node.js - mongoose custom validation using 2 fields

Question

I want to use mongoose custom validation to validate if endDate is greater than startDate. How can I access startDate value? When using this.startDate, it doesn't work; I get undefined.

var a = new Schema({
  startDate: Date,
  endDate: Date
});

var A = mongoose.model('A', a);

A.schema.path('endDate').validate(function (value) {
  return diff(this.startDate, value) >= 0;
}, 'End Date must be greater than Start Date');

diff is a function that compares two dates.

Answer 1

You can do that using Mongoose 'validate' middleware so that you have access to all fields:

ASchema.pre('validate', function(next) {
    if (this.startDate > this.endDate) {
        next(new Error('End Date must be greater than Start Date'));
    } else {
        next();
    }
});

Note that you must wrap your validation error message in a JavaScript Error object when calling next to report a validation failure.