猫鼬中的 id 和 _id 有什么区别? [英] What is the difference between id and _id in mongoose?

问题描述

mongoose 中的 _id 和 id 有什么区别?哪个更适合参考?

What is the difference between _id and id in mongoose? Which is better for referencing?

推荐答案

来自 文档:

默认情况下，Mongoose 为您的每个架构分配一个 id 虚拟 getter它返回文档 _id 字段转换为字符串，或者在这种情况下ObjectIds，它的十六进制字符串.

Mongoose assigns each of your schemas an id virtual getter by default which returns the documents _id field cast to a string, or in the case of ObjectIds, its hexString.

所以，基本上，id getter 返回文档 _id 的字符串表示(默认情况下，它被添加到所有 MongoDB 文档中，并且默认类型为 ObjectId).

So, basically, the id getter returns a string representation of the document's _id (which is added to all MongoDB documents by default and have a default type of ObjectId).

关于什么更适合引用，这完全取决于上下文(即，您想要 ObjectId 还是 string).例如，如果比较 id 的字符串可能更好，因为 ObjectId 不会通过相等测试，除非它们是相同的实例(无论是什么它们代表的价值).

Regarding what's better for referencing, that depends entirely on the context (i.e., do you want an ObjectId or a string). For example, if comparing id's, the string is probably better, as ObjectId's won't pass an equality test unless they are the same instance (regardless of what value they represent).

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