mongodb - 仅从 MongoDB 中选择一个字段

Question

这是我在 MongoDB 中的示例数据库

{"userName":"John Smith", "followers":8075,"body":"my text 1","confirmed":"no"}
{"userName":"James Bond", "followers":819, "body":"my text 2", "confirmed":"yes"}
{"userName":"Julia Roberts","followers":3882,"body":"my text 3","confirmed":"yes"}
{"userName":"Matt Damon","followers":6531, "body":"my text 4","confirmed":"yes"}
{"userName":"Amy Adams","followers":3941, "body":"my text 5","confirmed":"no"}

我需要选择拥有超过 3000 名关注者并确认帐户的用户名。这就是我想要做的:

db.collection.find( { $and:[{followers: { $gt: 3000 } },  {"confirmed" : "yes"}] })

但是这种方式给了我完整的匹配行，而我只需要用户名。能请教一下吗？

Answer 1

您必须指定返回字段；

db.collection.find( { $and:[{followers: { $gt: 3000 } }, {"confirmed": "yes"}] }, {userName: 1, _id: 0})

可以找到更多详细信息here

此外，如果您想抑制 _id 字段，您希望添加 _id: 0。其中的详细信息是here