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go - 从类型 []primitive.M Go 中读取数据

问题描述

我编写代码从 MongoDB 读取数据。

输出类型是[]primitive.M

这是我的代码

func GetAllChildOfNode(node string) error {
    ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
    client, err := mongo.Connect(ctx, options.Client().ApplyURI("URI"))
    if err != nil {
        return err
    }
    defer client.Disconnect(ctx)
    database := client.Database("users")
    users := database.Collection("users")
    matchStage := bson.D{{"$match", bson.D{{"username", node}}}}
    graphStage := bson.D{{"$graphLookup", bson.D{{"from", "users"}, {"startWith", "$username"}, {"connectFromField", "userparentid"}, {"connectToField", "userparentid"}, {"as", "descendants"}}}}
    unWind := bson.D{{"$unwind", "$descendants"}}
    replaceRoot := bson.D{{"$replaceRoot", bson.D{{"newRoot", "$descendants"}}}}
    proJect := bson.D{{"$project", bson.D{{"descendants", 0}}}}
    showInfoCursor, err := users.Aggregate(ctx, mongo.Pipeline{matchStage, graphStage, unWind, replaceRoot, proJect})
    if err != nil {
        panic(err)
    }
    var showsWithInfo []bson.M
    if err = showInfoCursor.All(ctx, &showsWithInfo); err != nil {
        panic(err)
    }
    fmt.Println(showsWithInfo)
    fmt.Println("---------------------")
    fmt.Printf("%T \n", showsWithInfo)
    fmt.Println("---------------------")
    return nil
}

这是我的输出结果：

[map[_id:ObjectID("5ebd05b52f37000085002219") comdepartment:BOMON_VIENTHONG comid:DHBK lastname:SV1_BMVT password:123456 usercode:DHBK_0015 userdate:2020-05-05 useremail:SV1_BMVT@edu.com.vn username:SV1_BMVT userparentid:GV_BMVT userstatus:ACTIVE usertel:0907111015 usertype:USER_COM] map[_id:ObjectID("5ebd05b52f3700008500221a") comdepartment:BOMON_VIENTHONG comid:DHBK lastname:SV2_BMVT password:123456 usercode:DHBK_0016 userdate:2020-05-05 useremail:SV2_BMVT@edu.com.vn username:SV2_BMVT userparentid:GV_BMVT userstatus:ACTIVE usertel:0907111016 usertype:USER_COM]  map[_id:ObjectID("5ece3517b8d5570916d013f6") comdepartment:BOMON_VIENTHONG comid:DHBK lastname:SV5_BMVT password:123 usercode:DHBK_0019 userdate:2020-05-14 useremail:SV5_BMVT@edu.com.vn username:SV5_BMVT userparentid:GV_BMVT userstatus:ACTIVE usertel:0907111019 usertype:USER_COM]  map[_id:ObjectID("5ebd05b52f3700008500221b") comdepartment:BOMON_VIENTHONG comid:DHBK lastname:SV3_BMVT password:123456 usercode:DHBK_0017 userdate:2020-05-05 useremail:SV3_BMVT@edu.com.vn username:SV3_BMVT userparentid:GV_BMVT userstatus:ACTIVE usertel:0907111017 usertype:USER_COM] 
  map[_id:ObjectID("5ebd05b52f3700008500221c") comdepartment:BOMON_VIENTHONG comid:DHBK lastname:SV4_BMVT password:123456 usercode:DHBK_0018 userdate:2020-05-05 useremail:SV4_BMVT@edu.com.vn username:SV4_BMVT userparentid:GV_BMVT userstatus:ACTIVE usertel:0907111018 usertype:USER_COM]  map[_id:ObjectID("5eddf0a9b8d5570916dae6ff") comdepartment:BOMON_VIENTHONG comid:DHBK lastname:SV6_BMVT password:123456 usercode:DHBK_0019 userdate:2020-06-08 useremail:SV6_BMVT@edu.com.vn username:SV6_BMVT userparentid:GV_BMVT userstatus:ACTIVE usertel:0907111020 usertype:USER_COM]]
---------------------
[]primitive.M 
---------------------

但我现在不知道如何username仅从[]primitive.M类型中获取。例如

TRUONGKHOA_BMVT,PHOKHOA_BMVT,THUKY_BMVT,GV_BMVT,SV1_BMVT,SV2_BMVT,SV3_BMVT,SV4_BMVT,SV5_BMVT,SV6_BMVT

标签： go

解决方案

在这里总结一下答案。primitive.M只不过是一个map[string]interface{}. 所以要访问username你可以做这样的事情，

for _, s := range showsWithInfo {
    fmt.Println(s["username"])
}

在将其用作字符串之前，您可能必须先键入它

username,ok := s["username"].(string)
if !ok {
    panic("username could not be converted to string")
}

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