feature(@nestjs/common) validation pipe

Author: kamilmysliwiec

package.json

@@ -24,6 +24,8 @@
     "@nestjs/microservices": "^4.0.0",
     "@nestjs/testing": "^4.0.0",
     "@nestjs/websockets": "^4.0.0",
+    "class-transformer": "^0.1.8",
+    "class-validator": "^0.7.3",
     "cli-color": "^1.1.0",
     "engine.io-client": "^3.1.1",
     "express": "^4.16.2",

src/common/index.ts

@@ -29,4 +29,5 @@ export {
     WsExceptionFilter,
     NestInterceptor,
 } from './interfaces';
+export * from './pipes';
 export * from './services/logger.service';

src/common/pipes/index.ts

@@ -0,0 +1 @@
+export * from './validation.pipe';

src/common/pipes/validation.pipe.ts

@@ -0,0 +1,30 @@
+import { HttpException } from '@nestjs/core';
+import {
+	PipeTransform,
+	Pipe,
+	ArgumentMetadata,
+	HttpStatus,
+} from '@nestjs/common';
+import { validate } from 'class-validator';
+import { plainToClass } from 'class-transformer';
+
+@Pipe()
+export class ValidationPipe implements PipeTransform<any> {
+	public async transform(value, metadata: ArgumentMetadata) {
+		const { metatype } = metadata;
+		if (!metatype || !this.toValidate(metatype)) {
+			return value;
+		}
+		const entity = plainToClass(metatype, value);
+		const errors = await validate(entity);
+		if (errors.length > 0) {
+			throw new HttpException('Validation failed', HttpStatus.BAD_REQUEST);
+		}
+		return entity;
+	}
+
+	private toValidate(metatype): boolean {
+		const types = [String, Boolean, Number, Array, Object];
+		return !types.find(type => metatype === type);
+	}
+}

src/common/test/pipes/validation.pipe.spec.ts

@@ -0,0 +1,48 @@
+import * as sinon from 'sinon';
+import { expect } from 'chai';
+import { ArgumentMetadata } from './../../interfaces';
+import { IsString } from 'class-validator';
+import { ValidationPipe } from './../../pipes/validation.pipe';
+
+class TestModel {
+	constructor() {}
+	@IsString() public prop1: string;
+
+	@IsString() public prop2: string;
+}
+
+describe('ValidationPipe', () => {
+	let target: ValidationPipe;
+	const metadata: ArgumentMetadata = {
+		type: 'body',
+		metatype: TestModel,
+		data: '',
+	};
+	beforeEach(() => {
+		target = new ValidationPipe();
+	});
+	describe('transform', () => {
+		describe('when metadata is empty or undefined', () => {
+			it('should return the value unchanged', async () => {
+				const testObj = { prop1: 'value1', prop2: 'value2' };
+				expect(await target.transform(testObj, {} as any)).to.equal(testObj);
+				expect(await target.transform(testObj, {} as any)).to.not.be.instanceOf(
+					TestModel,
+				);
+			});
+		});
+		describe('when metadata contains a class', () => {
+			it('should return an instance of the class', async () => {
+				const testObj = { prop1: 'value1', prop2: 'value2' };
+				const result = await target.transform(testObj, metadata);
+				expect(result).to.be.instanceOf(TestModel);
+			});
+		});
+		describe('when validation vails', () => {
+			it('should throw an error', async () => {
+				const testObj = { prop1: 'value1' };
+				return expect(target.transform(testObj, metadata)).to.be.rejected;
+			});
+		});
+	});
+});

tslint.json

@@ -12,6 +12,7 @@
             true,
             "single"
         ],
+        "indent": false,
         "ordered-imports": [
             false
         ],