在 Mongoose 中使用连接和过滤器进行查询

Posted 2023-03-11

【中文标题】在 Mongoose 中使用连接和过滤器进行查询

【英文标题】：Querying with joins & filters in Mongoose

【发布时间】：2017-02-19 15:36:39

【问题描述】：

我是 Mongodb 的新手，我在使用 MEAN 堆栈构建的 Web 应用程序中使用它。我的目标是通过加入两个表并对它们应用过滤条件来查询它们。例如：我有两张表 - Bike-BikeID,Registration No.,Make,Model & Appointment - Appointment Date,Status,Bike(ref Bike object) 我只想显示那些没有预约状态的自行车= '预订'。我想在 Mongoose 中完成以下 SQL。

Select bike.* from Bike inner join Appointment on Bike.BikeID = Appointment.BikeID and Appointment.Status != 'Booked'

我正在使用以下代码，但没有得到想要的结果。有人可以帮我解决这个问题。

app.get('/api/getbikeappo*',function(req,res)
        var msg="";
        //.find(cust:req.query._id)
        //.populate('cust','email')
        ubBike.aggregate([
                
                    $match:
                    
                        cust : req.query._id
                    
                ,
                
                    $lookup:
                    
                        from: "appos",
                        localField: "_id",
                        foreignField: "bike",
                        as : "appointments"
                    
                ,
                
                    $match:
                    
                        "appointments" : $eq : []
                    
                
            ])
            .exec(function(err,bikes)
                 res.send(bikes);
                if(err) throw err;
            );
    ); 

---

bikes - collection

    "_id": 
        "$oid": "57fb600fdd9070681de19c18"
    ,
    "brand": "Splendor",
    "model": "Splendor",
    "year": "2002",
    "kms": 0,
    "regno": "TN02M8937",
    "cust": 
        "$oid": "57f8c44466cab97c1355a09a"
    ,
    "__v": 0


    "_id": 
        "$oid": "57fb6025dd9070681de19c19"
    ,
    "brand": "Activa",
    "model": "Activa",
    "year": "2016",
    "kms": 0,
    "regno": "TN14M3844",
    "cust": 
        "$oid": "57f8c44466cab97c1355a09a"
    ,
    "__v": 0


appointment collection
----------------------

    "_id": 
        "$oid": "57fb6040dd9070681de19c1a"
    ,
    "appoidt": 
        "$date": "2016-10-15T18:30:00.000Z"
    ,
    "reqdt": 
        "$date": "2016-10-10T09:32:48.694Z"
    ,
    "status": "Booked",
    "bike": 
        "$oid": "57fb600fdd9070681de19c18"
    ,
    "cust": 
        "$oid": "57f8c44466cab97c1355a09a"
    ,
    "__v": 0

-----------------
Expected output is 


    "_id": 
        "$oid": "57fb6025dd9070681de19c19"
    ,
    "brand": "Activa",
    "model": "Activa",
    "year": "2016",
    "kms": 0,
    "regno": "TN14M3844",
    "cust": 
        "$oid": "57f8c44466cab97c1355a09a"
    ,
    "__v": 0

【问题讨论】：

发布您的文档样本以及您期望的输出？

@ClementAmarnath 完成

【参考方案1】：

你快到了，你只需要正确的 $match 查询如下：

ubBike.aggregate([
     "$match":  "cust": req.query._id  ,
    
        "$lookup": 
            "from": "appos",
            "localField": "_id",
            "foreignField": "bike",
            "as": "appointments"
        
    ,
     "$match":  "appointments.status":  "$ne": "Booked"   
]).exec(function(err, bikes)
    if(err) throw err;
    res.send(bikes);    
);