How To Upload Files With GraphQl And NestJs

#node #graphql #api #nest

Quick demonstration on using GraphQL and Nestjs to upload files (NestJs Code First Approch)

Overview

Hi 👋 You, Today, I'm going to discuss how to upload files using graphql. You may already be familiar with how to upload files using the Rest API, but now you tried Graphql and you're wondering how to upload your cat pictures.

If you're using Nest Js and the Code-first GraphQL approch this guide is for you

Setup

Let's start by installing our dependencies

npm i @nestjs/graphql @nestjs/apollo graphql apollo-server-express graphql-upload@14
yarn add @nestjs/graphql @nestjs/apollo graphql apollo-server-express graphql-upload@14

Now everything is installed go to your app.module.ts file and import ApolloDriver, ApolloDriverConfig & GraphQLModule.

import { ApolloDriver, ApolloDriverConfig } from '@nestjs/apollo';
import { GraphQLModule } from '@nestjs/graphql';

Then add GraphQLModule config to the App module imports.

@Module({
imports: [
  GraphQLModule.forRoot<ApolloDriverConfig>({
  driver: ApolloDriver,
  autoSchemaFile: join(process.cwd(), 'src/schema.gql'),
 }),
],

Lets generate our graphql code now by using nest cli in our terminal.

nest g resource cats

Now Select GraphQL (code first)

? What transport layer do you use?
  REST API
  GraphQL (code first)
  GraphQL (schema first)
  Microservice (non-HTTP)
  WebSockets

This will create a folder inside you src Directory called cats.

Let's Code

Now let's start by writing our mutation to create a cat object with an image

let's start by editing our createCatInput which is imported by our createCatmutation

@InputType()
export class CreateCatInput {
  @Field(() => Int, { description: 'Example field (placeholder)' })
  exampleField: number;
}

Our cat will have these properties name, breed & image

Create a file upload type that we can use for our image field which look like this

import { Stream } from 'stream';

export interface FileUpload {
  filename: string;
  mimetype: string;
  encoding: string;
  createReadStream: () => Stream;
}

Now Add The Fields With GraphQLUpload Scalar Type wich is imported from our package graphql-upload which gives us support for GraphQL multipart requests.

import * as GraphQLUpload from 'graphql-upload/GraphQLUpload.js';

@InputType()
export class CreateCatInput {
  @Field(() => String)
  name: string;
  @Field(() => String)
  breed: string;
  @Field(() => GraphQLUpload)
  image: Promise<FileUpload>;
}

Then head to the cat entity and create a similar type and modify the image field as string so we can return just the filename

@ObjectType()
export class Cat {
  @Field(() => String)
  name: string;
  @Field(() => String)
  breed: string;
  @Field(() => String)
  image: string;
}

Ok now we go to our cats.service.ts where we can handle our image.

create({ breed, name, image }: CreateCatInput) {
  // your code goes here
}

We will return the breed and name precisely as we received them. readable stream ( image ) go ahead and create a new folder, you can name it upload,we will save our images inside it.

async create({ breed, name, image }: CreateCatInput) {
  const { createReadStream, filename } = await image;
  return new Promise(async (resolve) => {
  createReadStream()
   .pipe(createWriteStream(join(process.cwd(), `./src/upload/${filename}`)))
   .on('finish', () =>
     resolve({
      breed,
      name,
      image: filename,
     }),
   )
   .on('error',() => {
       new HttpException('Could not save image', HttpStatus.BAD_REQUEST);
    });
  });
}

Finally go to app.module.ts and add GraphQLUpload Middleware

import * as graphqlUploadExpress from 'graphql-upload/graphqlUploadExpress.js';

const app = await NestFactory.create(AppModule);
app.use(graphqlUploadExpress({ maxFileSize: 1000000, maxFiles: 10 }));
await app.listen(4000);

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Top comments (5)

ChamaraPW • Sep 28 '22 • Edited

I followed this artical to create fileupload end point but getting this error createReadStream is not a function

Amine Elbarry • Oct 11 '22

can you share your code with me i can help you with that

Jacob Brasil • Aug 24 '23

I'm having an issue where the image is an empty file with the correct name in .src/upload, and when I log the readStream, the length is 0. I have tried with multiple images, any ideas why this could be?