@osskit/fastify-error-handler

@osskit/fastify-error-handler is a reusable error handler for Fastify. It helps you manage error responses in a consistent and customizable manner, with built-in support for logging and filtering allowed error properties.

Features

• Handles various error types and provides appropriate HTTP status codes.
• Logs errors with customizable logging function.
• Allows specifying which properties of the error object should be included in the response.
• Works seamlessly with Fastify's error handling mechanism.

Installation

Install the package via npm:

npm install @osskit/fastify-error-handler

Or via yarn:

yarn add @osskit/fastify-error-handler

Usage

Basic Usage

import fastify from 'fastify';
import { fastifyErrorHandler } from '@osskit/fastify-error-handler';

const server = fastify();

server.setErrorHandler(fastifyErrorHandler());

server.get('/', async () => {
  // Simulate an error
  throw new Error('Test error');
});

server.listen(3000, (err, address) => {
  if (err) {
    console.error(err);
    process.exit(1);
  }
  console.log(`Server listening at ${address}`);
});

Custom Logging and Allowed Properties

You can customize the error handler by providing a logging function and specifying which properties of the error object should be included in the response.

import fastify from 'fastify';
import { fastifyErrorHandler } from '@osskit/fastify-error-handler';

const server = fastify();

const customLogger = ({ error, request, reply }) => {
  console.log('Custom log:', error);
};

const options = {
  log: customLogger,
  allowedProperties: ['detail', 'type']
};

server.setErrorHandler(fastifyErrorHandler(options));

server.get('/', async () => {
  const error = new Error('Test error');
  error.detail = 'Detailed error information';
  error.type = 'CustomError';
  throw error;
});

server.listen(3000, (err, address) => {
  if (err) {
    console.error(err);
    process.exit(1);
  }
  console.log(`Server listening at ${address}`);
});

Handling HTTP Errors

The error handler works well with HTTP errors created using libraries like http-errors.

import fastify from 'fastify';
import createHttpError from 'http-errors';
import { fastifyErrorHandler } from '@osskit/fastify-error-handler';

const server = fastify();

server.setErrorHandler(fastifyErrorHandler());

server.get('/not-found', async () => {
  throw createHttpError(404, 'Resource not found');
});

server.listen(3000, (err, address) => {
  if (err) {
    console.error(err);
    process.exit(1);
  }
  console.log(`Server listening at ${address}`);
});

API

fastifyErrorHandler(options?)

Returns a Fastify error handler function.

options

• log (optional): A function to log errors. Receives an object with error, request, and reply properties.
• allowedProperties (optional): An iterable of property names that are allowed to be included in the error response.

License

This package is licensed under the MIT License. See the LICENSE file for more details.