我试图在 findOne() 上使用投影参数从文档(统计信息)中提取单个字段,但它似乎只是返回整个文档。我在 Node.js 中使用版本“mongodb”:“^3.4.1”
这是文档结构
{ _id: 5e563015fa9a1a0134cac3cb,
username: 'user1',
password: '1234',
email: '[email protected] /cdn-cgi/l/email-protection',
stats:
{ totalViewed: 122,
totalUnique: 4,
tknow: 80,
tdknow: 42,
setCnt: 78 },
progress:
[ { cardId: 1001, knowCnt: 3, dknowCnt: 4 },
{ cardId: 1016, knowCnt: 0, dknowCnt: 0 } ] }
这是代码:
var findOneDoc = function() {
db.collection("testusers").findOne(
{ username: "user1" },
{ stats: 1 }, //field to return
function(err, result) {
if (err) {
console.log("Error: ", err);
}
console.log("Success: ", result);
}
);
};
findOneDoc();
我也尝试过:{$project: {stats: 1}}
,无济于事
Thanks