如何从猫鼬$ lookup集合中过滤结果

如何解决如何从猫鼬$ lookup集合中过滤结果

我想在mongodb中过滤结果如下。我使用$ lookup填充另一个集合的结果。请检查我的以下代码
下面的代码是我得到的

 {
            "_id": "5f3d563122de0730d0f6a754","barcode": "1234","productname": "Lays Packet","brandName": "Lays","productSize": "12","price": "12","quant": "12","imageurl": "http://localhost:3000/images/imageurl-1597855281050.jpg","remaining": "12","creator": "3d943b957fb5db510d824c5cbd6e8f7d","__v": 0,"source": [
                {
                    "_id": "5f3a9bbc325a074240a1a815","firstname": "test","lastname": "test","storename": "test","gst": "test","phoneNumber": 1,"email": "[e-mail]","address1": "test","address2": "test","city": "test","state": "test","country": "test","zip": "1","password": "1","usertype": 3,"unique_SHOP": "3d943b957fb5db510d824c5cbd6e8f7d","__v": 0
                }
            ]
        },

如何仅从源代码列表中检索unique_SHOP和zip。我想要的结果如下所示，其中包含一个或多个字段

 {
    "_id": "5f3d563122de0730d0f6a754","source": [
        {
             "zip": "1",}
    ]
},

我使用的查询

   List.aggregate([
    {$match:
      { productname: { $regex: req.params.query,$options: "i" }}
    },{ $lookup:{
          from: "suppliers",localField: "creator",foreignField: "unique_SHOP",as: "source"
        }
   },]) 

解决方法

您可以尝试$lookup with pipeline，

$match的
• creator id条件
• $project以显示必填字段

  {
    $lookup: {
      from: "suppliers",as: "source",let: { creator: "$creator" },pipeline: [
        {
          $match: {
            $expr: { $eq: ["$$creator","$_id"] }
          }
        },{
          $project: {
            _id: 0,zip: 1,unique_SHOP: 1
          }
        }
      ]
    }
  }

Playground