Error format implementation of the RFC 7807 for NodeJS HTTP environments

useAPIError.ts

import type { CompatibilityEvent } from 'h3'
import HttpStatusCode from '~~/const/httpStatusCode'
import { APIErrorTitle } from './apiErrorTitle'

/** Format of the [RFC 7807](https://www.rfc-editor.org/rfc/rfc7807) */
export type useAPIErrorOptions<T> = T & {
  /** A URI that identifies the problem type.
   * This specification encourages that, when dereferenced,
   * it provide human-readable documentation for the problem type
  */
  type?: string

  /**
   * Human-readable summary of the problem 
   */
  title?: APIErrorTitle

  /**
   * Redondant HTTP code with the one in header
   */
  status: HttpStatusCode

  /**
   * A human-readable explanation specific to error. Ought to focus on helping the client correct the problem.
   */
  detail?: string

  /**
   * a URI reference that identifies the specific occurrence of the problem.
   * Default to the current route called
   */
  instance?: string
}

/**
 * Standard way to send an error to the client.
 * 
 * @param event the object provided by an eventHandler of H3
 * @param options fields of the [RFC 7807](https://www.rfc-editor.org/rfc/rfc7807)
 * @returns the modified event. Ready to be returned as response.
 */
export const useAPIError = <T>(event: CompatibilityEvent, options: useAPIErrorOptions<T>) => {
  const { res } = event

  // Modify the request status code in-place
  res.statusCode = options.status
  // Set the expected header
  res.setHeader('Content-Type', 'application/problem+json')

  if (!options.instance) {
    options.instance = event.req.url
  }

  return options
}