汇总MongoDB子文档字段？
您可以为此使用聚合框架。首先让我们创建一个包含文档的集合-
> db.summingSubDocumentDemo.insertOne(
... { "_id" :101, "CustomerDetails" : { "CustomerPurchase" : { "CustomerPurchaseAmount" : 2000 } } });
{ "acknowledged" : true, "insertedId" : 101 }
> db.summingSubDocumentDemo.insertOne( { "_id" :102, "CustomerDetails" : { "CustomerPurchase" : { "CustomerPurchaseAmount" : 3000 } } });
{ "acknowledged" : true, "insertedId" : 102 }
> db.summingSubDocumentDemo.insertOne( { "_id" :103, "CustomerDetails" : { "CustomerPurchase" : { "CustomerPurchaseAmount" : 5000 } } });
{ "acknowledged" : true, "insertedId" : 103 }以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.summingSubDocumentDemo.find().pretty();
这将产生以下输出-
{
"_id" : 101,
"CustomerDetails" : {
"CustomerPurchase" : {
"CustomerPurchaseAmount" : 2000
}
}
}
{
"_id" : 102,
"CustomerDetails" : {
"CustomerPurchase" : {
"CustomerPurchaseAmount" : 3000
}
}
}
{
"_id" : 103,
"CustomerDetails" : {
"CustomerPurchase" : {
"CustomerPurchaseAmount" : 5000
}
}
}这是汇总MongoDB子文档字段的查询-
> db.summingSubDocumentDemo.aggregate({$group : {_id: "",
... totalAmount : {$sum: "$CustomerDetails.CustomerPurchase.CustomerPurchaseAmount"}}},
... {$project: {_id: 0, totalAmount: 1}});这将产生以下输出-
{ "totalAmount" : 10000 }