用于规范化数据的Mongoose getter / setters [英] Mongoose getter / setters for normalizing data

问题描述

我有用户模式，它有一个用户名字段。我想这个字段是区分大小写的，所以用户可以注册一些名字，例如 BobDylan 。但是，我需要我的模式来验证新条目，以检查没有重复项，不敏感，例如 bobdylan 。

I have User schema which has a username field. I would like this field to be case sensitive, so that users may register names such as BobDylan. However, I need my schema to validate new entries to check there are no duplicates, incase sensitive, such as bobdylan.

我的研究告诉我，我应该在架构中创建一个额外的字段，用于存储小写/大写版本，以便我可以轻松地检查它是否是唯一的。我的问题是，如何使用Mongoose API实现这一点？

My research has taught me that I should create an additional field in the schema for storing a lower case / upper case version, so that I can easily check if it is unique. My question is, how would I achieve this with the Mongoose API?

我尝试使用集合函数，例如：

I have tried using a set function, such as:

UserSchema.path('username_lower_case').set(function(username_lower_case) {
  return this.username.toLowerCase()
});

但是，这个函数似乎没有运行。我基本上需要告诉 username_lower_case ，而不是用户名是，但小写。

However, this function doesn't seem to be running. I basically need to tell username_lower_case to be whatever username is, but in lower case.

推荐答案

一种方法是使用预先保存的钩子来实现。

One way would be to use a pre-save hook to do it.

UserSchema.pre('save', function (next) {
    this.username_lower_case = this.username && this.username.toLowerCase();
    next();
});

另一种方法是使 username a虚拟：

Another way would be to make username a virtual:

UserSchema.virtual('username').set(function (value) {
    this.username_raw = value;
    this.username_lower_case = value && value.toLowerCase();
}).get(function () {
    return this.username_raw;
});

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