Some time ago I was looking for a validation library/module for use in a small Express application that I was writing at the time. I couldn’t find anything that suited my taste so I decided to write one myself just for kicks. The goal was learning how to publish a module to npm and making a futile attempt to contribute something back to the vibrant Node.js community. node-validation is a minimal but slightly opinionated validation library for Node.js.
Installing node-validation can be done using the canonical package manager:
$ npm install node-validation
Validation rules must be defined in a custom validator by deriving from the base Validator.
After creating a validator object, an object that needs to be validated (the subject) can be passed to the validate method. The validate method returns an array of validation errors specifying a message and the name of the violating property.
var MyObjectValidator = function() {
Validator.call(this);
this.ruleFor('stringProperty').isNotEmpty();
this.ruleFor('otherStringProperty').hasMaximumLength(10);
this.ruleFor('numericStringProperty').isNumber()
.withMessage('Oops, something is wrong ...');
this.ruleFor('dateStringProperty')
.matches(/^(19|20)\d\d[-](0[1-9]|1[012])[-](0[1-9]|[12][0-9]|3[01])$/);
this.ruleFor('numberProperty').isInteger();
this.ruleFor('otherNumberProperty').isMaximum(5);
this.ruleFor('exoticProperty').is(function(value) {
return 3 === value.propertyA + value.propertyB;
}).withMessage('Either propertyA or propertyB has an incorrect value.');
};
util.inherits(MyObjectValidator, Validator);There you go. Head over to the GitHub repository and give it a try. I’m definitely looking forward to hear your feedback.
