如何使用golang删除MongoDB数组中的第N个元素？

Question

我需要删除第一个或第二个元素expenses{"_id":{"$oid":"12"},"chatID":{"$numberInt":"12"},"expenses":[   {"category":"food","amount":{"$numberDouble":"12.0"}},   {"category":"food","amount":{"$numberDouble":"14.0"}}],"income":[]}喜欢expenses[0].Delete()结果应该是这样的：{"_id":{"$oid":"12"},"chatID":{"$numberInt":"12"},"expenses":[   {"category":"food","amount":{"$numberDouble":"14.0"}}],"income":[]}

Answer 1

您必须使用$unset更新命令并手动提及数组键名及其索引。

更新命令：

_, err = collection.UpdateOne(

        ctx,

        bson.D{},  // <- Find Parameter

        bson.D{

            {"$unset", bson.D{

                {"expenses."+indexToRemove, 1},  // <- Removes `indexToRemove` th element from `expenses` array

            }},

        },

    )

完整的代码

package main

import (

    "context"

    "fmt"

    "go.mongodb.org/mongo-driver/bson"

    "go.mongodb.org/mongo-driver/mongo"

    "go.mongodb.org/mongo-driver/mongo/options"

    "time"

)

func main() {

    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

    defer cancel()

    mClient, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://localhost:27017"))

    defer func() {

        if err = mClient.Disconnect(ctx); err != nil {

            panic(err)

        }

    }()

    collection := mClient.Database("temp").Collection("tmp10")

    ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)

    defer cancel()

    var result bson.M

    err = collection.FindOne(ctx, bson.D{}).Decode(&result)

    fmt.Println(result)

    indexToRemove := "0"  // <- Input index to remove in string or convert it into string

    _, err = collection.UpdateOne(

        ctx,

        bson.D{},

        bson.D{

            {"$unset", bson.D{

                {"expenses."+indexToRemove, 1},  // <- Removes `indexToRemove` th element from `expenses` array

            }},

        },

    )

    if err != nil {

        fmt.Println(err)

    }

    err = collection.FindOne(ctx, bson.D{}).Decode(&result)

    fmt.Println(result)

}