比较猫鼬_id和字符串 [英] Comparing mongoose _id and strings

问题描述

我有一个node.js应用程序，它可以提取一些数据并将其粘贴到对象中，如下所示:

I have a node.js application that pulls some data and sticks it into an object, like this:

var results = new Object();

User.findOne(query, function(err, u) {
    results.userId = u._id;
}

当我基于存储的ID执行if/then时，比较永远不会成立:

When I do an if/then based on that stored ID, the comparison is never true:

if (results.userId == AnotherMongoDocument._id) {
    console.log('This is never true');
}

当我执行两个ID的console.log时，它们完全匹配:

When I do a console.log of the two id's, they match exactly:

User id: 4fc67871349bb7bf6a000002 AnotherMongoDocument id: 4fc67871349bb7bf6a000002

我假设这是某种数据类型问题，但是我不确定如何将result.userId转换为将导致上述比较为真的数据类型，而我的外包大脑(又名Google)无法帮助.

I am assuming this is some kind of datatype problem, but I'm not sure how to convert results.userId to a datatype that will result in the above comparison being true and my outsourced brain (aka Google) has been unable to help.

推荐答案

Mongoose使用mongodb-native驱动程序，该驱动程序使用自定义ObjectID类型.您可以将ObjectID与.equals()方法进行比较.在您的示例中，results.userId.equals(AnotherMongoDocument._id).如果您希望以JSON格式或Cookie来存储ObjectID的字符串化版本，则ObjectID类型也具有toString()方法.

Mongoose uses the mongodb-native driver, which uses the custom ObjectID type. You can compare ObjectIDs with the .equals() method. With your example, results.userId.equals(AnotherMongoDocument._id). The ObjectID type also has a toString() method, if you wish to store a stringified version of the ObjectID in JSON format, or a cookie.

如果使用ObjectID = require("mongodb").ObjectID(需要mongodb本地库)，则可以使用results.userId instanceof ObjectID检查results.userId是否是有效的标识符.

If you use ObjectID = require("mongodb").ObjectID (requires the mongodb-native library) you can check if results.userId is a valid identifier with results.userId instanceof ObjectID.

等等.

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