Question

结构：

String str = "11020199,Abc Germany ,aduz,,444,bieb,dc,2 ,2222.00,whatever 5dc,222.22,22.00,\"\"98,00\"\",\"\"12,00\"\",21-09-2018,06:00";

// Replace the comma between double quotes with a replacement char you're sure isn't in the String:
// TODO: Use a more suitable character, I don't know what your text can/cannot contain
String modifiedStr = str.replaceAll("(\"\"[^,]+),([^,]+\"\")", "$1$2");

// Now split by comma:
String[] array = modifiedStr.split(",");

// And then change the replacement char back again to a comma:
for(int i=0; i<array.length; i++)
  array[i] = array[i].replace("", ",");

我想在我的文件字段的每个数组元素中添加计算字段（Number），并将其值设置为同一元素（即类型）中的其他字段。我已经尝试过使用聚合框架，但是每次我设置值时，它都会从整个数组中获取所有值，即：

"entity": [
    {
        "_id": {
            "$oid": "5bbf6e6d69a634eeb5a32a0e"
        },
        "Extension Id": "PR00027173",
        "Files": [
            {
                "Locale": "en_WW",
                "FileExtension": "ai",
                "Number": []
            },
            {
                "Locale": "sv_SE",
                "Type": "Technical drawing",
                "FileExtension": "eps",
                "Number": []
            }
        ]
    },
    {
        "_id": {
            "$oid": "5bbf6e6d69a634eeb5a32b7c"
        },
        "Extension Id": "PR00027174",
        "Files": [
            {
                "Locale": "en_WW",
                "FileExtension": "ai",
                "Number": []
            },
            {
                "Locale": "sv_SE",
                "Type": "Technical drawing",
                "FileExtension": "eps",
                "Number": []
            }
        ]
    }
]

是否可以将新字段Number值设置为FileExtension，但只能从同一元素而不是整个数组？这就是我的投影总的样子：

"Files": [
            {
                "Locale": "en_WW",
                "FileExtension": "ai",
                "Number": [
                    "ai",
                    "eps"
                ]
            },
            {
                "Locale": "sv_SE",
                "Type": "Technical drawing",
                "FileExtension": "eps",
                "Number": [                        
                    "ai",
                    "eps"
                ]
            }
]

Answer 1

这对于标准投影是不可能的，因为它是一个数组。您必须使用数组运算符$map来设置数组元素。

类似

db.collection.aggregate([
  ...other stages..
  {"$addFields":{
      "Files":{
        "$map":{
         "input":"$Files",
         "in":{
             "Locale": "$$this.Locale",
             "FileExtension": "$$this.FileExtension",
             "Number":"$$this.FileExtension"
          }
        }
      }
   }}
])

使用另一个字段作为值将计算字段添加到每个数组元素

1 个答案: