Skmatc (schematic)

Automatic Schematic Validation for JavaScript Objects

Skmatc provides an extremely powerful, extensible schema validation tool which we developed for Iridium. It gives you the ability to flexibly validate JavaScript objects against a schema to ensure data integrity and add structure to otherwise unstructured data.

Example

var skmatc = require('skmatc');

var schema = new skmatc({
	id: String,
	username: /\w[\w\d_]{7,}/,
	email: { $type: /.+@.+\..+/, $message: 'The email address you entered was invalid, please check it and try again.' },
	website: { $required: false, $type: String },
	sessions: [String],
	friends: {
		$propertyType: {
			addedOn: Date
		}
	}
});

var obj = {
	id: 'aaaaaaaaaa',
	username: 'spartan563',
	email: 'admin@sierrasoftworks.com',
	sessions: [],
	friends: {
		bob: { addedOn: new Date(123456789) }
	}
};

var result = schema.validate(obj);
if(result.failed) throw result.error;

Features

Skmatc provides a number of powerful features which allow you to validate almost any type of data structure, and if none of the included validators suit your needs you can easily add your own.

• Easy To Use Easily define schemas using standard JavaScript objects to describe the structure in a readable manner.
• Flexible Implement custom validator plugins for complex validation scenarios while making use of Skmatc's other cool features.

Built In Validators

Skmatc comes with a number of built in validators which are generally sufficient to address any common usage scenario. If you find yourself needing some more complex validation logic then you can easily implement your own custom validator using Skmatc's simple API.

Command Codes Preprocessor

The command codes preprocessor implements the command codes logic which dictates how certain special case objects are treated. Command code nodes consist of properties which are exclusively prefixed with $ and contain either a $type or $propertyType property.

schema = {
	optionalRx: {
		$required: false,
		$type: /\w+/
	},
	anonProperties: {
		$message: 'anonProperties should only be Boolean values',
		$propertyType: Boolean
	}
};

matches = {
	optionalRx: undefined,
	anonProperties: {
		one: true,
		two: false
	}
};

Basic Validator

The basic validator expects schema values of either true or false - dictating whether a value is required to be present (not-null and defined) or not (may be null or undefined).

schema = true;
matches = 'anything';

schema = false;
matches = 'anything' || null || undefined;

Object Validator

The object validator provides recursive object property validation using any combination of the other validators to do value validation. Values which do not appear in the schema are ignored, take a look at the Command Codes section for more information on validating anonymous properties.

schema = {
	name: String,
	age: Number,
	parents: {
		dad: String,
		mom: String
	}
};

matches = {
	name: 'Ben',
	age: 21,
	parents: {
		dad: 'Bob',
		mom: 'Jane'
	}
};

Array Validator

The array validator allows you to validate array elements, as well as allowing you to validate array sizes. Array elements are all validated using a combination of the other validators.

schema = [String];
matches = ['a', 'b', 'c'];

schema = [String, minElements];
matches = ['a', 'b', ...];

schema = [String, minElements, maxElements];
matches = ['a', 'b', ...];

Type Validator

The type validator allows you to validate some basic JavaScript types like String, Number, Date, Boolean, Object and Function. For more complex types we suggest implementing a custom validator.

schema = String;
matches = 'some string';

schema = Number;
matches = 10.00;

schema = Date;
matches = new Date();

schema = Boolean;
matches = true;

schema = Object;
matches = {};

schema = Function;
matches = function() { };

RegExp Validator

The RegExp validator allows you to validate strings using regular expression matching and comes in handy in many situations where structured text is required.

schema = /\w[\w\d_]{7,}/;
matches = 'spartan563';

Custom Validators

Custom validators are created by subclassing the skmatc.Validator to implement your own handles and validate methods. To make your life a little easier, we've included the skmatc.create function which handles the subclassing for you.

You can load validators into a specific skmatc instance, or present a validator module to skmatc for global inclusion in all future instances. Validator modules are expected to be composed of a function which recieves a skmatc instance as its only argument and returns a skmatc.Validator.

Validator Modules

Validator modules are loaded automatically by all future skmatc instances upon initialization and can be created by using the skmatc.create(handles, validate) function.

var skmatc = require('skmatc');

skmatc.register(skmatc.create(function(schema) {
	// Decide whether this validator can handle the schema type
	return schema == 'custom';
}, function(schema, data, path) {
	return this.assert(data == 'valid', 'My custom error message (optional)');
}));

Validators

If you wish to load a validator into a specific skmatc instance then you will need link the validator to skmatc manually - this can be done using the skmatc.create(handles, validate) function.

var skmatc = require('skmatc');
var schema = new skmatc({ });
schema.register(skmatc.create(schema, function(schema) {
	// Decide whether this validator can handle the schema type
	return schema == 'custom';
}, function(schema, data, path) {
	return this.assert(data == 'valid', 'My custom error message (optional)');
}));