MongoDB查询在一行中显示子文档
要在一行中显示子文档，请使用$unwind和aggregate()。让我们创建一个包含文档的集合-
> db.demo183.insertOne(
... {
... "_id": "110",
... "DueDate": ISODate("2020-02-04T01:10:42.000Z"),
... "ProductDetails": [
... {
... "ProductName": "Product-1",
... "isAvailable": true
... },
... {
... "ProductName": "Product-2",
... "isAvailable": false
... }
... ]
... }
...);
{ "acknowledged" : true, "insertedId" : "110" }在find()方法的帮助下显示集合中的所有文档-
> db.demo183.find().pretty();
这将产生以下输出-
{
"_id" : "110",
"DueDate" : ISODate("2020-02-04T01:10:42Z"),
"ProductDetails" : [
{
"ProductName" : "Product-1",
"isAvailable" : true
},
{
"ProductName" : "Product-2",
"isAvailable" : false
}
]
}以下是如何查询子文档并在一行上打印-
> var productdata = function (d) {
... print(d.DueDate+", " + d.ProductDetails.ProductName + ", " + d.ProductDetails.isAvailable);
... }
> var iterator = db.demo183.aggregate([
... {$match: {_id: "110"}},
... {$unwind: '$ProductDetails'}
... ]);
> iterator.forEach(productdata );这将产生以下输出-
Tue Feb 04 2020 06:40:42 GMT+0530 (India Standard Time), Product-1, true Tue Feb 04 2020 06:40:42 GMT+0530 (India Standard Time), Product-2, false