使用 $lookup 和 $match 聚合搜索查询 mongodb

Question

我正在为一个我不知道如何真实的查询而苦苦挣扎......我假装做一个搜索输入，在那里我想找到一个客户并从这个客户那里获得我需要的所有信息。 我有 3 个收藏。

客户集合

{
    _id: '5e3376249110c43528f31101'
    name: 'Jhon',
    rate: '5e790595b0d727313cb56d3b',
}

费率收集

{
    _id: '5e790595b0d727313cb56d3b'
    title: 'Rate for sellers'
    margin: 10,    
}

配置集合

{
    _id: '5e7276249110c43528f21402'
    idRate: '5e790595b0d727313cb56d3b'
    maring: 8,
}

我正在执行的查询是...（我只收到来自我的应用的 searchTerm）

clienteModel.aggregate([
        //in the first stage i find the client by searchTerm that contains the Name;
        {
            $match: { 
                $or: [                   
                    { name: { '$regex': req.body.searchTerm, '$options': 'i' } },
                ]
            }
        },
        //in the second stage i would like to receive only the Rate that match with the client.rate
        {
            $lookup: {
               from: "rates",
                as: "rate",
                pipeline: [
                   {
                       $match: {
                        _id: $rate
                       }
                   }
               ]
           }
      }
        //in the third stage, i would like to bring the configs that match with client.rate
        {
            $lookup: {
                from: "configs",
                as: "config",
                pipeline: [
                    {
                        $match: {
                            idRate: $rate
                        }
                    }
                ]
            }
        }

    ])

但是这个查询不起作用，它说 $rate 没有定义...我想我不知道它是如何工作的，我该如何声明 $rate？我认为如果 cliente.rate 是 clientModel 的属性，它是定义的......请帮助

Answer 1

你可以尝试如下：

db.clienteModel.aggregate([
    {
        $match: { 
                $or: [                   
                    { name: { '$regex': req.body.searchTerm, '$options': 'i' } },
                ]
            }       
    },
    {
        $lookup: {
            from: "rate",
            let: { "rateId": "$rate" },
            pipeline: [
                {
                    $match: {
                        $expr: { $eq: ["$_id", "$$rateId"] },
                    }
                }
            ],
            as: "rateDetails"
        }
    },
    {
        $lookup: {
            from: "config",
            let: { "rateId": "$rate" },
            pipeline: [
                {
                    $match: {
                        $expr: { $eq: ["$idRate", "$$rateId"] },
                    }
                }
            ],
            as: "configDetails"
        }
    },
]);

输出：

{
    "_id" : ObjectId("5e7fb25ddc976375d3c224eb"),
    "name" : "Jhon",
    "rate" : ObjectId("5e7fb22fdc976375d3c224ea"),
    "rateDetails" : [
        {
            "_id" : ObjectId("5e7fb22fdc976375d3c224ea"),
            "title" : "Rate for sellers",
            "margin" : 10
        }
    ],
    "configDetails" : [
        {
            "_id" : ObjectId("5e7fb2a2dc976375d3c224ec"),
            "idRate" : ObjectId("5e7fb22fdc976375d3c224ea"),
            "maring" : 8
        }
    ]
}