feat: Added use422ForValidationErrors.

Author: ShogunPanda

README.md

@@ -23,6 +23,7 @@ Register as a plugin, optional providing any of the following options:
 
 - `handle404Errors`: If to set an handler via `setNotFoundHandler`.
 - `hideUnhandledErrors`: If to hide unhandled server errors or returning to the client including stack information. Default is to hide errors when `NODE_ENV` environment variable is `production`.
+- `use422ForValidationErrors`: If to return `422` (`Unprocessable Entity`) instead of `400` (`Bad Request`) in case of validation errors.
 - `convertValidationErrors`: Convert validation errors to a structured human readable object. Default is `true`.
 - `convertResponsesValidationErrors`: Convert response validation errors to a structured human readable object. Default is to enable when `NODE_ENV` environment variable is different from `production`.
 - `allowUndeclaredResponses`: When converting response validation errors, allow responses that have no schema defined instead of throwing an error.

src/handlers.ts

@@ -1,18 +1,19 @@
 import { FastifyError, FastifyReply, FastifyRequest } from 'fastify'
 import {
-  addAdditionalProperties,
   BadRequestError,
   HttpError,
-  InternalServerError,
   INTERNAL_SERVER_ERROR,
-  messagesByCodes,
+  InternalServerError,
   NotFoundError,
-  serializeError,
-  UnsupportedMediaTypeError
+  UnprocessableEntityError,
+  UnsupportedMediaTypeError,
+  addAdditionalProperties,
+  messagesByCodes,
+  serializeError
 } from 'http-errors-enhanced'
-import { GenericObject, kHttpErrorsEnhancedConfiguration, NodeError, RequestSection } from './interfaces.js'
+import { GenericObject, NodeError, RequestSection, kHttpErrorsEnhancedConfiguration } from './interfaces.js'
 import { upperFirst } from './utils.js'
-import { convertValidationErrors, validationMessagesFormatters, ValidationResult } from './validation.js'
+import { ValidationResult, convertValidationErrors, validationMessagesFormatters } from './validation.js'
 
 export function handleNotFoundError(request: FastifyRequest, reply: FastifyReply): void {
   handleErrors(new NotFoundError('Not found.'), request, reply)
@@ -26,7 +27,11 @@ export function handleValidationError(error: FastifyError, request: FastifyReque
   */
   const section = error.message.match(/^\w+/)![0] as RequestSection
 
-  return new BadRequestError('One or more validations failed trying to process your request.', {
+  const Klass = request[kHttpErrorsEnhancedConfiguration]?.use422ForValidationErrors
+    ? UnprocessableEntityError
+    : BadRequestError
+
+  return new Klass('One or more validations failed trying to process your request.', {
     failedValidations: convertValidationErrors(
       section,
       Reflect.get(request, section),

src/index.ts

@@ -23,6 +23,7 @@ export const plugin = fastifyPlugin(
       convertValidationErrors: options.convertValidationErrors ?? true,
       responseValidatorCustomizer: options.responseValidatorCustomizer,
       allowUndeclaredResponses: options.allowUndeclaredResponses ?? false,
+      use422ForValidationErrors: options.use422ForValidationErrors ?? false,
       preHandler: typeof options.preHandler === 'function' ? options.preHandler : undefined
     }
 

src/interfaces.ts

@@ -8,6 +8,7 @@ export interface Configuration {
   hideUnhandledErrors?: boolean
   convertValidationErrors?: boolean
   allowUndeclaredResponses?: boolean
+  use422ForValidationErrors?: boolean
   responseValidatorCustomizer?: (ajv: Ajv) => void
   preHandler?: (error: FastifyError | Error) => Error
 }

test/index.test.ts

@@ -2,16 +2,17 @@
 
 import fastify, { FastifyInstance, FastifyPluginOptions, FastifyReply, FastifyRequest } from 'fastify'
 import {
-  BadGatewayError,
   BAD_GATEWAY,
   BAD_REQUEST,
-  createError,
+  BadGatewayError,
   INTERNAL_SERVER_ERROR,
   NOT_FOUND,
-  UNSUPPORTED_MEDIA_TYPE
+  UNPROCESSABLE_ENTITY,
+  UNSUPPORTED_MEDIA_TYPE,
+  createError
 } from 'http-errors-enhanced'
 import t from 'tap'
-import { handleErrors, plugin as fastifyHttpErrorsEnhanced } from '../src/index.js'
+import { plugin as fastifyHttpErrorsEnhanced, handleErrors } from '../src/index.js'
 
 type Callback = () => void
 
@@ -475,6 +476,25 @@ t.test('Plugin', t => {
       })
     })
 
+    t.test('should use 422 if requested to', async t => {
+      const server = await buildServer({ use422ForValidationErrors: true })
+
+      const response = await server.inject({
+        method: 'POST',
+        url: '/validated/abc',
+        headers: { 'x-header': '123' },
+        payload: []
+      })
+
+      t.equal(response.statusCode, UNPROCESSABLE_ENTITY)
+      t.same(JSON.parse(response.payload), {
+        statusCode: UNPROCESSABLE_ENTITY,
+        error: 'Unprocessable Entity',
+        message: 'One or more validations failed trying to process your request.',
+        failedValidations: { params: { id: 'must be a valid number' } }
+      })
+    })
+
     t.test('should validate querystring', async t => {
       const server = await buildServer()