wendtry 此查询,返回查找为空
db.getCollection('tests').aggregate([
{$match: {typet:'Req'}},
{$project: {incharge:1}},
{$lookup:{
from: "users",
localField: "incharge", //this is the _id user from tests
foreignField: "_id", //this is the _id from users
as: "user"
}}
])
返回json
[
{
"_id": "57565d2e45bd27b012fc4db9",
"incharge": "549e0bb67371ecc804ad23ef",
"user": []
},
{
"_id": "57565d2045bd27b012fc4cbb",
"incharge": "549e0bb67371ecc804ad21ef",
"user": []
},
{
"_id": "57565d2245bd27b012fc4cc7",
"incharge": "549e0bb67371ecc804ad24ef",
"user": []
}
]
我试着写这篇文章,但什么也没发生
UPDATE
这是"用户"文档
{
"_id" : ObjectId("549e0bb67371ecc804ad24ef"),
"displayname" : "Jhon S."
},
{
"_id" : ObjectId("549e0bb67371ecc804ad21ef"),
"displayname" : "George F."
},
{
"_id" : ObjectId("549e0bb67371ecc804ad23ef"),
"displayname" : "Franc D."
}