从 mongodb 阵列中的所有重复项中拉出一个元素

Question

This is my array in MongoDB:

cardOwners: Array
0: "9999"
1: "4444"
2: "4444"
3: "4444"

I want to ONLY pull and remove 1 of the "4444" elements in the array, but it pulls away all of them when I try it out.

Is there anything I can do to just remove 1 of the duplicate ones?

Answer 1

you can use this approach

let result = await card.findOne({filter })
const index = result.cardOwners.findIndex(element => element === "4444");
result.cardOwners.splice(index, 1);
await result.save()