$lookup 嵌套对象数组

Question

我的文档有多个对象的数组，我需要找到相关的值并推入同一个数组。

购物车

{
    "_id" : ObjectId("5b2b72119fbb60750e0061b9"),
    "cartId" : "1529573905701",
    "supplierId" : ObjectId("5b221d1b63eda2902418434d"),
    "user_id" : "5b20c54651e68057b3cbe745",
    "createdAt" : ISODate("2018-06-21T09:38:25.680Z"),
    "services" : [ 
        {
            "date" : "21-06-2018",
            "timeSlot_id" : ObjectId("5b29e08cb116c31f5b1f56c6"),
            "time" : "03:30 PM - 04:30 PM",
            "serviceId" : ObjectId("5b24aff4abf2494701bc1c15"),
            "cost" : 250,
            "_id" : ObjectId("5b2b72119fbb60750e0061ba")
        }, 
        {
            "_id" : ObjectId("5b2b72329fbb60750e0061bb"),
            "cost" : 250,
            "serviceId" : ObjectId("5b24aff4abf2494701bc1c15"),
            "time" : "03:30 PM - 04:30 PM",
            "timeSlot_id" : ObjectId("5b29e08cb116c31f5b1f56c6"),
            "date" : "21-06-2018"
        }
    ],
    "__v" : 0
} 

服务

{
    "_id" : ObjectId("5b24aff4abf2494701bc1c15"),
    "isActivated" : true,
    "supplierServiceId" : 900146649,
    "serviceId" : 99473640,
    "serviceName" : "AC Reparing",
    "description" : "all type of AC, Split AC and Window AC",
    "cost" : 250,
    "serviceDuration" : "60",
    "startTime" : "07:00 AM",
    "endTime" : "08:30 PM",
    "supplierId" : "5b221d1b63eda2902418434d",
    "createdAt" : ISODate("2018-06-16T06:36:36.091Z"),
    "__v" : 0
}

时隙

{
    "_id" : ObjectId("5b29e08cb116c31f5b1f56c6"),
    "displayString" : "03:30 PM - 04:30 PM",
    "isActivated" : true,
    "startTime" : "15:30 PM",
    "endTime" : "16:30 PM",
    "duration" : "60",
    "createdAt" : ISODate("2018-06-20T05:05:16.405Z"),
    "__v" : 0
}

CART 中的服务有两个值 serviceId 和 timeSlot_id

*我需要来自相关集合的与两者相关的数据。在同一个对象内。

Mongo 版本-v3.6.5

请帮助解决这个问题。提前致谢。

Answer 1

您需要 $unwind services 以便将其 timeSlot_id 和 serviceId 与另一个 TimeSlots 集合的 _id 和 ServiceId 分别匹配...然后您可以 $group它开始“回滚”到数组中的过程。

如果你有 mongodb 版本 3.6

Cart.aggregate([
  { "$match": { "user_id": _user._id } },
  { "$unwind": "$services" },
  { "$lookup": {
    "from": TimeSlot.collection.name,
    "let": { "timeSlot_id": "$services.timeSlot_id" },
    "pipeline": [
       { "$match": { "$expr": { "$eq": [ "$_id", "$$timeSlot_id" ] } } }
     ],
     "as": "services.timeSlot_id"
  }},
  { "$lookup": {
    "from": Service.collection.name,
    "let": { "serviceId": "$services.serviceId" },
    "pipeline": [
       { "$match": { "$expr": { "$eq": [ "$_id", "$$serviceId" ] } } }
     ],
     "as": "services.serviceId"
  }},
  { "$unwind": "$services.timeSlot_id" },
  { "$unwind": "$services.serviceId" },
  { "$group": {
    "_id": "$_id",
    "services": { "$push": "$services" },
    "cartId" : { "$first": "$cartId" },
    "supplierId" : { "$first": "$supplierId" },
    "user_id" : { "$first": "$user_id" },
    "createdAt" : { "$first": "$createdAt" }
  }}
])

如果您有 3.6

之前的 mongodb 版本

Cart.aggregate([
  { "$match": { "user_id": _user._id } },
  { "$unwind": "$services" },
  { "$lookup": {
    "from": TimeSlot.collection.name,
    "localField": "services.timeSlot_id",
    "foreignField": "_id",
    "as": "services.timeSlot_id",
  }},
  { "$lookup": {
    "from": Service.collection.name,
    "localField": "services.serviceId",
    "foreignField": "_id",
    "as": "services.serviceId",
  }},
  { "$unwind": "$services.timeSlot_id" },
  { "$unwind": "$services.serviceId" },
  { "$group": {
    "_id": "$_id",
    "services": { "$push": "$services" },
    "cartId" : { "$first": "$cartId" },
    "supplierId" : { "$first": "$supplierId" },
    "user_id" : { "$first": "$user_id" },
    "createdAt" : { "$first": "$createdAt" }
  }}
])