具有嵌套对象数组的 MongoDB 聚合
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【中文标题】具有嵌套对象数组的 MongoDB 聚合【英文标题】：MongoDB aggregation with nested arrays of objects 【发布时间】：2020-04-23 14:35:50 【问题描述】：我正在努力从 Mongo DB 中获取一些汇总数据。我有以下收藏：
餐厅：
"_id" : ObjectId("5e0ff6d424f9fc12bc3d9464"),
"name" : "Pizzaria Don Juan",
"active" : true,
"users" : [
"_id" : ObjectId("5e10fc2adc147a373c312144")
,
"_id" : ObjectId("5e11ff8003eb832ef84342a6")
],
"socialMedias" : [
"_id" : ObjectId("5e1008943330ad05d4e1867c"),
"url" : "https://instagram/jetpizzas"
,
"_id" : ObjectId("5e10089a3330ad05d4e1867d"),
"url" : "https://facebook.com/jetpizzas"
],
"branches" : [
"name" : "Teste"
,
"name" : "Teste 2"
],
"sections" : [
"name" : "Bebidas"
],
"__v" : 0
"_id" : ObjectId("5e0ffd23991918424c8d7c3b"),
"name" : "Pizza Ruth",
"active" : true,
"users" : [ ],
"socialMedias" : [ ],
"branches" : [ ],
"sections" : [ ],
"__v" : 0
"_id" : ObjectId("5e0ffd3d991918424c8d7c3c"),
"name" : "Feijão de Corda",
"active" : true,
"users" : [ ],
"socialMedias" : [ ],
"branches" : [ ],
"sections" : [ ],
"__v" : 0
用户
"_id" : ObjectId("5e10fc2adc147a373c312144"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" : 2,
"active" : true,
"username" : "contato@pizzariadonjuan.com.br",
"password" : "$2a$10$xhmw83QXbMvSqmrKAUYn.O4fOxboEyVkVB0DGkSsJUOp7K4bYQkCm",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-04T20:57:14.634Z"),
"__v" : 0
"_id" : ObjectId("5e11ff8003eb832ef84342a6"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" : 2,
"active" : true,
"username" : "sac@pizzariadonjuan.com.br",
"password" : "$2a$10$wby3cs89jyO0HUbEiGLKye0jOB3U295zzIsu8xGJ4wnQtw5jcvSZO",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-05T15:23:44.386Z"),
"__v" : 0
"_id" : ObjectId("5e11ff9c03eb832ef84342a7"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" : 2,
"active" : true,
"username" : "juan@pizzariadonjuan.com.br",
"password" : "$2a$10$nEM3RxEjYbI77R9vOWUrMOGeHFDmdZqVKUNtTLuKZVLNQBQqIbew.",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-05T15:24:12.456Z"),
"__v" : 0
个人资料
"_id" : ObjectId("5e0ea5f6832df0473cacacda"),
"number" : 1,
"name" : "Cliente",
"__v" : 0
"_id" : ObjectId("5e0ea5ff832df0473cacacdb"),
"number" : 2,
"name" : "Restaurante",
"__v" : 0
"_id" : ObjectId("5e0ea607832df0473cacacdc"),
"number" : 0,
"name" : "Admin",
"__v" : 0
和社交媒体：
"_id" : ObjectId("5e1008943330ad05d4e1867c"),
"name" : "Instagram",
"__v" : 0
"_id" : ObjectId("5e10089a3330ad05d4e1867d"),
"name" : "Facebook",
"__v" : 0
"_id" : ObjectId("5e1009043330ad05d4e1867f"),
"name" : "LinkedIn",
"__v" : 0
我的目标是获取与餐厅对象相关的所有对象。使用以下代码：
db.restaurants.aggregate([
$lookup: from: "users", localField: "users._id", foreignField: "_id", as: "foundUsers" ,
$group:
'_id': '$_id',
'name': "$first": "$name" ,
'active': "$first": "$active" ,
users: $push: '$foundUsers' ,
branches: "$first": "$branches" ,
sections: "$first": "$sections" ,
socialMedias: "$first": "$socialMedias"
,
$unwind: '$users',
$unset: 'users.password' ,
$lookup: from: "profiles", localField: "users.profile", foreignField: "number", as: "profile" ,
$addFields: 'users.profile': $arrayElemAt: ['$profile', 0] ,
$unset: 'profile' ,
$lookup: from: "socialmedias", localField: "socialMedias._id", foreignField: "_id", as: "socialMedia" ,
$addFields: 'socialMedias.name': $arrayElemAt: ['$socialMedia.name', 0] ,
$group:
'_id': '$_id',
'name': "$first": "$name" ,
'active': "$first": "$active" ,
users: $first: '$users' ,
branches: "$first": "$branches" ,
sections: "$first": "$sections" ,
socialMedias: "$first": "$socialMedias"
])
我明白了：
"_id" : ObjectId("5e0ffd3d991918424c8d7c3c"),
"name" : "Feijão de Corda",
"active" : true,
"users" : [ ],
"branches" : [ ],
"sections" : [ ],
"socialMedias" : [ ]
"_id" : ObjectId("5e0ffd23991918424c8d7c3b"),
"name" : "Pizza Ruth",
"active" : true,
"users" : [ ],
"branches" : [ ],
"sections" : [ ],
"socialMedias" : [ ]
"_id" : ObjectId("5e0ff6d424f9fc12bc3d9464"),
"name" : "Pizzaria Don Juan",
"active" : true,
"users" : [
"_id" : ObjectId("5e10fc2adc147a373c312144"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" :
"_id" : ObjectId("5e0ea5ff832df0473cacacdb"),
"number" : 2,
"name" : "Restaurante",
"__v" : 0
,
"active" : true,
"username" : "contato@pizzariadonjuan.com.br",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-04T20:57:14.634Z"),
"__v" : 0
,
"_id" : ObjectId("5e11ff8003eb832ef84342a6"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" :
"_id" : ObjectId("5e0ea5ff832df0473cacacdb"),
"number" : 2,
"name" : "Restaurante",
"__v" : 0
,
"active" : true,
"username" : "sac@pizzariadonjuan.com.br",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-05T15:23:44.386Z"),
"__v" : 0
],
"branches" : [
"name" : "Teste"
,
"name" : "Teste 2"
],
"sections" : [
"name" : "Bebidas"
],
"socialMedias" : [
"_id" : ObjectId("5e1008943330ad05d4e1867c"),
"url" : "https://instagram/jetpizzas",
"name" : "Instagram"
,
"_id" : ObjectId("5e10089a3330ad05d4e1867d"),
"url" : "https://facebook.com/jetpizzas",
"name" : "Instagram"
]
请注意，嵌套数组 socialMedias 的社交媒体名称值错误（重复的“Instagram”名称，它应该是 Instagram 的一条记录和 Facebook 的另一条记录）。即使我尝试从餐厅集合中展开 socialMedias 数组，它也只返回具有社交媒体值的餐厅对象。
有什么线索可以解决这个问题吗？
【问题讨论】：
【参考方案1】：您将$lookup 结果与现有数组合并的方式是这里的一个问题。你不能跑：
$addFields: 'socialMedias.name': $arrayElemAt: ['$socialMedia.name', 0] ,
因为你总是会得到第一个数组元素。您需要使用 $map 、 $filter 和 $mergeObjects 合并两个数组：
$addFields:
socialmedias:
$map:
input: "$socialMedias",
as: "sm",
in:
$mergeObjects: [
"$$this",
$arrayElemAt: [ $filter: input: "$socialmedias", cond: $eq: [ "$$sm.number", "$$this._id" ] , 0 ]
]
您还需要将其应用于user.profile，因为当前的解决方案容易出错。
Mongo Playground
【讨论】：
【参考方案2】：非常感谢您的帮助。我试过这个查询：
db.restaurants.aggregate([
$lookup: from: "users", localField: "users._id", foreignField: "_id", as: "foundUsers" ,
$group:
'_id': '$_id',
'name': "$first": "$name" ,
'active': "$first": "$active" ,
users: $push: '$foundUsers' ,
branches: "$first": "$branches" ,
sections: "$first": "$sections" ,
socialMedias: "$first": "$socialMedias"
,
$unwind: '$users',
$unset: 'users.password' ,
$lookup: from: "profiles", localField: "users.profile", foreignField: "number", as: "profile" ,
$addFields: 'users.profile': $arrayElemAt: ['$profile', 0] ,
$unset: 'profile' ,
$lookup: from: "socialmedias", localField: "socialMedias._id", foreignField: "_id", as: "foundSocialMedia" ,
$addFields:
socialMedias:
$map:
input: "$socialMedias",
as: "sm",
in:
$mergeObjects: [
"$$sm",
$arrayElemAt: [
$filter:
input: "$foundSocialMedia",
cond:
$eq: [
"$$sm._id",
"$$this._id"
]
,
0
]
]
,
$unset: 'foundSocialMedia' ,
])
我得到了这个想要的结果：
"_id" : ObjectId("5e0ffd3d991918424c8d7c3c"),
"name" : "Feijão de Corda",
"active" : true,
"users" : [ ],
"branches" : [ ],
"sections" : [ ],
"socialMedias" : [ ]
"_id" : ObjectId("5e0ffd23991918424c8d7c3b"),
"name" : "Pizza Ruth",
"active" : true,
"users" : [ ],
"branches" : [ ],
"sections" : [ ],
"socialMedias" : [ ]
"_id" : ObjectId("5e0ff6d424f9fc12bc3d9464"),
"name" : "Pizzaria Don Juan",
"active" : true,
"users" : [
"_id" : ObjectId("5e10fc2adc147a373c312144"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" :
"_id" : ObjectId("5e0ea5ff832df0473cacacdb"),
"number" : 2,
"name" : "Restaurante",
"__v" : 0
,
"active" : true,
"username" : "contato@pizzariadonjuan.com.br",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-04T20:57:14.634Z"),
"__v" : 0
,
"_id" : ObjectId("5e11ff8003eb832ef84342a6"),
"isExpired" : false,
"isBlocked" : false,
"loginTentatives" : 0,
"profile" :
"_id" : ObjectId("5e0ea5ff832df0473cacacdb"),
"number" : 2,
"name" : "Restaurante",
"__v" : 0
,
"active" : true,
"username" : "sac@pizzariadonjuan.com.br",
"email" : "",
"phone" : "",
"createdAt" : ISODate("2020-01-05T15:23:44.386Z"),
"__v" : 0
],
"branches" : [
"name" : "Teste"
,
"name" : "Teste 2"
],
"sections" : [
"name" : "Bebidas"
],
"socialMedias" : [
"_id" : ObjectId("5e1008943330ad05d4e1867c"),
"url" : "https://instagram/jetpizzas",
"name" : "Instagram",
"__v" : 0
,
"_id" : ObjectId("5e10089a3330ad05d4e1867d"),
"url" : "https://facebook.com/jetpizzas",
"name" : "Facebook",
"__v" : 0
]
【讨论】：
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