mongodb - 如何在 Mongoose 中为数组中的每个值添加一个字符串？

Question

假设我有一组这样的文件......

{ name: "Bob", listIDs: ["1c2f", "32a1", "0ebf"] }
{ name: "Meg", listIDs: ["a844", "8132", "b246"] }
...

我如何为每个文档的 listIDs 中的每个值添加字符串“0000”？例如

{ name: "Bob", listIDs: ["00001c2f", "000032a1", "00000ebf"] }
{ name: "Meg", listIDs: ["0000a844", "00008132", "0000b246"] }
...

Answer 1

你可以试试update with aggregation pipeline从 MongoDB 4.2 开始，

$map迭代 listIDs 的循环阵列

$concat连接 0000具有元素值

db.collection.updateMany({},
  [{
    $set: {
      listIDs: {
        $map: {
          input: "$listIDs",
          in: { $concat: ["0000", "$$this"] }
        }
      }
    }
  }]
)

Playground