我在收集酒店有复杂的文件，我想只投影酒店名称，_id，城市和特定酒店的标准间，豪华套房和套房，我该怎么做。
这是我的文件
{
"_id" : ObjectId("59f9b27970bc1d12048e323f"),
"type" : "variable",
"country" : "Uae",
"city" : "Dubai",
"rating" : "3 star",
"name" : "taj",
"rooms" : [
{
"roomNo" : "12",
"type" : "Standard",
"maxOccupancy" : "3",
"reserved" : [
{
"from" : "2017-12-06",
"to" : "2017-12-08"
}
],
"mealPlan" : [
{
"type" : "AP",
"perDblRoom" : "10,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "17,355",
"season" : "high"
},
{
"type" : "AP",
"perDblRoom" : "9,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "6,355",
"season" : "low"
},
{
"type" : "CAP",
"perDblRoom" : "10,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "17,355",
"season" : "high"
},
{
"type" : "CAP",
"perDblRoom" : "9,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "6,355",
"season" : "low"
}
]
},
{
"roomNo" : "10",
"type" : "Deluxe",
"maxOccupancy" : "6",
"reserved" : [
{
"from" : "2017-12-09",
"to" : "2017-12-12"
},
{
"from" : "2017-12-13",
"to" : "2017-12-16"
},
{
"from" : "2017-12-18",
"to" : "2017-12-20"
}
],
"mealPlan" : [
{
"type" : "AP",
"perDblRoom" : "10,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "17,355",
"season" : "high"
},
{
"type" : "AP",
"perDblRoom" : "9,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "6,355",
"season" : "low"
},
{
"type" : "CAP",
"perDblRoom" : "10,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "17,355",
"season" : "high"
},
{
"type" : "CAP",
"perDblRoom" : "9,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "6,355",
"season" : "low"
}
]
},
{
"roomNo" : "8",
"type" : "Suite",
"maxOccupancy" : "6",
"reserved" : [
{
"from" : "2017-12-09",
"to" : "2017-12-12"
},
{
"from" : "2017-12-13",
"to" : "2017-12-14"
},
{
"from" : "2017-12-18",
"to" : "2017-12-20"
}
],
"mealPlan" : [
{
"type" : "AP",
"perDblRoom" : "10,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "17,355",
"season" : "high"
},
{
"type" : "AP",
"perDblRoom" : "9,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "6,355",
"season" : "low"
},
{
"type" : "CAP",
"perDblRoom" : "10,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "17,355",
"season" : "high"
},
{
"type" : "CAP",
"perDblRoom" : "9,334",
"extraPaxWithBed" : "3,953",
"extraPaxChildWithBed" : "3,953",
"extraPaxChildNoBed" : "2,682",
"perSglRoom" : "6,355",
"season" : "low"
}
]
}
]
}
我想要的输出应该是
{
"_id" : ObjectId("59f9b27970bc1d12048e323f"),
"name" : "taj",
"rating" : "3 star",
"city" : "Dubai",
"standard" : 4, // count of standard rooms in the hotel
"deluxe" : 4,
"suite" : 4
},{
"_id" : ObjectId("59f9b27970bc1d12048e3233"),
"name" : "hyatt",
"rating" : "3 star",
"city" : "Dubai",
"standard" : 4, // count of standard rooms in the hotel
"deluxe" : 4,
"suite" : 4
}
这是我需要从酒店集合中输出的输出，我在mongodb文档中阅读很多，并且遇到了像展开项目和组这样的方法，但无法找到输出的方法
查询：
Hotel.aggregate(
[{
"$project": {
"top": {
"_id": "$_id",
"name": "$name",
"rating": "$rating",
"city": "$city"
},
"rooms": 1
}
},
{
"$unwind": "$rooms"
},
{
"$group": {
"_id": {
"id": "$_id",
"type": "$rooms.type"
},
"count": {
"$sum": 1
},
"top": {
"$first": "$top"
}
}
},
{
"$sort": {
"_id.type": 1
}
},
{
"$group": {
"_id": "$_id.id",
"top": {
"$first": "$top"
},
"typeandcount": {
"$push": {
"k": "$_id.type",
"v": "$count"
}
},
}
},
{"$replaceRoot":{
"newRoot":{
"$arrayToObject":{
"$concatArrays":[
{"$objectToArray":"$top"},
"$typeandcount"
]
}
}
}}
]
)
答案 0 :(得分：0)
您可以在3.6版本中尝试以下聚合。
添加要保留在输出响应中的所有顶部字段。首先$group创建计数类型的酒店类型和第二组创建类型和计数值对的数组，然后$mergeObjects将顶部键值与$arrayToObject合并，生成类型键和计数值对，以生成预期的响应。
$replaceRoot将文档提升到最高级别。
db.colname.aggregate([
{"$project":{
"top":{"_id":"$_id","name":"$name","rating":"$rating","city":"$city"},
"rooms":1
}},
{"$unwind":"$rooms"},
{"$group":{
"_id":{"id":"$_id","type":"$rooms.type"},
"count":{"$sum":1},
"top":{"$first":"$top"}
}},
{"$group":{
"_id":"$_id.id",
"top":{"$first":"$top"},
"typeandcount":{"$push":{"k":"$_id.type","v":"$count"}}
}},
{"$replaceRoot":{
"newRoot":{"$mergeObjects":["$top",{"$arrayToObject":"$typeandcount"}]}
}}
])
3.4
用
替换最后阶段{"$replaceRoot":{
"newRoot":{
"$arrayToObject":{
"$concatArrays":[
{"$objectToArray":"$top"},
"$typeandcount"
]
}
}
}}