猫鼬选择字段(嵌套) [英] Mongoose select fields (nested)

问题描述

我试图在猫鼬中使用select运算符为以下对象选择某些字段:

I am trying to use the select operator in mongoose to select certain fields for the following object:

{
    "_id" : ObjectId("5249bb97a5de48bda3000003"),
    "id": 1,
    "geometry" : {
        "coordinates" : [
            1,
            1
        ],
        "type" : "Point"
    },
    "properties" : {
        "TYPE" : "Some Type",
            "TIMESTAMP": ......
    },
    "type" : "Feature"
}

我想mongo仅返回'properties.TYPE'和properties.TIMESTAMP字段.我可以在mongo中执行以下查询:

I would like to mongo to return only the 'properties.TYPE' and properties.TIMESTAMP fields. I can do this in mongo with the following query:

db.features.find({id: 1}, {'properties.TYPE': 1, 'properties.TIMESTAMP': 1})

我试图在猫鼬中使用select语句来做同样的事情: var字段= { 属性:{OBJECTID:1，TIMESTAMP:1} } var query = Feature.find({id:1}).select(fields);

I am trying to use the select statement in mongoose to do the same thing: var fields = { properties: { OBJECTID: 1, TIMESTAMP: 1 } } var query = Feature.find({id: 1}).select(fields);

Mongo尝试执行此操作时会引发错误，因此我不确定猫鼬是否正确设置了嵌套字段对象的格式.

Mongo throws an error when trying to do that so I am not sure mongoose is formatting a nested fields object correctly.

这是执行此操作的正确方法吗?

Is this the proper way to do this?

推荐答案

您可以在select对象中的Mongoose中使用与find示例相同的点符号样式:

You can use the same dot notation style in the select object with Mongoose as you do in your find example:

var fields = { 'properties.OBJECTID': 1, 'properties.TIMESTAMP': 1 };
var query = Feature.find({id: 1}).select(fields);

您还可以使用猫鼬样式选择字符串:

You can also use a Mongoose style selection string:

var query = Feature.find({id: 1})
    .select('properties.OBJECTID properties.TIMESTAMP');

这篇关于猫鼬选择字段(嵌套)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！