Mongodb：项目只从字符串中获取数值

Question

是否有任何逻辑作为javascript替换（/ [^ \ d。] / g，''）方法。只获取字符串的数值。

从字符串中只获取整数

样本文件：

{
    "_id" : "1",
    "planName" : "Options Silver 1431B"
}
{
    "_id" : "1",
    "planName" : "Options Silver 1431A"
}
{
    "_id" : "1",
    "planName" : "myOptions 1431A"
}
{
    "_id" : "1",
    "planName" : "myOptions 1431"
}
{
    "_id" : "1",
    "planName" : "myOptions 1431A",

}

结果：

   {
        "_id" : "1",
        plan_id: "1431"
   },
   {
        "_id" : "1",
        plan_id: "1431"
   },
   {
        "_id" : "1",
        plan_id: "1431"
   },
   {
        "_id" : "1",
        plan_id: "1431"
   },
   {
       "_id" : "1",
        plan_id: "1431"
   }

Answer 1

您可以使用聚合框架分三步完成：

1. 使用$map和$range将您的字符串转换为字符数组与$substrCP
2. 使用$filter只保留数值（"0" - "9"）
3. 使用$reduce将它们连接成一个字符串

   db.col.aggregate([
       {
           $addFields: {
               chars: {
                   "$map":{
                       "input":{
                           "$range":[
                               0,
                               {
                                   "$strLenCP":"$planName"
                               }
                           ]
                       },
                       "in":{
                           "$substrCP":[
                               "$planName",
                               "$$this",
                               1
                           ]
                       }
                   }
               }
           }
       },
       {
           $project: {
               numbers: {
                   $filter: {
                    input: "$chars",
                    as: "char",
                    cond: { $and: [
                       { $gte: [ "$$char", "0" ] },
                       { $lte: [ "$$char", "9" ] }
                     ] }
                 }
               }
           }
       },
       {
           $project: {
               plan_id: { 
                   $reduce: {
                     input: "$numbers",
                     initialValue: "",
                     in: { $concat : ["$$value", "$$this"] }
                   }
               }
           }
       }
   ])