Added validation pipe

nest-graph-ql/package.json

@@ -26,6 +26,7 @@
     "@nestjs/mongoose": "^6.1.2",
     "@nestjs/platform-express": "^6.0.0",
     "apollo-server-express": "^2.7.0-alpha.3",
+    "class-transformer": "^0.2.3",
     "graphql": "^14.4.1",
     "graphql-tools": "^4.0.5",
     "mongoose": "^5.6.2",

nest-graph-ql/src/items/dto/create-item.dto.ts

@@ -1,13 +1,19 @@
 import { ObjectType, Field, Int, ID } from 'type-graphql';
+import { IsString, IsNotEmpty, IsNumber } from 'class-validator';
 
 @ObjectType()
 export class ItemType {
     @Field(() => ID)
+    @IsString()
     readonly id: string;
     @Field()
+    @IsString()
+    @IsNotEmpty()
     readonly title: string;
     @Field(() => Int)
+    @IsNumber()
     readonly price: number;
     @Field()
+    @IsString()
     readonly description: string;
 }

nest-graph-ql/src/main.ts

@@ -1,8 +1,10 @@
+import { ValidationPipe } from '@nestjs/common';
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
+  app.useGlobalPipes(new ValidationPipe());
   await app.listen(3000);
 }
 bootstrap();