer, player)
		end
	end
end)