egg-errors

Errors for Egg.js

egg-errors provide two kinds of errors that is Error and Exception.

Exception is system error that egg will log an error and throw exception, but it will be catched by onerror plugin.
Error is business error that egg will transform it to response.

Install

$ npm i egg-errors --save

Usage

Create an Error

const { EggError, EggException } = require('egg-errors');
let err = new EggError('egg error');
console.log(EggError.getType(err)); // ERROR

Create an Exception

err = new EggException('egg exception');
console.log(EggException.getType(err)); // EXCEPTION

You can import an error from an normal error object

err = new Error('normal error');
console.log(EggError.getType(err)); // BUILTIN
err = EggError.from(err);
console.log(EggError.getType(err)); // ERROR

Customize Error

Error can be extendable.

const { EggBaseError } = require('egg-errors');

class CustomError extends EggBaseError {
  constructor(message) {
    super({ message, code: 'CUSTOM_CODE' });
  }
 }

or using typescript you can customize ErrorOptions.

import { EggBaseError, ErrorOptions } from 'egg-errors';

class CustomErrorOptions extends ErrorOptions {
  public data: object;
}
class CustomError extends EggBaseError<CustomErrorOptions> {
  public data: object;
  protected options: CustomErrorOptions;

  constructor(options?: CustomErrorOptions) {
    super(options);
    this.data = this.options.data;
  }
}

Recommend use message instead of options in user land that it can be easily understood by developer, see http error.

HTTP Errors

HTTP Errors is BUILTIN errors that transform 400 ~ 500 status code to error objects. HttpError extends EggBaseError providing two properties which is status and headers;

const { ForbiddenError } = require('egg-errors');
const err = new ForbiddenError('your request is forbidden');
console.log(err.status); // 403

Support short name too:

const { E403 } = require('egg-errors');
const err = new E403('your request is forbidden');
console.log(err.status); // 403

FrameworkBaseError

FrameworkBaseError is for egg framework/plugin developer to throw framework error.it can format by FrameworkErrorFormater

FrameworkBaseError extends EggBaseError providing three properties which is module、serialNumber and errorContext

FrameworkBaseError could not be used directly, framework/plugin should extends like this

const { FrameworkBaseError } = require('egg-errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const err = new EggMysqlError('error message', '01', { traceId: 'xxx' });
console.log(err.module); // EGG_MYSQL
console.log(err.serialNumber); // 01
console.log(err.code); // EGG_MYSQL_01
console.log(err.errorContext); // { traceId: 'xxx' }

create frameworkError with formater

use the static method .create(message: string, serialNumber: string | number, errorContext?: any) to new a frameworkError and format it convenient

const { FrameworkBaseError } = require('egg-errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const err = EggMysqlError.create('error message', '01', { traceId: 'xxx' });
console.log(err.message); 
// =>
framework.EggMysqlError: error message [ https://eggjs.org/zh-cn/faq/EGG_MYSQL/01 ]

FrameworkErrorFormater

FrameworkErrorFormater will append a faq guide url in error message.this would be helpful when developer encountered a framework error

the faq guide url format: ${faqPrefix}/${err.module}/${err.serialNumber}, faqPrefix is https://eggjs.org/zh-cn/faq by default. can be extendable or set process.env.EGG_FRAMEWORK_ERR_FAQ_PERFIX to override it.

const { FrameworkErrorFormater } = require('egg-errors');

class CustomErrorFormatter extends FrameworkErrorFormater {
  static faqPrefix = 'http://www.custom.com/faq';
}

.format(err)

format error to message, it will not effect origin error

const { FrameworkBaseError, FrameworkErrorFormater } = require('egg-errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const message = FrameworkErrorFormater.format(new EggMysqlError('error message', '01'));
console.log(message); 
// => message format like this
framework.EggMysqlError: error message [ https://eggjs.org/zh-cn/faq/EGG_MYSQL/01 ]
...stack
...
code: "EGG_MYSQL_01"
serialNumber: "01"
errorContext:
pid: 66568
hostname: xxx


// extends
class CustomErrorFormatter extends FrameworkErrorFormater {
  static faqPrefix = 'http://www.custom.com/faq';
}
const message = CustomErrorFormatter.format(new EggMysqlError('error message', '01'));
console.log(message); 
// =>
framework.EggMysqlError: error message [ http://www.custom.com/faq/EGG_MYSQL/01 ]
...

.formatError(err)

append faq guide url to err.message

const { FrameworkBaseError, FrameworkErrorFormater } = require('egg-errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const err = FrameworkErrorFormater.formatError(new EggMysqlError('error message', '01'));
console.log(err.message); // error message [ https://eggjs.org/zh-cn/faq/EGG_MYSQL/01 ]

Available Errors

BaseError
|- EggBaseError
|  |- EggError
|  |- HttpError
|  |  |- NotFoundError, alias to E404
|  |  `- ...
|  |- FrameworkBaseError
|  `- CustomError
`- EggBaseException
   |- EggException
   `- CustomException