feat: Change the way it transforms the errors

The errors now are returned differently, change the code where you perceive the errors, accordingly.

Author: cerpinn

README.md

@@ -10,7 +10,7 @@ The default validation pipe is great, but error it returns is just an array of e
 {
   "statusCode": 400,
   "error": "Bad Request",
-  "message": ["email must be an email", "phone cannot be empty"]
+  "message": ["email must be an email", "phone should not be empty"]
 }
 ```
 
@@ -20,10 +20,25 @@ This package changes the `message` to be an object with field names as keys:
 {
   "statusCode": 400,
   "error": "Bad Request",
-  "message": {
-    "email": ["email must be an email"],
-    "phone": ["phone cannot be empty"]
-  }
+  "message": [
+    {
+      "field": ["email"],
+      "errors": ["email must be an email"]
+    },
+    {
+      "field": ["phone"],
+      "errors": ["phone should not be empty"]
+    }
+  ]
+}
+```
+
+It also works for [nested values](https://github.com/typestack/class-validator#validating-nested-objects):
+
+```json
+{
+  "field": ["nestedObject", "name"],
+  "errors": ["name should not be empty"]
 }
 ```
 
@@ -43,10 +58,10 @@ On NPM:
 npm install @exonest/better-validation-pipe
 ```
 
-## Motivation
+## Usage
 
-This behavior is achievable by passing a custom `exceptionFactory` to the original pipe, but I found myself writing the same exception factory for each one of my projects, so I made this small package.
+Just use it as you would normally use [Nest's built-in validation pipe](https://docs.nestjs.com/techniques/validation#using-the-built-in-validationpipe). You can also pass options to it, just like you would with the built-in one.
 
-## Inspiration
+## Motivation
 
-This is the same way [Laravel](https://laravel.com/docs/master/validation) returns errors; as an object that contains arrays of errors (strings).
+This behavior is achievable by passing a custom `exceptionFactory` to the original pipe, but I found myself writing the same exception factory for each one of my projects, so I made this package to do the job.

package.json

@@ -72,6 +72,8 @@
   },
   "dependencies": {
     "@nestjs/common": "^8.2.0",
+    "class-transformer": "^0.4.0",
+    "class-validator": "^0.13.1",
     "reflect-metadata": "^0.1.13"
   }
 }

src/error-transformer.spec.ts

@@ -0,0 +1,14 @@
+import { transformErrors } from './error-transformer';
+import { exampleErrors } from './example-errors';
+
+describe('Error transformer', () => {
+  it('returns an array of errors with relavant fields', async () => {
+    const transformedErrors = transformErrors(exampleErrors);
+
+    expect(Array.isArray(transformedErrors)).toBe(true);
+    expect(Array.isArray(transformedErrors[0].errors)).toBe(true);
+    expect(typeof transformedErrors[0].errors[0]).toBe('string');
+    expect(Array.isArray(transformedErrors[0].field)).toBe(true);
+    expect(typeof transformedErrors[0].field[0]).toBe('string');
+  });
+});

src/error-transformer.ts

@@ -0,0 +1,38 @@
+import { ValidationError } from '@nestjs/common';
+
+export interface TransformedError {
+  field: string[];
+  errors: string[];
+}
+
+export const transformErrors = (
+  validationErrors: ValidationError[],
+  nest: string[] = []
+) => {
+  return validationErrors.reduce((accumulator: TransformedError[], current) => {
+    accumulator.push(...transformError(current, nest));
+    return accumulator;
+  }, []);
+};
+
+const transformError = (
+  validationError: ValidationError,
+  nest: string[]
+): TransformedError[] => {
+  const op = [];
+
+  if (validationError.constraints) {
+    op.push({
+      field: [...nest, validationError.property],
+      errors: Object.values(validationError.constraints || []),
+    });
+  }
+
+  if (validationError.children?.length) {
+    validationError.children.forEach(child => {
+      op.push(...transformError(child, [...nest, validationError.property]));
+    });
+  }
+
+  return op;
+};

src/example-errors.ts

@@ -0,0 +1,88 @@
+import { ValidationError } from '@nestjs/common';
+
+export const exampleErrors: ValidationError[] = [
+  {
+    target: {
+      description: '',
+      email: '',
+      handle: '',
+      nestedObject: { name: '', phone: '' },
+      title: '',
+    },
+    value: '',
+    property: 'title',
+    children: [],
+    constraints: {
+      minLength: 'title must be longer than or equal to 10 characters',
+    },
+  },
+  {
+    target: {
+      description: '',
+      email: '',
+      handle: '',
+      nestedObject: { name: '', phone: '' },
+      title: '',
+    },
+    value: '',
+    property: 'description',
+    children: [],
+    constraints: { isNotEmpty: 'description should not be empty' },
+  },
+  {
+    target: {
+      description: '',
+      email: '',
+      handle: '',
+      nestedObject: { name: '', phone: '' },
+      title: '',
+    },
+    value: '',
+    property: 'handle',
+    children: [],
+    constraints: { isNotEmpty: 'handle should not be empty' },
+  },
+  {
+    target: {
+      description: '',
+      email: '',
+      handle: '',
+      nestedObject: { name: '', phone: '' },
+      title: '',
+    },
+    value: '',
+    property: 'email',
+    children: [],
+    constraints: { isEmail: 'email must be an email' },
+  },
+  {
+    target: {
+      description: '',
+      email: '',
+      handle: '',
+      nestedObject: { name: '', phone: '' },
+      title: '',
+    },
+    value: { name: '', phone: '' },
+    property: 'nestedObject',
+    children: [
+      {
+        target: { name: '', phone: '' },
+        value: '',
+        property: 'name',
+        children: [],
+        constraints: { isNotEmpty: 'name should not be empty' },
+      },
+      {
+        target: { name: '', phone: '' },
+        value: '',
+        property: 'phone',
+        children: [],
+        constraints: {
+          isPhoneNumber: 'phone must be a valid phone number',
+          isNotEmpty: 'phone should not be empty',
+        },
+      },
+    ],
+  },
+];

src/validation.pipe.ts

@@ -3,17 +3,15 @@ import {
   ValidationPipe as OriginalValidationPipe,
 } from '@nestjs/common';
 import { HttpErrorByCode } from '@nestjs/common/utils/http-error-by-code.util';
+import { transformErrors } from './error-transformer';
 
 export class ValidationPipe extends OriginalValidationPipe {
   public createExceptionFactory() {
     return (validationErrors: ValidationError[] = []) => {
       if (this.isDetailedOutputDisabled) {
         return new HttpErrorByCode[this.errorHttpStatusCode]();
       }
-      const errors: Record<string, unknown> = {};
-      validationErrors.forEach(error => {
-        errors[error.property] = Object.values(error.constraints || {});
-      });
+      const errors = transformErrors(validationErrors);
       return new HttpErrorByCode[this.errorHttpStatusCode](errors);
     };
   }

yarn.lock

@@ -1611,6 +1611,11 @@
   resolved "https://registry.yarnpkg.com/@types/stack-utils/-/stack-utils-1.0.1.tgz#0a851d3bd96498fa25c33ab7278ed3bd65f06c3e"
   integrity sha512-l42BggppR6zLmpfU6fq9HEa2oGPEI8yrSPL3GITjfRInppYFahObbIQOQK3UGxEnyQpltZLaPe75046NOZQikw==
 
+"@types/validator@^13.1.3":
+  version "13.6.6"
+  resolved "https://registry.yarnpkg.com/@types/validator/-/validator-13.6.6.tgz#6e6e2d086148db5ae14851614971b715670cbd52"
+  integrity sha512-+qogUELb4gMhrMjSh/seKmGVvN+uQLfyqJAqYRWqVHsvBsUO2xDBCL8CJ/ZSukbd8vXaoYbpIssAmfLEzzBHEw==
+
 "@types/webpack@^5.0.0":
   version "5.28.0"
   resolved "https://registry.yarnpkg.com/@types/webpack/-/webpack-5.28.0.tgz#78dde06212f038d77e54116cfe69e88ae9ed2c03"
@@ -2593,6 +2598,11 @@ ci-job-number@^1.2.2:
   resolved "https://registry.yarnpkg.com/ci-job-number/-/ci-job-number-1.2.2.tgz#f4e5918fcaeeda95b604f214be7d7d4a961fe0c0"
   integrity sha512-CLOGsVDrVamzv8sXJGaILUVI6dsuAkouJP/n6t+OxLPeeA4DDby7zn9SB6EUpa1H7oIKoE+rMmkW80zYsFfUjA==
 
+class-transformer@^0.4.0:
+  version "0.4.0"
+  resolved "https://registry.yarnpkg.com/class-transformer/-/class-transformer-0.4.0.tgz#b52144117b423c516afb44cc1c76dbad31c2165b"
+  integrity sha512-ETWD/H2TbWbKEi7m9N4Km5+cw1hNcqJSxlSYhsLsNjQzWWiZIYA1zafxpK9PwVfaZ6AqR5rrjPVUBGESm5tQUA==
+
 class-utils@^0.3.5:
   version "0.3.6"
   resolved "https://registry.yarnpkg.com/class-utils/-/class-utils-0.3.6.tgz#f93369ae8b9a7ce02fd41faad0ca83033190c463"
@@ -2603,6 +2613,15 @@ class-utils@^0.3.5:
     isobject "^3.0.0"
     static-extend "^0.1.1"
 
+class-validator@^0.13.1:
+  version "0.13.1"
+  resolved "https://registry.yarnpkg.com/class-validator/-/class-validator-0.13.1.tgz#381b2001ee6b9e05afd133671fbdf760da7dec67"
+  integrity sha512-zWIeYFhUitvAHBwNhDdCRK09hWx+P0HUwFE8US8/CxFpMVzkUK8RJl7yOIE+BVu2lxyPNgeOaFv78tLE47jBIg==
+  dependencies:
+    "@types/validator" "^13.1.3"
+    libphonenumber-js "^1.9.7"
+    validator "^13.5.2"
+
 clean-stack@^2.0.0:
   version "2.2.0"
   resolved "https://registry.yarnpkg.com/clean-stack/-/clean-stack-2.2.0.tgz#ee8472dbb129e727b31e8a10a427dee9dfe4008b"
@@ -5588,6 +5607,11 @@ levn@^0.3.0, levn@~0.3.0:
     prelude-ls "~1.1.2"
     type-check "~0.3.2"
 
+libphonenumber-js@^1.9.7:
+  version "1.9.42"
+  resolved "https://registry.yarnpkg.com/libphonenumber-js/-/libphonenumber-js-1.9.42.tgz#41f41d540f89b6e3fd36de7120ddb57b3a468c77"
+  integrity sha512-UBtU0ylpZPKPT8NLIyQJWj/DToMFxmo3Fm5m6qDc0LATvf0SY0qUhaurCEvukAB9Fo+Ia2Anjzqwoupaa64fXg==
+
 lilconfig@^2.0.3:
   version "2.0.4"
   resolved "https://registry.yarnpkg.com/lilconfig/-/lilconfig-2.0.4.tgz#f4507d043d7058b380b6a8f5cb7bcd4b34cee082"
@@ -8579,6 +8603,11 @@ validate-npm-package-name@^3.0.0:
   dependencies:
     builtins "^1.0.3"
 
+validator@^13.5.2:
+  version "13.7.0"
+  resolved "https://registry.yarnpkg.com/validator/-/validator-13.7.0.tgz#4f9658ba13ba8f3d82ee881d3516489ea85c0857"
+  integrity sha512-nYXQLCBkpJ8X6ltALua9dRrZDHVYxjJ1wgskNt1lH9fzGjs3tgojGSCBjmEPwkWS1y29+DrizMTW19Pr9uB2nw==
+
 vendors@^1.0.3:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/vendors/-/vendors-1.0.4.tgz#e2b800a53e7a29b93506c3cf41100d16c4c4ad8e"