Load and validate player data

Syntax

-- ready only after successful read AND validation
-- failed read → no gameplay writes and no save

Examples

local store = game:GetService("DataStoreService"):GetDataStore("LessonProgress_TEST_v1")
local LessonLoad = {}
function LessonLoad.load(userId)
    local ok, raw = pcall(function()
        return store:GetAsync("player:" .. tostring(userId))
    end)
    if not ok then return nil, "Read failed" end
    if raw == nil then return {version = 1, highestLesson = 0} end
    if type(raw) ~= "table" or raw.version ~= 1 then return nil, "Unsupported record" end
    local highest = raw.highestLesson
    if type(highest) ~= "number" or highest ~= highest or highest < 0 or highest > 32 or highest % 1 ~= 0 then
        return nil, "Invalid progress"
    end
    return {version = 1, highestLesson = highest}
end
return LessonLoad

local Players = game:GetService("Players")
local LessonLoad = require(script.Parent:WaitForChild("LessonLoad"))
local started, sessions = {}, {}
local function onPlayer(player)
    if started[player] then return end
    started[player] = true
    local data = LessonLoad.load(player.UserId)
    if player.Parent ~= Players then return end
    if not data then
        player:Kick("Progress could not be loaded. Please rejoin later.")
        return
    end
    sessions[player] = {ready = true, data = data}
    print("Loaded", player.Name, data.highestLesson)
end
Players.PlayerAdded:Connect(onPlayer)
Players.PlayerRemoving:Connect(function(player)
    sessions[player], started[player] = nil, nil
end)
for _, player in Players:GetPlayers() do task.spawn(onPlayer, player) end

Best practices

• Never write defaults after pcall returns false, or after validation rejects a record.
• Do not silently reinterpret an unknown schema version as a new player.
• Keep loading, ready, saving and failed states explicit; only trusted server actions may change a ready session.

At a glance

Purpose

Typed scripting and Roblox development

File extension

.luau

Runs in

Luau host; Roblox engine examples require Roblox Studio

Usually used with

Roblox APIs and Studio

Specifications & further reading

• Roblox Creator Hub
• Roblox Creator Hub

Related Luau documentation