从子文档数组中获取记录，其中id从MongoDB中的234开始
要从子文档数组中获取记录，请使用$unwind和$push。对于从234开始的ID，请在MongoDB中使用regex。
让我们创建一个包含文档的集合-
> db.demo556.insertOne(
... {
... _id:101,
... details:[
... {
... id:"234336",
... Name:"Chris"
... },
... {
... id:"123456",
... Name:"Bob"
... },
... {
... id:"234987",
... Name:"Carol"
... },
... {
... id:"989768",
... Name:"David"
... },
... {
... id:"234888",
... Name:"Sam"
... },
... {
... id:"847656",
... Name:"John"
... }
... ]
... }
... );
{ "acknowledged" : true, "insertedId" : 101 }在find()方法的帮助下显示集合中的所有文档-
> db.demo556.find();
这将产生以下输出-
{ "_id" : 101, "details" : [
{ "id" : "234336", "Name" : "Chris" },
{ "id" : "123456", "Name" : "Bob" },
{ "id" : "234987", "Name" : "Carol" },
{ "id" : "989768", "Name" : "David" },
{ "id" : "234888", "Name" : "Sam" },
{ "id" : "847656", "Name" : "John" }
] }以下是从子文档数组中获取记录的查询-
> db.demo556.aggregate({
... $match: {
... "_id": 101
... }
... }, {
... $unwind: "$details"
... }, {
... $match: {
... "details.id": {
... $regex: /^234/
... }
... }
... }, {
... $group: {
... _id: "$_id",
... "Detail": {
... $push: "$details"
... }
... }
... }).pretty();这将产生以下输出-
{
"_id" : 101,
"Detail" : [
{
"id" : "234336",
"Name" : "Chris"
},
{
"id" : "234987",
"Name" : "Carol"
},
{
"id" : "234888",
"Name" : "Sam"
}
]
}