MongoDB在同一个集合上多次查找

【问题标题】：MongoDB multiple lookup on same collectionMongoDB在同一个集合上多次查找
【发布时间】：2019-01-06 01:27:24
【问题描述】：

我有一个子集合，其中有 3 个不同的字段链接到同一个主集合。如果我将它们合并到第 3 个根元素中，则覆盖第一个 2，这是有道理的，因为所有三个 3 查找都指向同一个集合。如果我不合并这些集合，我需要遍历结果集并在客户端一一填充模型字段，这是我想避免的。

有没有办法，我可以合并所有 3 个查找结果，并且可以以某种方式更改字段名称，所以一个不会覆盖到另一个。

下面是我的代码：-

module.exports.getAssignmentByClient = function(req, res) {
var query = url.parse(req.url,true).query;

Assignment.aggregate([
    {
        $match : 
        { 
            clientId: 4, 
        } , 
    },
    {
       $lookup:
        {
            from: "staffs",
            localField: "assignedMember1",
            foreignField: "staffId",
            as: "member1"
        },            
    },
    {
        $lookup:
         {
             from: "staffs",
             localField: "assignedMember2",
             foreignField: "staffId",
             as: "member2"
         },            
    },
    {
        $lookup:
         {
             from: "staffs",
             localField: "assignedLeader",
             foreignField: "staffId",
             as: "leader"
         },            
    },
    {
        $replaceRoot: 
        { 
            newRoot: 
            { 
                $mergeObjects: [ 
                    {$arrayElemAt: [ "$member1", 0 ]}, 
                    {$arrayElemAt: [ "$member2", 0 ]}, 
                    {$arrayElemAt: [ "$leader", 0 ]}, 
                "$$ROOT" ] 
            } 
        }
    }, 
    { 
        $project: 
        { 
            member1: 0,
            member2: 0,
            leader: 0
        } 
    } 
  ],
  function (err, response) {
    if (err) throw err;
    if (!response) {
        res.status(200).json({ success: false, message: 'Somthing went wrong. Please contact admin.'});
    }
    else {
        res.status(200).json({ success: true, message: 'Successfull', data: response});
    }
  });
};

没有合并的结果集：

{
    "success": true,
    "message": "Successfull",
    "data": [
        {
            "_id": "5b5d083cf7edf20be8999746",
            "assignmentId": 25,
            "taskId": 1,
            "assignedLeader": 2,
            "assignedMember1": 1,
            "assignedMember2": 1,
            "priority": "M",
            "startDate": "2018-01-08T05:00:00.000Z",
            "endDate": "2018-09-08T04:00:00.000Z",
            "status": "R",
            "billingMode": "F",
            "fixedAmount": 12,
            "hourlyRate": 0,
            "hours": 0,
            "hourlyAmount": 0,
            "clientId": 4,
            "__v": 0,
            "member1": [
                {
                    "_id": "5b5906a66a6c614f8cb9bd99",
                    "staffId": 1,
                    "staffName": "A",
                    "designation": "E",
                    "phone": 9876,
                    "address1": "US",
                    "address2": "",
                    "email": "a@a.com",
                    "manager": "2",
                    "__v": 0
                }
            ],
            "member2": [
                {
                    "_id": "5b5906a66a6c614f8cb9bd99",
                    "staffId": 1,
                    "staffName": "B",
                    "designation": "E",
                    "phone": 9876,
                    "address1": "US",
                    "address2": "",
                    "email": "b@b.com",
                    "manager": "2",
                    "__v": 0
                }
            ],
            "leader": [
                {
                    "_id": "5b5906cb6a6c614f8cb9bd9a",
                    "staffId": 2,
                    "staffName": "C",
                    "designation": "M",
                    "phone": 2488263783,
                    "address1": "U",
                    "address2": "",
                    "email": "c@c.com",
                    "manager": "",
                    "__v": 0
                }
            ]
        }
    ]
}

带有合并的结果集：- [最后一次查找与领导者替换成员 1 和成员 2] 

{
    "success": true,
    "message": "Successfull",
    "data": [
        {
            "_id": "5b5d083cf7edf20be8999746",
            "assignmentId": 25,
            "taskId": 1,
            "assignedLeader": 2,
            "assignedMember1": 1,
            "assignedMember2": 1,
            "priority": "M",
            "startDate": "2018-01-08T05:00:00.000Z",
            "endDate": "2018-09-08T04:00:00.000Z",
            "status": "R",
            "billingMode": "F",
            "fixedAmount": 12,
            "hourlyRate": 0,
            "hours": 0,
            "hourlyAmount": 0,
            "clientId": 4,
            "__v": 0,
            "staffId": 2,
            "staffName": "C",
            "designation": "M",
            "phone": 2488263783,
            "address1": "U",
            "address2": "",
            "email": "c@c.com",
            "manager": "",
        }
    ]
}

更新代码：-

module.exports.getAssignmentByClient = function(req, res) {
var query = url.parse(req.url,true).query;

Assignment.aggregate([
    {
        $match : 
        { 
            clientId: 4, 
        } , 
    },
    {
       $lookup:
        {
            from: "staffs",
            localField: "assignedMember1",
            foreignField: "staffId",
            as: "member1"
        },            
    },
    {
        $lookup:
         {
             from: "staffs",
             localField: "assignedMember2",
             foreignField: "staffId",
             as: "member2"
         },            
    },
    {
        $lookup:
         {
             from: "staffs",
             localField: "assignedLeader",
             foreignField: "staffId",
             as: "leader"
         },            
    },
    {"$replaceRoot":{
        "newRoot":{
          "$reduce":{
            "input":[{"k":"member1","v":"$member1"},{"k":"member2","v":"$member2"},{"k":"leader","v":"$leader"}],
            "initialValue":"$$ROOT",
            "in":{
              "$mergeObjects":[
                {"$let":{
                  "vars":{"v":{"$arrayElemAt":["$$this.v",0]}},
                  "in":{"$arrayToObject":{
                    "$map":{
                      "input":{"$objectToArray":"$$v"},
                      "as":"val",
                      "in":{
                        "k":{"$concat":["$$this.k","-","$$val.k"]},
                        "v":"$$val.v"}
                    }
                  }}
                }},
                "$$value"
              ]
            }
          }
        }
    }},
    { 
        "$project": { 
            "member1": 0, 
            "member2": 0, 
            "leader": 0 
        } 
    } 
  ],
  function (err, response) {
    if (err) throw err;
    if (!response) {
        res.status(200).json({ success: false, message: 'Somthing went wrong. Please contact admin.'});
    }
    else {
        res.status(200).json({ success: true, message: 'Successfull', data: response});
    }
  });

};

带有更新代码的 JSON 结果：-

{
"success": true,
"message": "Successfull",
"data": [
    {
        "leader-_id": "5b5906cb6a6c614f8cb9bd9a",
        "leader-staffId": 2,
        "leader-staffName": "A",
        "leader-designation": "M",
        "leader-phone": 2488263783,
        "leader-address1": "US",
        "leader-address2": "",
        "leader-email": "a@a.com",
        "leader-manager": "",
        "leader-__v": 0,
        "member2-_id": "5b5906a66a6c614f8cb9bd99",
        "member2-staffId": 1,
        "member2-staffName": "B",
        "member2-designation": "E",
        "member2-phone": 9876,
        "member2-address1": "US",
        "member2-address2": "",
        "member2-email": "b@b.com",
        "member2-manager": "2",
        "member2-__v": 0,
        "member1-_id": "5b5906a66a6c614f8cb9bd99",
        "member1-staffId": 1,
        "member1-staffName": "C",
        "member1-designation": "E",
        "member1-phone": 9876,
        "member1-address1": "US",
        "member1-address2": "",
        "member1-email": "c@c.com",
        "member1-manager": "2",
        "member1-__v": 0,
        "_id": "5b5d083cf7edf20be8999746",
        "assignmentId": 25,
        "taskId": 1,
        "assignedLeader": 2,
        "assignedMember1": 1,
        "assignedMember2": 1,
        "priority": "M",
        "startDate": "2018-01-08T05:00:00.000Z",
        "endDate": "2018-09-08T04:00:00.000Z",
        "status": "R",
        "billingMode": "F",
        "fixedAmount": 12,
        "hourlyRate": 0,
        "hours": 0,
        "hourlyAmount": 0,
        "clientId": 4,
        "__v": 0
    },
    {
        "_id": "5b5e0f9ced856f17187c8888",
        "assignmentId": 28,
        "taskId": 2,
        "assignedLeader": "2",
        "assignedMember1": "1",
        "assignedMember2": "1",
        "priority": "H",
        "startDate": "2018-01-08T05:00:00.000Z",
        "endDate": "2018-07-08T04:00:00.000Z",
        "status": "C",
        "billingMode": "F",
        "fixedAmount": 900,
        "hourlyRate": 0,
        "hours": 0,
        "hourlyAmount": 0,
        "clientId": 4,
        "__v": 0
    }
]

}

嵌套集合字段引用 *（我已经嵌套查找 assignmentMaster，然后我想将此集合字段作为匹配字段引用到其他集合中，但它没有返回所需的结果。好像我是无法正确引用 assignmentMaster 字段。）

module.exports.getAssignmentByClient = function(req, res) {
var query = url.parse(req.url,true).query;
var clientId = parseInt(query.clientId);

AssignmentDetail.aggregate([
    {
        $match : 
        { 
            clientId: clientId, 
        } , 
    },
    {
        $lookup:
        {
            from: "assignmentmasters",
            localField: "assignmentId",
            foreignField: "assignmentId",
            as: "assignmentMasterData"
        },            
    },
    { 
        $lookup: {
        from: "lists",
        let: { "status": "$assignmentMasterData" },
        pipeline: [
            { 
                $match: 
                    { $expr: { $and: [ 
                        { $eq: 
                            [ "$listName", "AssignmentStatus" ] 
                        },
                        { $eq: 
                            [ "$listItem", "$$status.status" ] 
                        }
                        ]
                    }
                } 
            },
        ],
        as: "assignmentStatus"
    }},


    {"$replaceRoot":{
        "newRoot":{
          "$reduce":{
            "input":[{"k":"assignmentStatus","v":"$assignmentStatus"},{"k":"assignmentMasterData","v":"$assignmentMasterData"}],
            "initialValue":"$$ROOT",
            "in":{
              "$mergeObjects":[
                {"$let":{
                  "vars":{"v":{"$arrayElemAt":["$$this.v",0]}},
                  "in":{"$arrayToObject":{
                    "$map":{
                      "input":{"$objectToArray":"$$v"},
                      "as":"val",
                      "in":{
                        "k":{"$concat":["$$this.k","-","$$val.k"]},
                        "v":"$$val.v"}
                    }
                  }}
                }},
                "$$value"
              ]
            }
          }
        }
    }},
    { 
        "$project": { 
            "assignmentStatus": 0,
            "assignmentMasterData": 0
        } 
    } 
  ],
  function (err, response) {
    if (err) throw err;
    if (!response) {
        res.status(200).json({ success: false, message: 'Somthing went wrong. Please contact admin.'});
    }
    else {
        res.status(200).json({ success: true, message: 'Successfull', data: response});
    }
  });

};

【问题讨论】：

  • 您能发布所有集合中的示例文档吗...您的 mongodb 版本是什么？
  • 我用结果集更新了我的问题。 Mongo DB 版本是 3.6。

标签： javascript node.js mongodb npm mongoose


【解决方案1】：

您可以使用以下聚合查询为每个查找的所有键加上其别名。

使用$concat 将查找别名添加到使用$map、$objectToArray 和$arrayToObject 运算符的每个查找列的前缀。

下面显示了 member1 的示例。类似地添加所有其他查找别名。

类似

{"$replaceRoot":{
    "newRoot":{
      "$mergeObjects":[
        {"$let":{
          "vars":{"v":{"$arrayElemAt":["$member1",0]}},
          "in":{"$arrayToObject":{
            "$map":{
                "input":{"$objectToArray":"$$v"},
                "as":"val",
                "in":{
                  "k":{"$concat":["member1","-","$$val.k"]},
                  "v":"$$val.v"
                }}
          }}
        }},
       --- other look up alias here 
      ]
   }
}}

如果您不想为所有别名重复相同的代码，您可以创建一个文档数组和$reduce 来创建合并文档。

类似

{"$replaceRoot":{
  "newRoot":{
    "$reduce":{
      "input":[{"k":"member1","v":"$member1"},{"k":"member2","v":"$member2"},{"k":"leader","v":"$leader"}],
      "initialValue":"$$ROOT",
      "in":{
        "$mergeObjects":[
          {"$let":{
            "vars":{"v":{"$arrayElemAt":["$$this.v",0]}},
            "in":{"$arrayToObject":{
              "$map":{
                "input":{"$objectToArray":"$$v"},
                "as":"val",
                "in":{
                  "k":{"$concat":["$$this.k","-","$$val.k"]},
                  "v":"$$val.v"}
              }
            }}
          }},
          "$$value"
        ]
      }
    }
  }
}}

【讨论】：

  • 当我在集合分配中只有一条记录时它可以工作。如果集合有一条记录，它会起作用并将字段名称替换为成员 1、2 和领导者查找。但是如果一个集合有多个记录，它不会连接查找结果。
  • 不确定我是否理解您的评论。据我了解，连接每个作业行的所有查找记录。因此，如果有多个分配行，您应该获得多个连接的行。这不是你想要的吗？
  • 是的，你是对的。对于每个分配行，我想连接查找的结果。现在它对分配的第一行工作正常，但分配的其余行没有任何来自查找的连接行。
  • 那不应该发生。我有机会查看您的查询吗？可以添加到帖子底部吗？
  • 我已经用标签更新代码更新了代码。请查看并感谢您对此进行调查。感谢您的帮助。
【解决方案2】：

有没有办法，我可以合并所有 3 个查找结果，并且可以以某种方式更改字段名称，所以一个不会覆盖到另一个。

您可以在现有的聚合查询 (https://docs.mongodb.com/manual/reference/operator/aggregation/concatArrays/) 中使用 $concatArrays 连接数组！

试试这个代码：

module.exports.getAssignmentByClient = function(req, res) {
var query = url.parse(req.url,true).query;

Assignment.aggregate([
    {
        $match : 
        { 
            clientId: 4, 
        } , 
    },
    {
       $lookup:
        {
            from: "staffs",
            localField: "assignedMember1",
            foreignField: "staffId",
            as: "member1"
        },            
    },
    {
        $lookup:
         {
             from: "staffs",
             localField: "assignedMember2",
             foreignField: "staffId",
             as: "member2"
         },            
    },
    {
        $lookup:
         {
             from: "staffs",
             localField: "assignedLeader",
             foreignField: "staffId",
             as: "leader"
         },            
    },
    { 
        $project: { 
            items: { 
                $concatArrays: [ "$member1", "$member2", "$leader" ] 
            } 
        } 
    }
  ],
  function (err, response) {
    if (err) throw err;
    if (!response) {
        res.status(200).json({ success: false, message: 'Somthing went wrong. Please contact admin.'});
    }
    else {
        res.status(200).json({ success: true, message: 'Successfull', data: response});
    }
  });
};

希望这能解决您的问题！

【讨论】：

  • 它可以工作，但它再次将所有查找结果添加到新数组中，即项目，而不是根。我希望仅将所有查找结果添加到根目录中。感谢您的回复和调查。
猜你喜欢
  • 1970-01-01
  • 2011-09-24
  • 2020-07-17
  • 2016-06-07
  • 2019-03-17
  • 2017-06-14
  • 1970-01-01
  • 2021-07-23
相关资源
最近更新 更多
热门标签
Java Python linux javascript Mysql C# Docker 算法 前端 SpringBoot Redis Vue spring 设计模式 .net core .net kubernetes c++ 数据库 数据结构 大数据 js 机器学习 微服务 Android Go 程序员 面试 JVM ASP.net core 云原生 人工智能 后端 PHP git CSS golang k8s Nginx Django mybatis 深度学习 多线程 React 架构 devops 爬虫 云计算 Spring Boot LeetCode