http-problem-details-mapper

0.1.7 verified Sat Apr 25 auth: no javascript

A library for mapping errors to RFC 7807 HTTP Problem Details (ProblemDocument) objects. Version 0.1.7 ships TypeScript types and follows Conventional Commits. It provides an extensible mapper pattern (ErrorMapper, MapperRegistry, MappingStrategy) to convert domain errors into structured HTTP error responses. Key differentiators: integrates with http-problem-details and express-http-problem-details for a complete REST error handling stack. Release cadence is low; version 0.1.x is stable and maintained. Peer dependency on http-problem-details (^0.1.0) required.

Common errors

error Error: Could not map error ↓

cause No mapper registered for the error type and useDefaultErrorMapper set to false.

fix

error TypeError: errorMapper is not a constructor ↓

cause Passed an instance instead of a class to ErrorMapper constructor.

fix

Use super(NotFoundError) not super(new NotFoundError()).

error Cannot find module 'http-problem-details' ↓

cause Missing peer dependency.

fix

npm install http-problem-details.

Warnings

gotcha ErrorMapper constructor takes an Error class (constructor function), not an instance. Passing an instance will break type checks and runtime mapping. ↓

fix Ensure the argument to super is the Error class itself, e.g., super(NotFoundError).

deprecated IErrorMapper interface is deprecated. Use ErrorMapper base class instead. ↓

fix Extend ErrorMapper class rather than implementing IErrorMapper.

gotcha MapperRegistry.getMapper throws if no mapper found when useDefaultErrorMapper is false. Default is true and returns DefaultErrorMapper. ↓

fix Either enable default mapper or always check mapper existence before calling mapError.

Install

npm install http-problem-details-mapper

yarn add http-problem-details-mapper

pnpm add http-problem-details-mapper

Imports

ErrorMapper

wrong

const ErrorMapper = require('http-problem-details-mapper').ErrorMapper

correct

import { ErrorMapper } from 'http-problem-details-mapper'

ESM supported; use named export. CommonJS require works but use destructuring.

MapperRegistry

wrong

import MapperRegistry from 'http-problem-details-mapper'

correct

import { MapperRegistry } from 'http-problem-details-mapper'

MapperRegistry is a named export, not default.

DefaultErrorMapper

wrong

const { defaultErrorMapper } = require('http-problem-details-mapper')

correct

import { DefaultErrorMapper } from 'http-problem-details-mapper'

Class name is PascalCase; common camelCase mistake.

Quickstart

Shows full setup: custom error, mapper, registration, and mapping with ProblemDocument.

import { ErrorMapper, MapperRegistry } from 'http-problem-details-mapper';
import { ProblemDocument } from 'http-problem-details';

class NotFoundError extends Error {
  constructor(options) {
    super();
    this.message = `${options.type} with id ${options.id} not found`;
  }
}

class NotFoundErrorMapper extends ErrorMapper {
  constructor() {
    super(NotFoundError);
  }
  mapError(error) {
    return new ProblemDocument({ status: 404, title: error.message, type: 'http://tempuri.org/NotFoundError' });
  }
}

class MyMappingStrategy {
  constructor(registry) { this.registry = registry; }
  map(error) {
    const mapper = this.registry.getMapper(error);
    if (mapper) return mapper.mapError(error);
    throw new Error('Could not map error');
  }
}

const registry = new MapperRegistry().registerMapper(new NotFoundErrorMapper());
const strategy = new MyMappingStrategy(registry);
const error = new NotFoundError({ type: 'customer', id: '123' });
const problem = strategy.map(error);
console.log(problem);