Exception handling

Exceptions raised during an HTTP request are handled by the HttpExceptionHandler defined inside the ./app/exceptions/handler.ts file. Inside this file, you can decide how to convert exceptions to responses and log them using the logger or report them to an external logging provider.

The HttpExceptionHandler extends the ExceptionHandler class, which does all the heavy lifting of handling errors and provides you with high-level APIs to tweak the reporting and rendering behavior.

import app from '@adonisjs/core/services/app'
import { HttpContext, ExceptionHandler } from '@adonisjs/core/http'

export default class HttpExceptionHandler extends ExceptionHandler {
  protected debug = !app.inProduction
  protected renderStatusPages = app.inProduction

  async handle(error: unknown, ctx: HttpContext) {
    return super.handle(error, ctx)
  }

  async report(error: unknown, ctx: HttpContext) {
    return super.report(error, ctx)
  }
}

Assigning error handler to the server

The error handler is registered with the AdonisJS HTTP server inside the start/kernel.ts file. We lazily import the HTTP handler using the #exceptions alias defined in the package.json file.

server.errorHandler(() => import('#exceptions/handler'))

Handling exceptions

The exceptions are handled by the handle method on the exceptions handler class. By default, the following steps are performed while handling an error.

Check if the error instance has a handle method. If yes, call the error.handle method and return its response.
Check if a status page is defined for the error.status code. If yes, render the status page.
Otherwise, render the exception using content negotiation renderers.

If you want to handle a specific exception differently, you can do that inside the handle method. Make sure to use the ctx.response.send method to send a response, since the return value from the handle method is discarded.

import { errors } from '@vinejs/vine'

async handle(error: unknown, ctx: HttpContext) {
  if (error instanceof errors.E_VALIDATION_EXCEPTION) {
    ctx.response.status(422).send(error.messages)
    return
  }
  
  return super.handle(error, ctx)
}

Status pages

Status pages are a collection of templates you want to render for a given or a range of status codes.

The range of status codes can be defined as a string expression. Two dots separate the starting and the ending status codes (..).

If you are creating a JSON server, you may not need status pages.

import { StatusPageRange, StatusPageRenderer } from '@adonisjs/http-server/types'

export default class HttpExceptionHandler extends ExceptionHandler {
  protected statusPages: Record<StatusPageRange, StatusPageRenderer> = {
    '404': (_, { view }) => view.render('errors/not-found'),
    '500..599': (_, { view }) => view.render('errors/server-error')
  }
}

Debug mode

The content negotiation renderers handle exceptions that are not self-handled and not converted to a status page.

The content negotiation renderers have support for debug mode. They can parse and pretty-print errors in debug mode using the Youch npm package.

You can toggle the debug mode using the debug property on the exceptions handler class. However, turning off the debug mode in production is recommended, as it exposes sensitive information about your app.

export default class HttpExceptionHandler extends ExceptionHandler {
  protected debug = !app.inProduction
}

Reporting exceptions

The report method on the exceptions handler class handles reporting of exceptions.

The method receives the error as the first argument and the HTTP context as the second argument. You should not write a response from the report method and use the context only to read the request information.

Logging exceptions

All exceptions are reported using the logger by default.

Exceptions with status codes in the 400..499 range are logged in the warning level.
Exceptions with the status code >=500 are logged in the error level.
All other exceptions are logged in the info level.

You can add custom properties to the log messages by returning an object from the context method.

export default class HttpExceptionHandler extends ExceptionHandler {
  protected context(ctx: HttpContext) {
    return {
      requestId: ctx.requestId,
      userId: ctx.auth.user?.id,
      ip: ctx.request.ip(),
    }
  }
}

Ignoring status codes

You can ignore exceptions from being reported by defining an array of status codes via the ignoreStatuses property.

export default class HttpExceptionHandler extends ExceptionHandler {
  protected ignoreStatuses = [
    401,
    400,
    422,
    403,
  ]
}

Ignoring errors

You can also ignore exceptions by defining an array of error codes or error classes to ignore.

import { errors } from '@adonisjs/core'
import { errors as sessionErrors } from '@adonisjs/session'

export default class HttpExceptionHandler extends ExceptionHandler {
  protected ignoreCodes = [
    'E_ROUTE_NOT_FOUND',
    'E_INVALID_SESSION'
  ]
}

An array of exception classes can be ignored using the ignoreExceptions property.

import { errors } from '@adonisjs/core'
import { errors as sessionErrors } from '@adonisjs/session'

export default class HttpExceptionHandler extends ExceptionHandler {
  protected ignoreExceptions = [
    errors.E_ROUTE_NOT_FOUND,
    sessionErrors.E_INVALID_SESSION,
  ]
}

Custom shouldReport method

The logic to ignore status codes or exceptions is written inside the shouldReport method. If needed, you can override this method and define your custom logic for ignoring exceptions.

import { HttpError } from '@adonisjs/core/types/http'

export default class HttpExceptionHandler extends ExceptionHandler {
  protected shouldReport(error: HttpError) {
    // return a boolean
  }
}

Custom exceptions

You can create an exception class using the make:exception ace command. An exception extends the Exception class from the @adonisjs/core package.

Defining the `handle` method

To self-handle the exception, you can define the handle method on the exception class. This method should convert an error to an HTTP response using the ctx.response.send method.

The error.handle method receives an instance of the error as the first argument and the HTTP context as the second argument.

import { Exception } from '@adonisjs/core'
import { HttpContext } from '@adonisjs/core/http'

export default class UnAuthorizedException extends Exception {
  async handle(error: this, ctx: HttpContext) {
    ctx.response.status(error.status).send(error.message)
  }
}

Define the `report` method

You can implement the report method on the exception class to self-handle the exception reporting. The report method receives an instance of the error as the first argument and the HTTP context as the second argument.

import { Exception } from '@adonisjs/core'
import { HttpContext } from '@adonisjs/core/http'

export default class UnAuthorizedException extends Exception {
  async report(error: this, ctx: HttpContext) {
    ctx.logger.error({ err: err }, error.message)
  }
}

Narrowing down the error type

The framework core and other official packages exports the exceptions raised by them. You can verify if an error is an instance of a specific exception using the instanceof check. For example:

import { errors } from '@adonisjs/core'

try {
  router.builder().make('articles.index')
} catch (error: unknown) {
  if (error instanceof errors.E_CANNOT_LOOKUP_ROUTE) {
    // handle error
  }
}

Known errors

Please check the exceptions reference guide to view the list of known errors.