mongodb - Does Mongoose provide access to previous value of property in pre('save')?

Question

I'd like to compare the new/incoming value of a property with the previous value of that property (what is currently saved in the db) within a pre('save') middleware.

Does Mongoose provide a facility for doing this?

Answer 1

The accepted answer works very nicely. An alternative syntax can also be used, with the setter inline with the Schema definition:

var Person = new mongoose.Schema({
  name: {
    type: String,
    set: function(name) {
      this._previousName = this.name;
      return name;
    }
});

Person.pre('save', function (next) {
  var previousName = this._previousName;
  if(someCondition) {
    ...
  }
  next();
});