Question

此问题是关于此堆栈question的。

我正在尝试将用户数据添加到用户类型，然后将其与与贷款类型一起添加的贷款一起添加。我该如何实现？

我有以下数据集。

db={

  loans:[
    {
      loanId : ObjectId("123123123123"),
      loanAmount: 1000,
      loanType : 1,
      userId: 12
    } ,{
      loanId : ObjectId("123123123123"),
      loanAmount: 300,
      loanType : 2,
      userId: 12
    }
  ],
  loanType:[
      {_id:ObjectId("12312312"),
        loanTypeId : 1,
        type : "Home Loan"
      },{_id:ObjectId("12312313"),
        loanTypeId : 2,
        type : "Bike Loan"
      }
      ],
  User: [
    {
      _id: ObjectId("59a504eb6171b554c02292a9"),
      "userName": "Shahabaz Shafi",
      "dateOfBirth": "1992-01-01",
      userId: 12,
      userType: 1,
      "addres": {
        "country": "India",
        "state": "Karnataka",
        "city": "Bengaluru"
      }
    }
  ],
  UserType:[
      {_id:ObjectId("1233212334"),userTypeId:1, type:'student'},
      {_id:ObjectId("1233212334"),userTypeId:1, type:'staff' }
      ]
}

期望从上述数据集中获得平坦输出

输出：

{
      _id: ObjectId("59a504eb6171b554c02292a9"),
      "userName": "Shahabaz Shafi",
      "dateOfBirth": "1992-01-01",
      userId: 12,
      userType: 1,
      userTypeName : 'student',

      "addres": {
        "country": "India",
        "state": "Karnataka",
        "city": "Bengaluru"
      }

      loans : [
          {
            loanId : ObjectId("123123123123"),
            loanAmount: 1000,
            loanType : 1,
            type : "Home Loan",
            userId: 12,
          } ,{
            loanId : ObjectId("123123123123"),
            loanAmount: 300,
            loanType : 2,
            type : "Bike Loan",
            userId: 12
          }

      ]
}

我尝试了$ lookup，但是它创建了一个单独的数组而不是一个数组。

Answer 1

   /* Collection 1 : users */

        {
            "_id" : ObjectId("5c46eaf2e166363e18d6ef91"),
            "userName" : "Shahabaz Shafi",
            "dateOfBirth" : "1992-01-01",
            "userId" : 12,
            "userType" : 1,
            "addres" : {
                "country" : "India",
                "state" : "Karnataka",
                "city" : "Bengaluru"
            }
        }

        /* Collection 2 : userTypes */    
        /* 1 */
        {
            "_id" : ObjectId("5c46eb46e166363e18d6ef92"),
            "userTypeId" : 1,
            "type" : "student"
        }

        /* 2 */
        {
            "_id" : ObjectId("5c46eb46e166363e18d6ef93"),
            "userTypeId" : 2,
            "type" : "staff"
        }

        /* Collection 3 : loans */
        /* 1 */
        {
            "_id" : ObjectId("5c46eb8be166363e18d6ef94"),
            "loanAmount" : 1000,
            "loanType" : 1,
            "userId" : 12
        }

        /* 2 */
        {
            "_id" : ObjectId("5c46eb8be166363e18d6ef95"),
            "loanAmount" : 300,
            "loanType" : 2,
            "userId" : 12
        }

        /* Collection 4 : loanType */
        /* 1 */
        {
            "_id" : ObjectId("5c46ebc1e166363e18d6ef96"),
            "loanTypeId" : 1,
            "type" : "Home Loan"
        }

        /* 2 */
        {
            "_id" : ObjectId("5c46ebc1e166363e18d6ef97"),
            "loanTypeId" : 2,
            "type" : "Bike Loan"
        }

    Solution: 

    db.users.aggregate([
        {
            // Join collections users and usertypes 
            $lookup : {
                from: "userTypes",
                localField: "userType",
                foreignField: "userTypeId",
                as: "userTypes"
            }
        },
        {
          // Merge keys of array of objects userTypes in existing document
          $replaceRoot: { newRoot: { $mergeObjects: [ { $arrayElemAt: [ "$userTypes", 0 ] }, "$$ROOT" ] } }
        },
        {
            // Remove keys userTypes and userTypeId
            $project : {
                    "userTypes": 0,
                    "userTypeId" : 0
                }
        },
        {
            // Join current document obtained with loans collection
            $lookup : {
                from: "loans",
                localField: "userId",
                foreignField: "userId",
                as: "loans"
            }
        },
        {
            // Break array obtained from loans into separate documents
            $unwind : "$loans"
        },
        {
            // Join current documents obtained with loanType collection
            $lookup : {
                from: "loanType",
                localField: "loans.loanType",
                foreignField: "loanTypeId",
                as: "loanTypes"
            }
         },
         {
             // Break array obtained from loans into separate documents
             $unwind: "$loanTypes"
         },
         {
          // Display fields as per requirement and modify fields accordingly
           $project : {
                _id:"$_id",
                 "type" :1,
                "userName" : 1,
                "dateOfBirth" : 1,
                "userId" : 1,
                "userType" : 1,
                "addres" : 1,
                "loanAmount" : "$loans.loanAmount",
                "loantype": "$loans.loanType",
                "loanTypeName" : "$loanTypes.type",
               "loanId" : "$loans._id"

           }
        },
        {
           // Merge documents based on condition given and push data in loans array as per output required
           $group:{
                _id : "$_id",
               "type" : {"$first" :"$type" },
                "userName" : {"$first" :"$userName" },
                "dateOfBirth" : {"$first" :"$dateOfBirth" },
                "userId" : {"$first" :"$userId" },
                "userType" : {"$first" :"$userType" },
                "addres" : {"$first" :"$addres" },
                "loans":{
                    $push:{
                        "loanAmount" : "$loanAmount",
                        "loanType" : "$loantype",
                        "type" : "$loanTypeName",
                        "loanId" : "$loanId"
                    }
                }
            }
        }    
    ]);

    Output:

    /* 1 */
    {
        "_id" : ObjectId("5c46eaf2e166363e18d6ef91"),
        "type" : "student",
        "userName" : "Shahabaz Shafi",
        "dateOfBirth" : "1992-01-01",
        "userId" : 12,
        "userType" : 1,
        "addres" : {
            "country" : "India",
            "state" : "Karnataka",
            "city" : "Bengaluru"
        },
        "loans" : [ 
            {
                "loanAmount" : 1000,
                "loanType" : 1,
                "type" : "Home Loan",
                "loanId" : ObjectId("5c46eb8be166363e18d6ef94")
            }, 
            {
                "loanAmount" : 300,
                "loanType" : 2,
                "type" : "Bike Loan",
                "loanId" : ObjectId("5c46eb8be166363e18d6ef95")
            }
        ]
    }

@Anthony Winzlet @Shahabaz Please try this.

Mongo加入特定列

1 个答案: