NError

Nested Error ES6 class

Installation

npm install --save nerror

Usage

An abstract example

const NError = require('nerror');

try {
    try {
        try {
            let error = new Error('Some DB error');
            error.code = 42000;
            throw error;
        } catch (error) {
            throw new NError(error, { sqlState: error.code }, 'Could not insert row');
        }
    } catch (error) {
        throw new NError(error, { customerId: 9000 }, 'Could not create user');
    }
} catch (error) {
    console.log(error.messages, JSON.stringify(error.info, undefined, 4));
    /* Could not create user: Could not insert row: Some DB error {
           "sqlState": 42000,
           "customerId": 9000
       } */

    console.log(error.fullStack);
    /* NError: Could not create user
           at Object.<anonymous> (/home/ross/tmp/nerror/test.js:13:15)
           at Module._compile (module.js:570:32)
           at Object.Module._extensions..js (module.js:579:10)
           at Module.load (module.js:487:32)
           at tryModuleLoad (module.js:446:12)
           at Function.Module._load (module.js:438:3)
           at Module.runMain (module.js:604:10)
           at run (bootstrap_node.js:393:7)
           at startup (bootstrap_node.js:150:9)
           at bootstrap_node.js:508:3
       NError: Could not insert row
           at Object.<anonymous> (/home/ross/tmp/nerror/test.js:10:19)
           at Module._compile (module.js:570:32)
           at Object.Module._extensions..js (module.js:579:10)
           at Module.load (module.js:487:32)
           at tryModuleLoad (module.js:446:12)
           at Function.Module._load (module.js:438:3)
           at Module.runMain (module.js:604:10)
           at run (bootstrap_node.js:393:7)
           at startup (bootstrap_node.js:150:9)
           at bootstrap_node.js:508:3
       Error: Some DB error
           at Object.<anonymous> (/home/ross/tmp/nerror/test.js:6:25)
           at Module._compile (module.js:570:32)
           at Object.Module._extensions..js (module.js:579:10)
           at Module.load (module.js:487:32)
           at tryModuleLoad (module.js:446:12)
           at Function.Module._load (module.js:438:3)
           at Module.runMain (module.js:604:10)
           at run (bootstrap_node.js:393:7)
           at startup (bootstrap_node.js:150:9)
           at bootstrap_node.js:508:3 */
}

NError

new NError([parent,] [info,] ...args)

parent is optional parent error instance

info is optional information attached to the error. it will be merged with parents' info objects

...args - rest is usual Error constructor arguments

Examples

The following are all valid constructor calls:

• new NError('Error occurred') // just like usual Error

• new NError(new Error('Test'), 'Error occurred') // pass the parent

• new NError({ someKey: "some value" }, 'Error occurred') // pass info

• new NError(new NError('Some error'), { key: 'value' }, 'Error occurred') // do both

.parent

Parent error accessor

.info

Combined information created by merging infos of all the parent chain

.messages

Combined messages of all the parents

.fullStack

Combined stack info of all the parents

.toArray()

Convert this error chain to an array. Consider the following example:

let err1 = new Error('1');
let err2 = new NError(err1, '2');
let err3 = new NError(err2, '3');

err3.toArray() will return: [ err3, err2, err1 ]