尝试索引nil值(字段'?')关于FiveM essentialmode

Question

我有一个问题在代码的一部分，我不是程序员，我在互联网上看了看，但我没有找到任何有用的东西，问题是在第234行，这是if groups[Users[source].getGroup()]:canTarget(group) then idk做什么，这是错误

Error running call reference function for resource essentialmode: citizen:/scripting/lua/scheduler.lua:351: server/main.lua:234: attempt to index a nil value (field '?') stack traceback: server/main.lua:234: in upvalue 'ref' citizen:/scripting/lua/scheduler.lua:337: in function citizen:/scripting/lua/scheduler.lua:336 [C]: in function 'xpcall' citizen:/scripting/lua/scheduler.lua:336: in function citizen:/scripcfx ting/lua/scheduler.lua:335> stack traceback: [C]: in function 'error' citizen:/scripting/lua/scheduler.lua:351: in function citizen:/scripting/lua/scheduler.lua:322

function addGroupCommand(command, group, callback, callbackfailed, suggestion)
commands[command] = {}
commands[command].perm = math.maxinteger
commands[command].group = group
commands[command].cmd = callback
commands[command].callbackfailed = callbackfailed

if suggestion then
    if not suggestion.params or not type(suggestion.params) == "table" then suggestion.params = {} end
    if not suggestion.help or not type(suggestion.help) == "string" then suggestion.help = "" end

    commandSuggestions[command] = suggestion
end

ExecuteCommand('add_ace group.' .. group .. ' command.' .. command .. ' allow')

RegisterCommand(command, function(source, args)
    if groups[Users[source].getGroup()]:canTarget(group) then
        callback(source, args, Users[source])
    else
        callbackfailed(source, args, Users[source])
    end
end)

debugMsg("Group command added: " .. command .. ", requires group: " .. group)          end

Answer 1

Lua只接受从1开始的索引，当索引为0时，我通常会得到这个错误。因此，您可以检查source或Users[source].getGroup()是否可能等于0，确保它们始终为>= 1。

Answer 2

有点晚了，但供其他在这里登陆的人参考：

当在日志中得到错误时，比如

citizen:/scripting/lua/scheduler.lua:351: server/main.lua:234: attempt to index a nil value (field '?')

这往往是因为从数据库获取的数据是空的。

例如,

Error running call reference function for resource esx_identity: citizen:/scripting/lua/scheduler.lua:405: @esx_identity/server/main.lua:11: attempt to index a nil value (field '?')
stack traceback:
@esx_identity/server/main.lua:11: in upvalue 'ref'

esx_identity/server/main.lua中的第11行是：

if result[1].firstname ~= nil then

引用的firstname是从数据库返回的空值。SQL查询通常非常接近有问题的代码行。

检查数据库中是否有包含空值的行，并删除或修复任何存在的行。