Mongo查询以从集合中获取选择性字段

Question

是否可以从mongo集合中提取选择性字段。

假设我的收藏是

USer_info
{"_id" : ObjectId("56e0a3a2d59feaa43fba49d5", "date":"2018-07-23T00:00:00.000Z", "Name":"ABC", "ID": "1234", "Subjects":"[Maths, Physics, Science, Music]"}
{"_id" : ObjectId("56e0a3a2d5hjhfjtaese45d5", "date":"2018-07-23T00:00:00.000Z", "Name":"BCS", "ID": "3456", "Subjects":"[CS, Physics, Business]"}
{"_id" : ObjectId("56e0a3a2d59feaa43fba49d6", "date":"2018-07-23T00:00:00.000Z", "Name":"XYZ", "ID": "786", "Subjects": "[Agricultar, Business, Music]"}

查询仅列出名称和SUbjects字段：

{"Name":"ABC", "Subjects":"[Maths, Physics, Science, Music]"}
{"Name":"BCS", "Subjects":"[CS, Physics, Business]"}
{"Name":"XYZ", "Subjects": "[Agricultar, Business, Music]"}

不确定这是否是重复的，但我没有得到任何类似的东西，所以张贴它。

Answer 1

您必须定义.find()方法的投影部分，以指定应返回哪些字段。您还必须明确排除_id，请尝试：

col.find({}, { "_id": 0, "Name": 1, "Subjects": 1 })