MongoDB查询排序出现异常，请各位大大指点一下

[BonneauYang]

由于服务器排行榜处理大数的需要，我将排行榜字段存储为字符串。数据库版本为MongoDB 3.6. 在服务器启动时，需要初始化排行榜数据，这里只排前100。我的想法是先将排行榜字段按小数点分割为整数部分和小数部分，然后对比整数部分字符串的长度，长度越大则排行靠前，长度一致时对比字符串，按字典顺序即可。整数部分一致的话，则对比小数部分字符串，直接对比字符串即可。此逻辑我也在MongoDB Compass里验证了，确实可行。
测试数据如下：
[{"level":"50","role_name":"游客6957681","rid":6957681}}, {"level":"3948","role_name":"游客7624305","rid":7624305}, {"level":"98.5","role_name":"游客3430001","rid":3430001}, {"level":"100.0", "role_name":"test","rid":3287665}, {"level":"100","role_name":"游客7481969","rid":7481969}, {"level":"98","role_name":"游客2905713","rid":2905713}]
MongoDB Compass相关操作如下：
[ { $addFields: { integerPart: { $cond: { if: { $gte: [ { $indexOfCP: [ "$level", ".", ], }, 0, ], }, then: { $substrCP: [ "$level", 0, { $indexOfCP: [ "$level", ".", ], }, ], }, else: "$level", }, }, decimalPart: { $cond: { if: { $gte: [ { $indexOfCP: [ "$level", ".", ], }, 0, ], }, then: { $substrCP: [ "$level", { $add: [ { $indexOfCP: [ "$level", ".", ], }, 1, ], }, { $subtract: [ { $strLenCP: "$level", }, { $add: [ { $indexOfCP: [ "$level", ".", ], }, 1, ], }, ], }, ], }, else: "", }, }, integerPartLength: { $cond: { if: { $gte: [ { $indexOfCP: [ "$level", ".", ], }, 0, ], }, then: { $strLenCP: { $substrCP: [ "$level", 0, { $indexOfCP: [ "$level", ".", ], }, ], }, }, else: { $strLenCP: "$level", }, }, }, }, }, { $sort: { integerPartLength: -1, integerPart: -1, decimalPart: -1, }, }, ]
验证结果如下：
[{"level":"3948","role_name":"游客7624305","rid":7624305,"integerPart":"3948","decimalPart":"","integerPartLength":4}, {"level":"100.0", "role_name":"test","integerPart":"100","rid":3287665,"decimalPart":"0","integerPartLength":3}, {"level":"100","role_name":"游客7481969","rid":7481969,"integerPart":"100","decimalPart":"","integerPartLength":3},{"level":"98.5","role_name":"游客3430001","rid":3430001,"integerPart":"98","decimalPart":"5","integerPartLength":2}, {"level":"98","role_name":"游客2905713","rid":2905713,"integerPart":"98","decimalPart":"","integerPartLength":2}, {"level":"50","role_name":"游客6957681","rid":6957681,"integerPart":"50","decimalPart":"","integerPartLength":2}]
lua代码如下：
`
---初始化排行榜
---@param rankProperty string @排序属性
---@param rankSkipQuantity number @排行榜跳过数量
---@param rankLimitQuantity number @排行榜限制数量
---@return PlayerPublicInfo[], number, number @排行榜信息数据列表, 全部排行数量, 查询排行数量
function CenterServerMongodbManager:initRank(rankProperty, rankSkipQuantity, rankLimitQuantity)
---@type table @mongodb配置
local mongodbsConfig = configdao.get_svrs_config("mongo_dbs")

---@type MongoAggregateStruct @聚合语句结构
local aggregateStruct = {}
aggregateStruct.collection = PlayerInfoCollection
aggregateStruct.pipeline = {
    {
        ["$addFields"] = {
            integerPart = {
                ["$cond"] = {
                    ["if"] = { ["$gte"] = { { ["$indexOfCP"] = { "$" .. rankProperty, "." } }, 0 } },
                    ["then"] = { ["$substrCP"] = { "$" .. rankProperty, 0, { ["$indexOfCP"] = { "$" .. rankProperty, "." } } } },
                    ["else"] = "$" .. rankProperty
                },
            },
            decimalPart = {
                ["$cond"] = {
                    ["if"] = { ["$gte"] = { { ["$indexOfCP"] = { "$" .. rankProperty, "." } }, 0 } },
                    ["then"] = {
                        ["$substrCP"] = {
                            "$" .. rankProperty,
                            { ["$add"] = {
                                { ["$indexOfCP"] = { "$" .. rankProperty, "." } },
                                1
                            } },
                            { ["$subtract"] = {
                                { ["$strLenCP"] = "$" .. rankProperty },
                                { ["$add"] = {
                                    { ["$indexOfCP"] = { "$" .. rankProperty, "." } },
                                    1
                                } }
                            } }
                        }
                    },
                    ["else"] = ""
                },
            },
            integerPartLength = {
                ["$cond"] = {
                    ["if"] = { ["$gte"] = { { ["$indexOfCP"] = { "$" .. rankProperty, "." } }, 0 } },
                    ["then"] = { ["$strLenCP"] = { ["$substrCP"] = { "$" .. rankProperty, 0, { ["$indexOfCP"] = { "$" .. rankProperty, "." } } } } },
                    ["else"] =  { ["$strLenCP"] = { ["$ifNull"] = {"$" .. rankProperty, ""} } }
                },
            },
    },
    {
        ["$project"] = {
            _id = 0, rid = 1, role_name = 1, logo = 1, frame = 1, custom_property = 1,
            integerPart = 1, decimalPart = 1, integerPartLength = 1
        }
    },
    {
        ["$sort"] = {
            integerPartLength = -1,
            integerPart = -1,
            decimalPart = -1
        }
    }
}

if rankSkipQuantity > 0 then
    table.insert(aggregateStruct.pipeline, { ["$skip"] = rankSkipQuantity })  -- MongoDB聚合语句中不能包含空字段，即{}
end
if rankLimitQuantity > 0 then
    table.insert(aggregateStruct.pipeline, { ["$limit"] = rankLimitQuantity })  -- MongoDB聚合语句中不能包含空字段，即{}
end
table.insert(aggregateStruct.pipeline, { ["$project"] = { _id = 0, rid = 1, role_name = 1, logo = 1, frame = 1, custom_property = 1 } })

---查询MongoDB数据
local success, rankInformations, totalRankCount, findRankCount = skynet.call(mongodbsConfig.gamedatadb.server_id, "lua", "aggregate", aggregateStruct)
if not success or not baseTool.is_table(rankInformations) then
    filelog.sys_error(__filename, "初始化 " .. mainSortProperty .. " 排行榜失败", rankInformations, mainSortProperty, secondarySortProperty, rankSkipQuantity, rankLimitQuantity)
    rankInformations = nil
end

return rankInformations.cursor.firstBatch, totalRankCount, findRankCount

end
最终出现错误查询数据如下：{{"level":"98.5","role_name":"游客3430001","rid":3430001,"integerPart":"98","decimalPart":"5","integerPartLength":2}, {"level":"100.0", "role_name":"test","integerPart":"100","rid":3287665,"decimalPart":"0","integerPartLength":3}, {"level":"3948","role_name":"游客7624305","rid":7624305,"integerPart":"3948","decimalPart":"","integerPartLength":4}, {"level":"100","role_name":"游客7481969","rid":7481969,"integerPart":"100","decimalPart":"","integerPartLength":3}, {"level":"98","role_name":"游客2905713","rid":2905713,"integerPart":"98","decimalPart":"","integerPartLength":2}, {"level":"50","role_name":"游客6957681","rid":6957681,"integerPart":"50","decimalPart":"","integerPartLength":2}}`
请问各位大大，为什么会出现这种情况吖？是lua的原因么