Skip to main content

NestJS File Upload

In this article, we are going to understand the steps to create a file uploading endpoint in the NestJS application.

Key Features In NestJS File Upload:

Let us know some key features of NestJS file upload before implementing a sample application.
FileInterceptor:
The 'FileInterceptor' will be decorated on top of the file upload endpoint. This interceptor will read single file data from the form posted to the endpoint.
export declare function FilesInterceptor(fieldName: string, localOptions?: MulterOptions): Type<NestInterceptor>;
Here we can observe the 'fieldName' first input parameter this value should be a match with our 'name' attribute value on the form file input field. So our interceptor read our files that are attached to the file input field. Another input parameter of 'MulterOptions' that provides configuration like file destination path, customizing file name, etc.
FilesInterceptor:
The 'FilesInterceptor' will be decorated on top of the file upload endpoint. This interceptor will read all the files from the posted to the endpoint.
export declare function FilesInterceptor(fieldName: string, maxCount?: number, localOptions?: MulterOptions): Type<NestInterceptor>
FileFieldsInterceptor:
The 'FileFieldInterceptor' will be decorated on top of the file upload endpoint. But this interceptor will helpful when our form data contains multiple file input fields.
export declare function FileFieldsInterceptor(uploadFields: MulterField[], localOptions?: MulterOptions): Type<NestInterceptor>
UploadedFiles:
This 'UploadedFiles' type will be used for the endpoint to grab the file information inside of the NestJS endpoint.

Create A Sample NestJS Application:

Let's understand step by step implementation authentication in NestJs application, so let's begin our journey by creating a sample application.
Command To Install CLI:
npm i -g @nestjs/cli
Command To Create NestJS App:
nest new your_project_name

File Upload Endpoint:

Let's create a file upload NestJS endpoint.
src/app.controller.ts:
import {
  Controller,
  Post,
  UploadedFiles,
  UseInterceptors,
} from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';

@Controller()
export class AppController {
  @Post('file-upload')
  @UseInterceptors(FileInterceptor('picture', { dest: './images/' }))
  uploadfile(@UploadedFiles() files): string {
    return 'success';
  }
}
  • (Line: 12) Endpoint decorated with interceptor 'FileInterceptor' that loads from the '@nestjs/platform-express'. This 'FileInterceptor' captures the files from the form submitted to this endpoint. For 'FileInterceptor' first parameter is form filed name in our example 'picture'. Second parameter is like configuration one such here we configured is 'dest' where we specifies the folder path to save the uploaded files. If the specified folder doesn't exist NestJS automatically creates folder and save the file into it.
  • (Line: 13) The '@UploadedFiles()' type that loads from the '@nestjs/common', this type help to fetch all the information about the files uploaded into the action method.

Html And Javascript Form For File Uploading:

Now let's create separate folder like seperate project that will consume our NestJS file upload endpoint. You can create project of Angular, Vue, React, etc any javascript library to consume our NestJS endpoint. In this sample i will use plain javascript code to consume the endpoint.
Your_New_Project_Path/index.html:
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <title>Page Title</title>
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link
      href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0-beta1/dist/css/bootstrap.min.css"
      rel="stylesheet"
      integrity="sha384-giJF6kkoqNQ00vy+HMDP7azOuL0xtbfIcaT9wjKHr8RbDVddVHyTfAAsrekwKmP1"
      crossorigin="anonymous"
    />
  </head>
  <body>
    <form onsubmit="fileUpload(this);return false;">
      <div class="mb-3">
        <label for="formFile" class="form-label"
          >Upload File</label
        >
        <input class="form-control" name="picture" type="file" id="formFile" />
      </div>
      <div>
          <button class="btn btn-primary" type="submit">Upload File</button>
      </div>
    </form>
    <script src="main.js"></script>
  </body>
</html>
(Line: 8-13) Added bootstrap link for styling our form.
(Line: 16) Register form 'onSubmit' event with our custom javascript method 'fileUpload' this method contains our javascript logic to invoke the file upload endpoint. The statement here 'return false' will stop the page reloading on clicking the submitting form.
(Line: 21) Rendered file input field. One important thing here is "name=picture" this 'name' attribute value should match with the first parameter in our 'FileInterceptor'.
Your_New_Project_Path/main.js:
async function fileUpload(formElement) {
  const formData = new FormData(formElement);
  try {
    const response = await fetch("http://localhost:3000/file-upload", {
      method: "POST",
      body: formData,
      dataType:"jsonp"
    });

    if (response.status === 200 || response.status === 201) {
      alert("successfully uploaded file");
    } else {
      alert("failed to upload");
    }
  } catch (e) {
      console.log(e);
    alert("some error occured while uploading file");
  }
}
  • (Line: 2) Initializing 'FormData' by sending our Html Form as input so that it can grab all the form values and post them to the endpoint.
  • Here we invoking our NestJS file upload endpoint by posting our form data as 'body'.

Enable Cors In NestJS Application:

To upload to our application we need to enable cors(cross-site origin issue).
src/main.ts:
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.enableCors({
    allowedHeaders:"*",
    origin: "*"
  });
  await app.listen(3000);
}
bootstrap();
Now we can upload our files without any issues.
Now we can observe our file got saved with the random name without any file extension like below.

Save File With Custom Name And File Extension:

We observed by default files have been saved with random string without any file extension. Now we will use some configuration to make our file to save with our own custom name with the file extension as well. To do that we will implement the 'storage' property configuration in our 'FileInterceptor'.

On customizing the file name in our endpoint, the 'dest' property that we defined on  'FileInterceptor' won't work anymore. So to specify the file storage path we need to configure it as well inside of the 'storage' property.

So now let's define callback methods one for assigning custom file names and another for specifying the destination path to store the uploaded files.
shared/helper.ts:
export class Helper {
  static customFileName(req, file, cb) {
    const uniqueSuffix = Date.now() + '-' + Math.round(Math.random() * 1e9);
    let fileExtension = "";
    if(file.mimetype.indexOf("jpeg") > -1){
        fileExtension = "jpg"
    }else if(file.mimetype.indexOf("png") > -1){
        fileExtension = "png";
    }
    const originalName = file.originalname.split(".")[0];
    cb(null, originalName + '-' + uniqueSuffix+"."+fileExtension);
  }

  static destinationPath(req, file, cb) {
    cb(null, './images/')
  }
}
  • Here we defined 2 callback methods one to save our own custom name another for destination property. These methods have the same set of input parameters which will be automatically passed by the framework on invoking the upload endpoint.
  • In the 'customFileName' method we are trying to frame the file name like a combination of the original file name and some random string. We can also observe we are defining file extensions also.
  • In the 'destinationPath' method we defined our file storage location because the 'dest' property previously we used won't work anymore when we configured these callback methods to the 'storage' property.
Now let's update our file upload endpoint to use our callback methods.
src/app.controller.ts:
import {
  Controller,
  Post,
  UploadedFiles,
  UseInterceptors,
} from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';
import { diskStorage } from 'multer';
import { Helper } from './shared/helper';

@Controller()
export class AppController {
  @Post('file-upload')
  @UseInterceptors(
    FileInterceptor('picture', {
      storage: diskStorage({
        destination: Helper.destinationPath,
        filename: Helper.customFileName,
      }),
    }),
  )
  uploadfile(@UploadedFiles() files): string {
    return 'success';
  }
}
  • (Line: 8) Imported 'diskStorage' that loads from  'multer' which is a 'node.js' library.
  • Inside of the 'FilteInterceptor', we configured the storage property with 'diskStorage' instance. Inside of the 'diskStorage' instance, we have registered our callback methods.
Now if we test our endpoint, we can observe our custom names will be reflected in our uploaded files.

Use FilesInterceptor To Upload Multiple Files:

First, we need to add 'multiple' attribute to our file input field, so that it enables us to select multiple images.
Your_New_Project_Path/index.html:(Update File Input Field With Multiple Attribute)
<input class="form-control" name="picture" type="file" id="formFile" multiple />
Now instead of using 'FileInterceptor', we need to use 'FilesInterceptor' that has the capability to read an array of multiple files.
src/app.controller.cs:
@Post('file-upload')
@UseInterceptors(
FilesInterceptor('picture',10,{
  storage: diskStorage({
	destination: Helper.destinationPath,
	filename: Helper.customFileName,
  }),
}),
)
uploadfile(@UploadedFiles() files): string {
return 'success';
}
  • The 'FilesInterceptor' also provide us to specify the maximum number of multiple images that can be uploaded. Here in our sample, we specified '10' as a maximum limit to upload.

Use FileFieldsInterceptor To Read Multiple File Input Form Fields:

In form there might be scenarios where we will have multiple file input form fields, so to read the files from multiple file input fields we need to use another interceptor called 'FileFieldsInterceptor'.

Let's update our form to have multiple input file fields as below.
Your_New_Project_Path/index.html:
<div class="mb-3">
<label for="formFile" class="form-label">Picture 1</label>
<input
  class="form-control"
  name="picture1"
  type="file"
  id="formFile"
  multiple
/>
</div>
<div class="mb-3">
<label for="formFile" class="form-label">Picture 2</label>
<input
  class="form-control"
  name="picture2"
  type="file"
  id="formFile"
  multiple
/>
</div>
Now update our file upload endpoint to read multiple file input fields using 'FileFieldsInterceptor'.
src/app.controller.ts:
import {
  Controller,
  Post,
  UploadedFiles,
  UseInterceptors,
} from '@nestjs/common';
import { FileFieldsInterceptor } from '@nestjs/platform-express';
import { diskStorage } from 'multer';
import { Helper } from './shared/helper';

@Controller()
export class AppController {
  @Post('file-upload')
  @UseInterceptors(
    FileFieldsInterceptor(
      [
        {
          name: 'picture1',
          maxCount: 2,
        },
        {
          name: 'picture2',
          maxCount: 1,
        },
      ],
      {
        storage: diskStorage({
          destination: Helper.destinationPath,
          filename: Helper.customFileName,
        }),
      },
    ),
  )
  uploadfile(@UploadedFiles() files): string {
    return 'success';
  }
}
  • Here inside of 'FileFieldsInterceptor' we registered our file input field name attributes like 'picture1' and 'picture2', here we can also specify 'maxCount' to register the max number of multiple images that can be read from each input file field.
That's all about the file upload endpoint in the NestJS application.

Support Me!
Buy Me A Coffee PayPal Me

Wrapping Up:

Hopefully, I think this article delivered some useful information on file upload in the NestJS application. I love to have your feedback, suggestions, and better techniques in the comment section below.

Refer:

Follow Me:

Comments

  1. the static method Helper.DestinationPath is not resolved in run-time, did i do something wrong?

    ReplyDelete
  2. Hey can We get git Repository for this code

    ReplyDelete
  3. How to use for SFTP server upload?

    ReplyDelete

Post a Comment

Popular posts from this blog

Angular 14 Reactive Forms Example

In this article, we will explore the Angular(14) reactive forms with an example. Reactive Forms: Angular reactive forms support model-driven techniques to handle the form's input values. The reactive forms state is immutable, any form filed change creates a new state for the form. Reactive forms are built around observable streams, where form inputs and values are provided as streams of input values, which can be accessed synchronously. Some key notations that involve in reactive forms are like: FormControl - each input element in the form is 'FormControl'. The 'FormControl' tracks the value and validation status of form fields. FormGroup - Track the value and validate the state of the group of 'FormControl'. FormBuilder - Angular service which can be used to create the 'FormGroup' or FormControl instance quickly. Form Array - That can hold infinite form control, this helps to create dynamic forms. Create An Angular(14) Application: Let'

.NET 7 Web API CRUD Using Entity Framework Core

In this article, we are going to implement a sample .NET 7 Web API CRUD using the Entity Framework Core. Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, and desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains programming functions that can be requested via HTTP calls either to fetch or update data for their respective clients. Some of the Key Characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build the REST full services. Install The SQL Server And SQL Management Studio: Let's install the SQL server on our l

ReactJS(v18) JWT Authentication Using HTTP Only Cookie

In this article, we will implement the ReactJS application authentication using the HTTP-only cookie. HTTP Only Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing the JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-ONly cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use the authentication with HTTP-only JWT cookie then we no need to implement the custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To authenticate our client application with JWT HTTP-only cookie, I developed a NetJS(which is a node) Mock API. Check the GitHub link and read the document on G

.NET6 Web API CRUD Operation With Entity Framework Core

In this article, we are going to do a small demo on AspNetCore 6 Web API CRUD operations. What Is Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains a programming function that can be requested via HTTP calls to save or fetch the data for their respective clients. Some of the key characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build REST full services. Create A .NET6 Web API Application: Let's create a .Net6 Web API sample application to accomplish our

Angular 14 State Management CRUD Example With NgRx(14)

In this article, we are going to implement the Angular(14) state management CRUD example with NgRx(14) NgRx Store For State Management: In an angular application to share consistent data between multiple components, we use NgRx state management. Using NgRx state helps to avoid unwanted API calls, easy to maintain consistent data, etc. The main building blocks for the NgRx store are: Actions - NgRx actions represents event to trigger the reducers to save the data into the stores. Reducer - Reducer's pure function, which is used to create a new state on data change. Store - The store is the model or entity that holds the data. Selector - Selector to fetch the slices of data from the store to angular components. Effects - Effects deals with external network calls like API. The effect gets executed based the action performed Ngrx State Management flow: The angular component needs data for binding.  So angular component calls an action that is responsible for invoking the API call.  Aft

Unit Testing Asp.NetCore Web API Using xUnit[.NET6]

In this article, we are going to write test cases to an Asp.NetCore Web API(.NET6) application using the xUnit. xUnit For .NET: The xUnit for .Net is a free, open-source, community-focused unit testing tool for .NET applications. By default .Net also provides a xUnit project template to implement test cases. Unit test cases build upon the 'AAA' formula that means 'Arrange', 'Act' and 'Assert' Arrange - Declaring variables, objects, instantiating mocks, etc. Act - Calling or invoking the method that needs to be tested. Assert - The assert ensures that code behaves as expected means yielding expected output. Create An API And Unit Test Projects: Let's create a .Net6 Web API and xUnit sample applications to accomplish our demo. We can use either Visual Studio 2022 or Visual Studio Code(using .NET CLI commands) to create any.Net6 application. For this demo, I'm using the 'Visual Studio Code'(using the .NET CLI command) editor. Create a fo

Angular 14 Crud Example

In this article, we will implement CRUD operation in the Angular 14 application. Angular: Angular is a framework that can be used to build a single-page application. Angular applications are built with components that make our code simple and clean. Angular components compose of 3 files like TypeScript File(*.ts), Html File(*.html), CSS File(*.cs) Components typescript file and HTML file support 2-way binding which means data flow is bi-directional Component typescript file listens for all HTML events from the HTML file. Create Angular(14) Application: Let's create an Angular(14) application to begin our sample. Make sure to install the Angular CLI tool into our local machine because it provides easy CLI commands to play with the angular application. Command To Install Angular CLI npm install -g @angular/cli Run the below command to create the angular application. Command To Create Angular Application ng new name_of_your_app Note: While creating the app, you will see a noti

Part-1 Angular JWT Authentication Using HTTP Only Cookie[Angular V13]

In this article, we are going to implement a sample angular application authentication using HTTP only cookie that contains a JWT token. HTTP Only JWT Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-Only cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use authentication with HTTP only JWT cookie then we no need to implement custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To implement JWT cookie authentication we need to set up an API. For that, I had created a mock authentication API(Using the NestJS Se

ReactJS(v18) Authentication With JWT AccessToken And Refresh Token

In this article, we are going to do ReactJS(v18) application authentication using the JWT Access Token and Refresh Token. JSON Web Token(JWT): JSON Web Token is a digitally signed and secured token for user validation. The JWT is constructed with 3 important parts: Header Payload Signature Create ReactJS Application: Let's create a ReactJS application to accomplish our demo. npx create-react-app name-of-your-app Configure React Bootstrap Library: Let's install the React Bootstrap library npm install react-bootstrap bootstrap Now add the bootstrap CSS reference in 'index.js'. src/index.js: import 'bootstrap/dist/css/bootstrap.min.css' Create A React Component 'Layout': Let's add a React component like 'Layout' in 'components/shared' folders(new folders). src/components/shared/Layout.js: import Navbar from "react-bootstrap/Navbar"; import { Container } from "react-bootstrap"; import Nav from "react-boot

A Small Guide On NestJS Queues

NestJS Application Queues helps to deal with application scaling and performance challenges. When To Use Queues?: API request that mostly involves in time taking operations like CPU bound operation, doing them synchronously which will result in thread blocking. So to avoid these issues, it is an appropriate way to make the CPU-bound operation separate background job.  In nestjs one of the best solutions for these kinds of tasks is to implement the Queues. For queueing mechanism in the nestjs application most recommended library is '@nestjs/bull'(Bull is nodejs queue library). The 'Bull' depends on Redis cache for data storage like a job. So in this queueing technique, we will create services like 'Producer' and 'Consumer'. The 'Producer' is used to push our jobs into the Redis stores. The consumer will read those jobs(eg: CPU Bound Operations) and process them. So by using this queues technique user requests processed very fastly because actually