我的收藏中有以下文档
{
_id: ObjectId("5166fefbc482c31052000002"),
contact: [
{
home: 7735734105
},
{
office: 9583866301
}
],
user_name: "moti",
reportsTo: "bikram",
technology: [
{
name: ".net",
rating: 5
},
{
name: "JavaScript",
rating: 2
}
],
project: [
"Agile School",
"Draftmate"
],
type: "developer",
email: "motiranjan.pradhan@ajatus.co.in"
}和
{
_id: ObjectId("5166fe90c482c31052000001"),
contact: [
{
home: 7735734103
},
{
office: 9583866901
}
],
user_name: "ganesh",
reportsTo: "bikram",
technology: [
{
name: "JavaScript",
rating: 3
},
{
name: ".net",
rating: 4
}
],
project: [
"SLBC",
"Draftmate"
],
type: "developer",
email: "ganesh.patra@ajatus.co.in"
}
现在我需要找到只懂JavaScript的人的评分。目前如果我运行
db.users.find(
{
technology: {
$elemMatch: {
name: 'JavaScript'
}
}
},{user_name:1,'technology.name':1,_id:0}
).pretty()
我正在获取所有技术的名称(.net &JavaScript)及其相应的评级。我只需要用户名和他们各自的JavaScript评级。我需要使用聚合技术吗?
位置操作符'$'可用于将查询结果限制为第一个匹配元素。要在上面的查询中使用，您可以将其更改为:
db.users.find( { technology: { $elemMatch: { name: 'JavaScript' } } },{user_name:1,'technology.$.name':1,_id:0} )