获取MongoDB集合中所有具有“ isMarried”状态的嵌入式文档
要获取所有嵌入式文档，请在MongoDB中使用$project。让我们创建一个包含文档的集合-
> db.demo220.insertOne({
... "id":101,
... "FullName" : "John Doe",
... "EmailId" : "john12@gmail.com",
... "ShippingDate" : new ISODate(),
... "details" : { "_id" :1001, "isMarried" :true }
...}
...);
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3eaf5b03d395bdc213471d")
}
> db.demo220.insertOne(
...{
... "id":102,
... "FullName" : "John Smith",
... "EmailId" : "johnsmith@gmail.com",
... "ShippingDate" : new ISODate(),
... "details" : { "_id" :1002, "isMarried" :false }
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3eaf5c03d395bdc213471e")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo220.find();
这将产生以下输出-
{ "_id" : ObjectId("5e3eaf5b03d395bdc213471d"), "id" : 101, "FullName" : "John Doe", "EmailId" : "john12@gmail.com", "ShippingDate" : ISODate("2020-02-08T12:53:47.876Z"), "details" : { "_id" : 1001, "isMarried" : true } }
{ "_id" : ObjectId("5e3eaf5c03d395bdc213471e"), "id" : 102, "FullName" : "John Smith", "EmailId" : "johnsmith@gmail.com", "ShippingDate" : ISODate("2020-02-08T12:53:48.991Z"), "details" : { "_id" : 1002, "isMarried" : false } }以下是获取所有嵌入式文档的查询-
> db.demo220.aggregate({ $project : {
... "isMarried" : "$details.isMarried",
... "detailsId" : "$details_id", } });这将产生以下输出-
{ "_id" : ObjectId("5e3eaf5b03d395bdc213471d"), "isMarried" : true }
{ "_id" : ObjectId("5e3eaf5c03d395bdc213471e"), "isMarried" : false }