Mongo DB聚合将图书转换为作者数组
Mongo DB聚合将图书转换为作者数组
提问于 2020-02-21 15:06:27
我的藏书是这样的：
{
"book": {
"title": "Book1",
"author": "Tom"
},
"quantity": 3
},
{
"book": {
"title": "Book2",
"author": "Tom"
},
"quantity": 4
},
{
"book": {
"title": "Book3",
"author": "Dick"
},
"quantity": 9
},
{
"book": {
"title": "Book4",
"author": "Harry"
},
"quantity": 6
},
{
"book": {
"title": "Book5",
"author": "Chris"
},
"quantity": 7
},
{
"book": {
"title": "Book6",
"author": "Dick"
},
"quantity": 10
}这个集合包含有书名、作者和数量的书籍文档。
我需要帮助想出聚合，这将输出作者的数组，以及他们的书籍和数量。例如，汤姆写了"Book1“和"Book2"，”迪克“写了"Book6”和"Book3“。
authors: [
{
"name": "Tom",
"books": [
{
"title": "Book1",
"quantity": "3"
},
{
"title": "Book2",
"quantity": "4"
}
]
},
{
"name": "Dick",
"books": [
{
"title": "Book6",
"quantity": "10"
},
{
"title": "Book3",
"quantity": "9"
}
]
},
{
"name": "Harry",
"books": [
{
"title": "Book4",
"quantity": "6"
}
]
}
]回答 2
Stack Overflow用户
回答已采纳
发布于 2020-02-21 15:23:03
尝试此聚合：
db.collection.aggregate([{
$group: {
_id: "$book.author",
books: {
$push: {
title: "$book.title",
quantity: "$quantity"
}
}
}},{
$project: {
"name": "$_id",
"books": 1,
"_id": 0
}}])我在芒果游乐场上尝试过：https://mongoplayground.net/p/m-QbX-uzkkt
Stack Overflow用户
发布于 2020-02-21 15:14:56
如下所示进行尝试：
db.collection.aggregate([
{
$group: {
_id: "$book.author",
books: { $push: { "title": "$book.title", "quantity": "$quantity"} }
},
}
])输出将是
/* 1 */
{
"_id" : "Chris",
"books" : [
{
"title" : "Book5",
"quantity" : 7
}
]
},
/* 2 */
{
"_id" : "Harry",
"books" : [
{
"title" : "Book4",
"quantity" : 6
}
]
},
/* 3 */
{
"_id" : "Dick",
"books" : [
{
"title" : "Book3",
"quantity" : 9
},
{
"title" : "Book6",
"quantity" : 10
}
]
},
/* 4 */
{
"_id" : "Tom",
"books" : [
{
"title" : "Book1",
"quantity" : 3
},
{
"title" : "Book2",
"quantity" : 4
}
]
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/60333668
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