techjacker/custom-errors

Custom Javascript Error Classes optimised for error logging

Custom Error Classes

• All classes inherit from the abstract class (lib/abstract-error.js) inspired by dustin senos's post.
• The abstract error class inherits from the in built error object.
• All error classes exported in lib/main.js -> index.js
• Easy logging integration with express.js using the log errors module

App Error Classes (module.exports.general)

1. ValidationError
2. DatabaseError

Express Error Classes (module.exports.request)

1. BadRequest = Bad Request Error (400)
2. Unauthorized = Unauthorized Error (401)
3. Forbidden = Forbidden Error (403)
4. NotAcceptable Request Not Acceptable Error (406)

Sample Usage

1. General Error Classes

var main 			= require('./../lib/main');
var ValidationError = main.general.ValidationError;

var msg 	 = "terrible input",
	ValError = new ValidationError(msg);

console.log('ValError', ValError);

STDOUT output:

ValError {
	name: 'Validation',
	logLevel: 'warning',
	doNotKill: undefined,
	resCode: undefined,
	message: 'not a valid date'
}

2. Request Error Classes

var BadRequestError = main.request.BadRequest;
var msg = "just an awful request",
	ReqError = new BadRequestError(msg);

console.log('ReqError', ReqError);

STDOUT output:

ReqError {
	name: 'BadRequest',
	logLevel: 'warning',
	resCode: 400,
	message: 'just an awful request'
}

Using with Express.js

Easy integration with the log errors module

var BadRequestError = require('customErrors').request.BadRequest;
var logErrors   = require('log-errors');

// define some routes
app.get('/some/route', function(req, res, next) {
	if ('error thrown') {
		next(new BadRequestError('reason for the bad request being thrown'));
	}
});

//... catchall error middleware (put at very end beneath all routes)
app.configure('development', function() {

	// wrap the logger if you need to do something
	// with the error before passing it to the logger
    app.use(function(err, req, res, next) {
		err.resCode || (err.resCode = 400);
        logErrors.development(err, req, res, next);
    });
});

app.configure('production', function() {
	// defaults to sending 500 response if err.resCode is not set
    app.use(logErrors.production);
});

Reference

Header status codes

log levels

Visionmedia Logging Module

0 EMERGENCY system is unusable
1 ALERT action must be taken immediately
2 CRITICAL the system is in critical condition
3 ERROR error condition
4 WARNING warning condition
5 NOTICE a normal but significant condition
6 INFO a purely informational message
7 DEBUG messages to debug an application