http.exception.ts

import { isObject, isString } from '../utils/shared.utils';

export type HttpExceptionOptions = {
  cause?: Error;
};

/**
 * Defines the base Nest HTTP exception, which is handled by the default
 * Exceptions Handler.
 *
 * @see [Built-in HTTP exceptions](https://docs.nestjs.com/exception-filters#built-in-http-exceptions)
 *
 * @publicApi
 */
export class HttpException extends Error {
  /**
   * Instantiate a plain HTTP Exception.
   *
   * @example
   * throw new HttpException()
   * throw new HttpException('message', HttpStatus.BAD_REQUEST)
   * throw new HttpException({ reason: 'this can be a human readable reason' }, HttpStatus.BAD_REQUEST)
   * throw new HttpException(new Error('Cause Error'), HttpStatus.BAD_REQUEST)
   * throw new HttpException('custom message', HttpStatus.BAD_REQUEST, {
   *  cause: new Error('Cause Error'),
   * })
   *
   *
   * @usageNotes
   * The constructor arguments define the response and the HTTP response status code.
   * - The `response` argument (required) defines the JSON response body. alternatively, it can also be
   *  an error object that is used to define an error [cause](https://nodejs.org/en/blog/release/v16.9.0/#error-cause).
   * - The `status` argument (required) defines the HTTP Status Code.
   * - The `options` argument (optional) defines additional error options. Currently, it supports the `cause` attribute,
   *  and can be used as an alternative way to specify the error cause: `const error = new HttpException('description', 400, { cause: new Error() });`
   *
   * By default, the JSON response body contains two properties:
   * - `statusCode`: the Http Status Code.
   * - `message`: a short description of the HTTP error by default; override this
   * by supplying a string in the `response` parameter.
   *
   * To override the entire JSON response body, pass an object to the `createBody`
   * method. Nest will serialize the object and return it as the JSON response body.
   *
   * The `status` argument is required, and should be a valid HTTP status code.
   * Best practice is to use the `HttpStatus` enum imported from `nestjs/common`.
   *
   * @param response string, object describing the error condition or the error cause.
   * @param status HTTP response status code.
   * @param options An object used to add an error cause.
   */
  constructor(
    private readonly response: string | Record<string, any>,
    private readonly status: number,
    private readonly options?: HttpExceptionOptions,
  ) {
    super();
    this.initMessage();
    this.initName();
    this.initCause();
  }

  public cause: Error | undefined;

  /**
   * Configures error chaining support
   *
   * See:
   * - https://nodejs.org/en/blog/release/v16.9.0/#error-cause
   * - https://github.com/microsoft/TypeScript/issues/45167
   */
  public initCause(): void {
    if (this.options?.cause) {
      this.cause = this.options.cause;
      return;
    }

    if (this.response instanceof Error) {
      this.cause = this.response;
    }
  }

  public initMessage() {
    if (isString(this.response)) {
      this.message = this.response;
    } else if (
      isObject(this.response) &&
      isString((this.response as Record<string, any>).message)
    ) {
      this.message = (this.response as Record<string, any>).message;
    } else if (this.constructor) {
      this.message = this.constructor.name
        .match(/[A-Z][a-z]+|[0-9]+/g)
        .join(' ');
    }
  }

  public initName(): void {
    this.name = this.constructor.name;
  }

  public getResponse(): string | object {
    return this.response;
  }

  public getStatus(): number {
    return this.status;
  }

  public static createBody(
    objectOrError: object | string,
    description?: string,
    statusCode?: number,
  ) {
    if (!objectOrError) {
      return { statusCode, message: description };
    }
    return isObject(objectOrError) && !Array.isArray(objectOrError)
      ? objectOrError
      : { statusCode, message: objectOrError, error: description };
  }
}