Mongoose allows you to configure custom setters in which you do the comparison. pre(‘save’) by itself won’t give you what you need, but together:

schema.path('name').set(function (newVal) {var originalVal = this.name;if (someThing) {this._customState = true;} }); schema.pre('save', function (next) {if (this._customState) {...}next(); })

或者

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(); });

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