howhap list

npm install --save howhap-list

Stores a list of howhap errors for easy manipulation and display.

Usage

let HowhapList = require('howhap-list');
 
let list = new HowhapList({
    default: {
        message: 'An unknown error occurred',
        status: 500
    },
    email: {
        message: '{{email}} is an invalid email address',
        status: 400,
        params: {
            email: 'foo'
        }
    }
});

Constructor

let list = new HowhapList(errors, options);

Both errors and options are optional. Errors can be a plain vanilla javascript object that represents the list of keyed errors.

Methods

HowhapList.add(messageAndStatus, params, key)

Adds a new error to the list. The key defaults to 'default'. Below are some examples...

messageStatus can be an object

list.add({
    message: '{{email}} is an invalid email address',
    status: 400
}, {email: 'foo'}, 'email');
 
// RESULT:
/*
{
    email: {
        message: '{{email}} is an invalid email address',
        status: 400,
        params: {
            email: 'foo'
        }
    }
}
*/

messageStatus can be a string if the availableErrors option is supplied

list.add('AUTH.INVALID_EMAIL', {params: email: 'foo'}, 'email');
 
// RESULT:
/*
{
    email: {
        message: '{{email}} is an invalid email address',
        status: 400,
        params: {
            email: 'foo'
        }
    }
}
*/

neither params nor key are required

list.add('AUTH.INVALID_EMAIL');
 
// RESULT:
/*
{
    email: {
        message: '{{email}} is an invalid email address',
        status: 400
    }
}
*/

params can be supplied with out a key. The key will default to 'default'

list.add('AUTH.INVALID_EMAIL', {email: 'foo'});
 
// RESULT:
/*
{
    default: {
        message: '{{email}} is an invalid email address',
        status: 400,
        params: {
            email: 'foo'
        }
    }
}
*/

key can be supplied with out a params. The params will default to an empty object

list.add('AUTH.INVALID_EMAIL', 'email');
 
// RESULT:
/*
{
    email: {
        message: '{{email}} is an invalid email address',
        status: 400,
        params:{}
    }
}
*/

HowhapList.remove(key)

Removes an error by its key.

list.remove('default');

HowhapList.toJSON()

Returns a JSON representation of the howhap list with error objects rendered to strings.

let plainObject = list.toJSON();

HowhapList.toObject()

Returns a JSON representation of the howhap list with error objects preserved.

let plainObject = list.toObject();

HowhapList.display(key)

Displays a specific error based on its (optional) key

let list = new HowhapList({
    default: {
        message: 'An unknown error occurred',
        status: 500
    },
    email: {
        message: '{{email}} is an invalid email address',
        status: 400,
        params: {
            email: 'foo'
        }
    }
});
 
list.display(); // 'An unknown error occurred
list.display('default'); // 'An unknown error occurred
list.display('email'); // foo is an invalid email address

Options

options.availableErrors

availableErrors can hold an objet of errors that can be easily added to the list. For example:

// Errors are defined once in the options argument
let list = new HowhapList(null, {
    availableErrors: {
    	API: {
        	UNKNOWN: {
            	message: 'An unknown error occurred.',
                status: 500
            },
        	NOT_FOUND: {
            	message: 'The model with id {{id}} was not found.',
                status: 404
            },
            PERMISSION_DENIED: {
            	message: 'You don\'t have permission to {{action}} the resource {{resource}}',
                status: 401
            }
        },
        EMAIL: {
        	UNREACHABLE: {
            	message: 'The email address {{email}} is unreachable.',
                status: 400
            }
        }
    }
});
 
// Errors can be easily added via a string
 
list.add('API.UNKNOWN');
list.add('API.NOT_FOUND', {id: 7});
list.add('EMAIL.UNREACHABLE', {email: '[e-mail]'});

options.logger

logger is an object that will be called each time an error is added. Works natively with bunyan but you can also add your own logger. It should adhere to the following interface (for example):

let logger = {
    debug: function(message, status, params) {
    	console.log('DEBUG:', message, status, params);
    },
    warn: function(message, status, params) {
    	console.log('WARN:', message, status, params);
    },
    error: function(message, status, params) {
    	console.log('ERROR:', message, status, params);
    }
};

Here's an example of how to configure your logger.

let bunyan = require('bunyan');
let HowhapList = require('howhap-list');
 
let list = new HowhapList(null, {
    logger: bunyan.createLogger({name: "myapp"})
});