如何根据数组中匹配对象的数量在 MongoDB 中查找文档?
mongodbdatabasebig data analytics更新于 2026/1/6 12:37:17
让我们看一个例子，并创建一个包含文档的集合 −
> db.demo694.insertOne(
... {
... "details" :
... [
... {
... "Name" : "Chris",
... Age:21
... },
... {
... "Name" : "David",
... Age:22
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea59279ece4e5779399c07f")
}
> db.demo694.insertOne(
... {
... "details" :
... [
... {
... "Name" : "Bob",
... Age:21
... },
... {
... "Name" : "Mike",
... Age:23
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea5927aece4e5779399c080")
}
> db.demo694.insertOne(
... {
... "details" :
... [
... {
... "Name" : "Chris",
... Age:21
... },
... {
... "Name" : "Carol",
... Age:22
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea5927aece4e5779399c081")
}
借助 find() 方法显示集合中的所有文档 −
> db.demo694.find();
这将产生以下输出 −
{ "_id" : ObjectId("5ea59279ece4e5779399c07f"), "details" : [ { "Name" : "Chris", "Age" : 21 }, { "Name" : "David", "Age" : 22 } ] }
{ "_id" : ObjectId("5ea5927aece4e5779399c080"), "details" : [ { "Name" : "Bob", "Age" : 21 }, { "Name" : "Mike", "Age" : 23 } ] }
{ "_id" : ObjectId("5ea5927aece4e5779399c081"), "details" : [ { "Name" : "Chris", "Age" : 21 }, { "Name" : "Carol", "Age" : 22 } ] }
以下是根据数组中匹配对象的数量在 MongoDB 中查找文档的查询 −
> nameChrisAge21= function () {
... var inc = 0;
... this.details.forEach(function (d) {
... if (d.Name == "Chris" && d.Age == 21) {
... inc= inc + 1;
... }
... });
... if (inc >= 1) {
... return true;
... }
... }
function () {
var inc = 0;
this.details.forEach(function (d) {
if (d.Name == "Chris" && d.Age == 21) {
inc= inc + 1;
}
});
if (inc >= 1) {
return true;
}
}
> db.demo694.find({$where:nameChrisAge21});
这将产生以下输出 −
{ "_id" : ObjectId("5ea59279ece4e5779399c07f"), "details" : [ { "Name" : "Chris", "Age" : 21 }, { "Name" : "David", "Age" : 22 } ] }
{ "_id" : ObjectId("5ea5927aece4e5779399c081"), "details" : [ { "Name" : "Chris", "Age" : 21 }, { "Name" : "Carol", "Age" : 22 } ] }
