Mongoose getter / setters for normalizing data

Question

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

Answer 1

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();
});

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;
});