[英]How to use mongodb aggregation to transform document in nested array
我的文档如下图所示,我想使用聚合对其进行转换。 在favourite_products内部,我具有产品数组,并且具有与每个商店相对应的product_id。 现在,我只想要所有商店的产品ID,但要根据时间进行排序。 :
"favourite_products": [
{
"shop": {
"shop_id": "59465888f7babb000485574b",
"time": "2017-07-12T06:11:19.817Z"
},
"product": [
{
"product_id": "594c2d56f7afcf00043b1195",
"time": "2017-07-12T06:10:36.775Z"
},
{
"product_id": "594ac36c76de720004e819f6",
"time": "2017-07-12T06:11:19.817Z"
}
]
},
{
"shop": {
"shop_id": "593acc24a2902d0004211f1f",
"time": "2017-07-12T06:12:59.372Z"
},
"product": [
{
"product_id": "594ac36c76de720004e819f6",
"time": "2017-07-12T06:12:59.372Z"
}
]
}
]
我想将其转换为:
"favourite_products"
["59465888f7babb000485574b",594c2d56f7afcf00043b1195","594ac36c76de720004e819f6","593acc24a2902d0004211f1f","594ac36c76de720004e819f6"]
下面返回的时间顺序是favourite_products.product.product_id的订购文件
如果您希望结果作为不同的文档,请使用项目。 如果希望将结果作为一个文档中的数组,请使用group。
db['testing-aggregate'].aggregate([
{$unwind:'$favourite_products'},
{$unwind:'$favourite_products.product'},
{$sort:{'favourite_products.product.time':1}}, // order by time. 1=ascending | -1=descending
// {$project:{
// '_id':0, // exclude _id from output
// 'favourite_products':'$favourite_products.product.product_id' // return only product_id
// }},
{$group:{
_id:null,
product_id:{$push:'$favourite_products.product.product_id'}
}}
])
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