如何在mongodb中加入兩個集合，類似於mysql中的內部加入

Question

首次收藏： transactions

{
  "_id": "QH2yYgJyE8A1zKBAWTv_T0VmvceS5l7p15Lki_i2PwfGoV3kHzkeqa6yFFm5oLhwriF39bAl2b4wgSIkvwy-MA",
  "rate": [
    {
      "user_id": ObjectId("58aeb5bd21b8ae596d3c9869"),
      "rate": "4",
      "option": "QUICK_BITE",
      "message": "Good"
    }
  ]
}

第二收藏： users

{
  "_id": ObjectId("58aeb5bd21b8ae596d3c9869"),
  "username": "ravi",
  "profile": {
    "firstname": "Ravi",
    "lastname": "Kumar",
    "email": "ravi@gamil.com",
    "phone_no": "",
    "company_name": "gmail",
    "image": ""
  }
},
{
  "_id": ObjectId("58c104da21b8aeac733c9869"),
  "username": "",
  "profile": {
    "firstname": "lalit",
    "lastname": "sharma",
    "email": "lxyz@gmail.com",
    "phone_no": "",
    "company_name": ""
  }
},
{
  "_id": ObjectId("58c12afc21b8aef8553c9869"),
  "username": "",
  "profile": {
    "firstname": "Aijaz",
    "lastname": "Haidar",
    "email": "jazhaidar@gmail.com",
    "phone_no": "",
    "company_name": "yahoo",
    "image": ""
  }
}

我想將users集合與transactions集合一起加入，這樣我就可以在費率中獲得用戶的完整個人資料詳細信息。

輸出類似

 {
    "_id" : ObjectId("58c1200321b8ae2d413c98a5"),
    "rate" : [
        {
            "rate" : "4",
            "option" : "QUICK_BITE",
            "message" : "Good",
            "profile" : {
                "firstname" : "Ravi",
                "lastname" : "Kumar",
                "email" : "ravi@gamil.com",
                "phone_no" : "",
                "company_name" : "gmail",
                "image" : ""
            }
        }
    ]
} 

現在，我通過以下方式使用$lookup合並兩個集合：

db.transactions.aggregate([ 
    {$lookup: {
           from: "users",
           localField: "rate.user_id",
           foreignField: "_id",
           as: "profile"
         }}
]);

但是上面的查詢不起作用:(

Answer 1

這對我有用

db.transactions.aggregate([
   {
      $match: { "name": "The Mean Fiddler" }
   },
    {
      $unwind: "$rate"
   },
   {
      $lookup:
         {
        from: "users",
        localField: "rate.user_id",
        foreignField: "_id", 
        as: "userInfo" 
    }
   },{$unwind:"$userInfo"},{$unwind:"$userInfo.profile"},
   {$project:{
       "_id":1,
       "rate":[{
           'rate':"$rate.rate",
           'option':"$rate.option",
           'message':"$rate.message",
           'profile' : {
               'firstname' : "$userInfo.profile.firstname",
               'lastname' :"$userInfo.profile.lastname" ,
               'email' : "$userInfo.profile.email",
               'phone_no' : "$userInfo.profile.phone_no",
               'company_name' : "$userInfo.profile.company_name",
               'image' : "$userInfo.profile.image",
           },
       }]
   }}
])