[FEAT] Add EnumFallback decorator

README.md

@@ -64,6 +64,12 @@ A package containing overriden class validators.
 
 See [the documentation here](./packages/class-validators).
 
+## NestJS class transformers
+
+A package containing custom class transformers.
+
+See [the documentation here](./packages/class-transformers).
+
 # Contribution
 
 This repository is managed by [Lerna.js](https://lerna.js.org). If you want to contribute, you need to follow these instructions:

package.json

@@ -95,6 +95,7 @@
     "@algoan/nestjs-http-exception-filter": "file:packages/http-exception-filter",
     "@algoan/nestjs-logging-interceptor": "file:packages/logging-interceptor",
     "@algoan/nestjs-pagination": "file:packages/pagination",
-    "@algoan/nestjs-class-validators": "file:packages/class-validators"
+    "@algoan/nestjs-class-validators": "file:packages/class-validators",
+    "@algoan/nestjs-class-transformers": "file:packages/class-transformers"
   }
 }

packages/class-transformers/README.md

@@ -0,0 +1,29 @@
+# Nestjs class transformers
+
+A set of class transformers
+
+## Installation
+
+```bash
+npm install --save @algoan/nestjs-class-validators
+```
+
+## EnumFallback
+
+
+### Usage 
+
+```ts
+export enum UserRole {
+  ADMIN = 'ADMIN',
+  READER = 'READER',
+}
+
+class UserDto {
+  @EnumFallback({
+    type: UserRole,
+    fallback: (value: UserRole) => UserRole.READER // if the role is not "ADMIN" or "READER", then the role will be "READER". 
+  })
+  public role?: UserRole;
+}
+```

packages/class-transformers/jest.config.js

@@ -0,0 +1,8 @@
+module.exports = {
+    ...require('../jest.common'),
+
+    coverageDirectory: "coverage",
+    collectCoverageFrom: ["./src/**/*.ts"],
+
+    rootDir: ".",
+};

packages/class-transformers/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "@algoan/nestjs-class-transformers",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "build": "tsc -p .",
+    "test": "jest"
+  },
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "class-transformer": "^0.5.1",
+    "class-validator": "^0.14.0",
+    "reflect-metadata": "^0.2.1"
+  },
+  "globals": {
+    "ts-jest": {
+      "diagnostics": false,
+      "isolatedModules": true
+    }
+  }
+}

packages/class-transformers/src/enum-fallback.decorator.ts

@@ -0,0 +1,34 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+
+import { ValidationArguments, ValidationOptions, registerDecorator } from 'class-validator';
+
+/**
+ * Checks if a given value is the member of the provided enum and call a fallback function
+ * if the value is invalid
+ */
+export function EnumFallback(enumType: any, fallback: (value: any) => any, validationOptions?: ValidationOptions) {
+  return function (object: Record<string, any>, propertyName: string) {
+    registerDecorator({
+      name: 'enumFallback',
+      target: object.constructor,
+      propertyName,
+      constraints: [enumType, fallback],
+      options: validationOptions,
+      validator: {
+        validate(value: any, args: ValidationArguments) {
+          const [enumTypeValue, fallbackFn] = args.constraints;
+          if (value === undefined || !Object.values(enumTypeValue).includes(value)) {
+            // eslint-disable-next-line
+            const updatedObject = Object.assign({}, args.object, {
+              [propertyName]: fallbackFn(value),
+            });
+            // eslint-disable-next-line
+            Object.assign(args.object, updatedObject);
+          }
+
+          return true;
+        },
+      },
+    });
+  };
+}

packages/class-transformers/src/index.ts

@@ -0,0 +1 @@
+export * from './enum-fallback.decorator';

packages/class-transformers/test/enum-fallback-decorator.test.ts

@@ -0,0 +1,44 @@
+import { EnumFallback } from '../src';
+import { ArgumentMetadata, ValidationPipe } from '@nestjs/common';
+
+enum UserRole {
+  ADMIN = 'ADMIN',
+  READER = 'READER',
+}
+
+class UserDto {
+  @EnumFallback(UserRole, (_value: UserRole) => UserRole.READER)
+  public role?: UserRole;
+}
+
+describe('EnumFallback Decorator', () => {
+  it('should apply the fallback functions when we have an invalid value', async () => {
+    const userDto = new UserDto();
+    userDto.role = 'WRITER' as UserRole;
+
+    let target: ValidationPipe = new ValidationPipe({ transform: true, whitelist: true });
+    const metadata: ArgumentMetadata = {
+      type: 'body',
+      metatype: UserDto,
+      data: '',
+    };
+    const result = await target.transform(userDto, metadata);
+
+    expect(result.role).toEqual(UserRole.READER);
+  });
+
+  it('should not apply the fallback function when the value is valid', async () => {
+    const userDto = new UserDto();
+    userDto.role = UserRole.ADMIN;
+
+    let target: ValidationPipe = new ValidationPipe({ transform: true, whitelist: true });
+    const metadata: ArgumentMetadata = {
+      type: 'body',
+      metatype: UserDto,
+      data: '',
+    };
+    const result = await target.transform(userDto, metadata);
+
+    expect(result.role).toBe(UserRole.ADMIN);
+  });
+});

packages/class-transformers/tsconfig.json

@@ -0,0 +1,15 @@
+{
+    "extends": "../tsconfig.base.json",
+    "compilerOptions": {
+      "declaration": true,
+      "experimentalDecorators": true,
+      "outDir": "dist",
+    },
+    "include": [
+      "./src/**/*",
+      "./test/**/*.ts"
+    ],
+    "exclude": [
+      "node_modules"
+    ]
+  }