StringValue赋值报错：Unable to assign property Value. string expected, got nil 求助

我尝试在排行榜统计中创建Rank（类型为StringValue），但出现以下报错：

Unable to assign property Value. string expected, got nil

原始脚本：

-- Rank
local Rank = Instance.new("StringValue", stats)
Rank.Name = "Rank"
Rank.Value = "Newbie"
Rank.Parent = leaderstats

local success = nil
local playerData = nil
local attempt = 1

repeat
    success, playerData = pcall(function()
        return DataBase:GetAsync(player.UserId)
    end)

    attempt += 1
    if not success then
        warn(playerData)
        task.wait(3)
    end
until success or attempt == 5

if success then
    print("Connected to database")
    if not playerData then
        print("Assigning default data")
        playerData = {
            ["Coins"] = 0,
            ["Mcoins"] = 0,
            ["Exp"] = 0,
            ["Level"] = 1,
            ["Rank"] = "Newbie",
            ["ExpNeeded"] = Level.value * 200,
        }
    end
    sessionData[player.UserId] = playerData

else
    warn("Unable to get data for", player.UserId)
    player:Kick("Unable to load your data. Try again later")
end

Rank.Value = sessionData[player.UserId].Rank
Rank.Changed:Connect(function()
    sessionData[player.UserId].Rank = Rank.Value
end)

原因分析 #

• 直接触发报错的原因：当数据加载失败（success为false）时，代码不会执行sessionData[player.UserId] = playerData这一行，此时sessionData[player.UserId]不存在，访问.Rank会返回nil，而StringValue的Value属性要求必须是字符串类型，因此赋值时抛出错误。
• 次要逻辑问题：脚本开头已经给Rank设置了默认值"Newbie"，但后续不管数据加载结果如何都强行覆盖该值，既冗余又会在加载失败时触发报错；另外默认数据中的Level.value是未定义的变量，会引发额外错误。

修复方案 #

1. 仅在数据加载成功后，再用sessionData中的值更新Rank的Value；
2. 修正默认数据中ExpNeeded的计算逻辑，使用刚定义的默认Level值；
3. 确保在数据加载失败的分支中，不会执行后续的Rank赋值代码。

修复后的脚本：

-- Rank
local Rank = Instance.new("StringValue", stats)
Rank.Name = "Rank"
Rank.Value = "Newbie"
Rank.Parent = leaderstats

local success = nil
local playerData = nil
local attempt = 1

repeat
    success, playerData = pcall(function()
        return DataBase:GetAsync(player.UserId)
    end)

    attempt += 1
    if not success then
        warn(playerData)
        task.wait(3)
    end
until success or attempt == 5

if success then
    print("Connected to database")
    if not playerData then
        print("Assigning default data")
        playerData = {
            ["Coins"] = 0,
            ["Mcoins"] = 0,
            ["Exp"] = 0,
            ["Level"] = 1,
            ["Rank"] = "Newbie",
            ["ExpNeeded"] = playerData.Level * 200, -- 修正为使用默认Level值
        }
    end
    sessionData[player.UserId] = playerData
    -- 仅在加载成功时更新Rank值
    Rank.Value = sessionData[player.UserId].Rank
    Rank.Changed:Connect(function()
        sessionData[player.UserId].Rank = Rank.Value
    end)
else
    warn("Unable to get data for", player.UserId)
    player:Kick("Unable to load your data. Try again later")
    -- 加载失败时直接终止，避免后续错误
    return
end

内容的提问来源于stack exchange，提问作者Ruslan Makhmatov