[英]Mongo $projection, can you flat a sub-document array?
我想知道是否有一種方法可以通過投影嵌套子文檔數組來“展平”,以便我可以使用它來根據類型對它的條目求和。
我的文檔是這樣的:
{ "order_id":12345, "date":8/17/2019, "payment":{ status:1, transactions:[ {type: 1, amount:200}, {type: 2, amount:250}, {type: 3, amount:50}, {type: 4, amount:50}, ] } } I would like to see if you can "flatten" it to something like this using $project: { "order_id":12345, "date":8/17/2019, "status":1, "type": 1, "amount":200 }, { "order_id":12345, "date":8/17/2019, "status":1, "type": 2, "amount":250 }, { "order_id":12345, "date":8/17/2019, "status":1, "type": 4, "amount":50 }, { "order_id":12345, "date":8/17/2019, "status":1, "type": 4, "amount":50 } }
我的主要目標是匯總類型 1 和 3 的所有交易以及類型 2 和 4 的所有交易的所有金額。
Any help would be great.
以下查詢可以獲得預期的輸出:
db.check.aggregate([
{
$unwind:"$payment.transactions"
},
{
$project:{
"_id":0,
"order_id":1,
"date":1,
"status":"$payment.status",
"type":"$payment.transactions.type",
"amount":"$payment.transactions.amount"
}
}
]).pretty()
輸出:
{
"order_id" : 12345,
"date" : "8/17/2019",
"status" : 1,
"type" : 1,
"amount" : 200
}
{
"order_id" : 12345,
"date" : "8/17/2019",
"status" : 1,
"type" : 2,
"amount" : 250
}
{
"order_id" : 12345,
"date" : "8/17/2019",
"status" : 1,
"type" : 3,
"amount" : 50
}
{
"order_id" : 12345,
"date" : "8/17/2019",
"status" : 1,
"type" : 4,
"amount" : 50
}
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