需要使用 mgo 投影嵌套数组

Question

我使用 go lang 作为我的应用程序的后端，mongoDB 作为 database.I 我面临一个问题，我比较名称并投影 leave 数组和我也需要的内部要为 leave.Since 投影证书，我只需要来自我想使用管道和项目实现的员工结构的少量信息。

 type (
        Employee struct {
            Name               string
            Password           string
           EmailAddress       string
           Position           string
           Gender             string
           Nationality        string
           Department         string
           MaritalStatus      string
           Approvedby         string
           JoinDate           time.Time
           ConfirmationDate   time.Time
           EndDate            time.Time
            Leave             []*LeaveInfo  
        }
        LeaveInfo struct {
            Total        float64
            Id           int
            Days         float64
            From        time.Time
             To          time.Time  
            Status       string
            Certificate  []*CertificateInfo
        }
        CertificateInfo struct {
            FileName string
            FileType string
            FileSize int

        }

数据库结构如下

{
    "_id" : ObjectId("58213e14927a62f3cf04e05b"),
    "name" : "string",
    "password" : "string",
    "emailaddress" : "string",
    "position" : "string",
    "gender" : "string",
    "maritalstatus" : "string",
    "approvedby" : "string",
    "nationality" : "german",
    "department" : "account",
    "joindate" : ISODate("2016-09-19T00:00:00.000Z"),
    "confirmationdate" : Date(-62135596800000),
    "enddate" : Date(-62135596800000),
    "Leave" : [ 
        {
            "total" : 20.0,
            "id" : 0,
            "days" : 0.0,
            "type" : "",
            "from" : ISODate("2016-12-12T00:00:00.000Z"),
            "to" : ISODate("2016-12-12T00:00:00.000Z"),
            "status" : "",
            "certificate" : [
                    {
                    "filename" : "malaysia",
                    "filetype" : ".zip",
                    "filesize" : 1234
                }, 
                {
                    "filename" : "singapore",
                    "filetype" : ".zip",
                    "filesize" : 1234
                }
             ]
        }, 
        {
            "total" : 19.0,
            "id" : 1,
            "days" : 1.0,

            "from" : ISODate("2016-12-12T00:00:00.000Z"),
            "to" : ISODate("2016-12-12T00:00:00.000Z"),
            "applieddate" : ISODate("2016-11-08T02:53:38.902Z"),
            "status" : "Processing",
            "approveddate" : Date(-62135596800000),
            "certificate" : [ 
                {
                    "filename" : "germany",
                    "filetype" : ".zip",
                    "filesize" : 1234
                }, 
                {
                    "filename" : "england",
                    "filetype" : ".zip",
                    "filesize" : 1234
                }
            ]
        }, 
        {
            "total" : 18.0,
            "id" : 2,
            "days" : 1.0,
            "mdays" : 0.0,
            "type" : "annualleave",
            "daytype" : "FullDay",
            "from" : ISODate("2016-12-12T00:00:00.000Z"),
            "to" : ISODate("2016-12-12T00:00:00.000Z"),
            "applieddate" : ISODate("2016-11-08T05:36:21.579Z"),
            "status" : "Processing",
            "approveddate" : Date(-62135596800000),
            "certificate" : [
                   {
                    "filename" : "india",
                    "filetype" : ".zip",
                    "filesize" : 1234
                   }, 
                   {
                    "filename" : "france",
                    "filetype" : ".zip",
                    "filesize" : 1234
                   }
                 ]
             }
         ]
     }

我在golang中的代码如下

pipe3 := c.Pipe([]bson.M{
            {
                "$match": bson.M{

                   "name":name
                 },
            },
            {
                "$unwind": "$leave",
            },

            {
                "$project": bson.M{
                    "_id":          false,

                    "name":         1,
                    "Id":           "$leave.id",
                    "Total":        "$leave.total",
                    "Days":         "$leave.days",
                    "Status":       "$leave.status",
                },
            },
       })

这里的问题是我不知道如何检索与该特定相关的证书的所有信息leave.Please请注意，该证书是一个数组，其中至少有两个索引...

I need an output similar to this. 
                    "name":        "John",
                    "Id":           "1",
                    "Total":        "10.0",
                    "Days":         "2.0",
                    "Status":       "Process",
                    "Certificate" : [
                      {
                     "filename":"certificate1",
                     "filesize":"size1"
                     },
                    {
                        "filename":"certificate2",
                        "filesize":"size2"
                     }
                      ]


                 "name":        "John",
                "Id":           "2",
                "Total":        "8.0",
                "Days":         "2.0",
                "Status":       "Process",
                "Certificate" : [
                  {
                 "filename":"certificate1",
                 "filesize":"size1"
                 },
                {
                    "filename":"certificate2",
                    "filesize":"size2"
                 }
                  ]

这是否可能使用 project.or 是否有任何其他方法可以做到 this.Appreciate 任何 help.Please.Thanks

Answer 1

使用上面的文档结构示例，您只需通过 $project 公开 certificate，如下所示：

pipeline := []bson.M{
                {"$match": bson.M{"name":"string"}},
                {"$unwind": "$Leave"},
                {"$project": bson.M{
                        "_id":          false,
                        "name":         1,
                        "Id":           "$Leave.id",
                        "Total":        "$Leave.total",
                        "Days":         "$Leave.days",
                        "Status":       "$Leave.status",
                        "Certificate":  "$Leave.certificate"},
                },
           }
pipe := collection.Pipe(pipeline)
response := []bson.M{}
err = pipe.All(&response)

由于您已经在 Leave 上使用了 $unwind，因此每个请假申请都有单独的文件。上述聚合的输出为：

 {
  "name": "string",
  "Id": 0,
  "Total": 20,
  "Days": 0,
  "Status": "",
  "Certificate": [
    {
      "filename": "malaysia",
      "filetype": ".zip",
      "filesize": 1234
    },
    {
      "filename": "singapore",
      "filetype": ".zip",
      "filesize": 1234
    }
  ]
},
{
  "name": "string",
  "Id": 1,
  "Total": 19,
  "Days": 1,
  "Status": "Processing",
  "Certificate": [
    {
      "filename": "germany",
      "filetype": ".zip",
      "filesize": 1234
    },
    {
      "filename": "england",
      "filetype": ".zip",
      "filesize": 1234
    }
  ]
},
{
  "name": "string",
  "Id": 2,
  "Total": 18,
  "Days": 1,
  "Status": "Processing",
  "Certificate": [
    {
      "filename": "india",
      "filetype": ".zip",
      "filesize": 1234
    },
    {
      "filename": "france",
      "filetype": ".zip",
      "filesize": 1234
    }
  ]
}

其中每个请假申请都有自己与请假相关联的相应证书。

需要使用 mgo 投影嵌套数组

need to project nested array using mgo

go

mongodb

mgo