How to make a Roblox shop system (with AI)

Files Picoo ships for this prompt

8 files · 1259 lines · one recipe call

Sample output: ServerScriptService/ShopServer.lua

--!strict
-- Generated by Picoo recipe: persistent_shop
local Players = game:GetService("Players")
local DataStoreService = game:GetService("DataStoreService")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local RunService = game:GetService("RunService")

-- (excerpt) opening the DataStore, the catalog, then the purchase handler:

-- GetDataStore itself errors in a place that was never published, and can in
-- Studio without API access. Called bare up here, that one error stopped this
-- whole script before anyone joined. Now a failure only leaves the store nil:
-- every load fails at once, so a Studio play test runs on in memory and saves
-- nothing, and a save (only ever after a load that succeeded) always has it.
local storeOk, storeResult = pcall(function()
	return DataStoreService:GetDataStore("ShopData_v1_inventory")
end)
local INVENTORY_STORE: DataStore? = if storeOk then storeResult else nil
local INVENTORY_STORE_ERROR: string? = if storeOk then nil else tostring(storeResult)
local CURRENCY_FIELD = "Coins"
local PURCHASE_COOLDOWN = 1.0 -- seconds between purchases per player

-- Catalog (authoritative — server source of truth, client can't override prices)
local ITEMS = {
	["sword"] = { name = "Iron Sword", price = 100, description = "Sharp and reliable" },
	["shield"] = { name = "Wooden Shield", price = 50, description = "Basic defense" },
	["potion"] = { name = "Health Potion", price = 25, description = "Restore 50 HP" },
}

PurchaseItem.OnServerInvoke = function(player: Player, itemIdArg: any)
	-- Server validates EVERY arg
	if type(itemIdArg) ~= "string" then return { ok = false, reason = "invalid_args" } end
	local item = ITEMS[itemIdArg]
	if not item then return { ok = false, reason = "unknown_item" } end

	-- Inventory not loaded (load still running, or failed on a live server): the purchase
	-- could not be saved, so don't take coins. A Studio play test shops on, unsaved.
	if not loaded[player.UserId] and not playTest[player.UserId] then return { ok = false, reason = "not_loaded" } end

	-- Per-player purchase cooldown (anti-spam)
	local now = tick()
	if lastPurchase[player.UserId] and (now - lastPurchase[player.UserId]) < PURCHASE_COOLDOWN then
		return { ok = false, reason = "cooldown" }
	end
	lastPurchase[player.UserId] = now

	-- Currency check (server price authoritative, not client-provided)
	local currency = ensureLeaderstats(player)
	if not currency then return { ok = false, reason = "no_leaderstats" } end
	if currency.Value < item.price then
		return { ok = false, reason = "insufficient_funds", needed = item.price, have = currency.Value }
	end

	-- Apply purchase
	currency.Value = currency.Value - item.price
	local inv = inventoryCache[player.UserId] or {}
	inventoryCache[player.UserId] = inv
	inv[itemIdArg] = (inv[itemIdArg] or 0) + 1
	saveInventory(player)
	-- (excerpt) PicooFeedback purchase popup, chime and particles, then:
	return { ok = true, item_id = itemIdArg, new_count = inv[itemIdArg], remaining_currency = currency.Value }
end