File Upload using Angular 12 and Node.js Express example

In this tutorial, I will show you way to build Angular 12 with Node.js Express: File/Image upload & download example.

Other versions:
File Upload using Angular 8 and Node.js
File Upload using Angular 10 and Node.js
File Upload using Angular 11 and Node.js

More Practice:
Angular + Node.js Express + MySQL example
Angular + Node.js Express + PostgreSQL example
Angular + Node.js Express + MongoDB example
Angular + Node.js Express: JWT Authentication & Authorization example
Server side Pagination with Node.js and Angular


Overview

We’re gonna create a full-stack Angular 12 + Node.js: File/Image upload with Express Rest APIs, in that user can:

  • see the upload process (percentage)
  • view all uploaded files/images
  • download by clicking on the file name

file-upload-angular-12-node-js-example

All uploaded files will be saved in uploads folder:

file-upload-angular-12-node-js-express-example-upload-folder

If you want to upload multiple files at once like this:

angular-12-multiple-file-upload-progress-bar-example-bootstrap

You can find the instruction here:
Angular 12 Multiple Files upload example with Progress Bar

Or working with GCS:
Node.js Express File Upload to Google Cloud Storage example

If you want to use Angular Material like this:

angular-material-12-file-upload-example-progress-bar

Please visit: Angular Material 12 File upload example with progress bar

Technology

Server:

  • express 4.17.1
  • multer 1.4.2
  • cors 2.8.5

Client:

  • Angular 12
  • RxJS 6
  • Bootstrap 4

Node.js Express Rest APIs for File Upload & Storage

Node.js Server will provide APIs:

MethodsUrlsActions
POST/uploadupload a File
GET/filesget List of Files (name & url)
GET/files/[filename]download a File

This is the project structure:

file-upload-angular-12-node-js-express-example-server-project-structure

resources/static/assets/uploads: folder for storing uploaded files.
middleware/upload.js: initializes Multer Storage engine and defines middleware function to save uploaded files in uploads folder.
file.controller.js exports Rest APIs: POST a file, GET all files’ information, download a File with url.
routes/index.js: defines routes for endpoints that is called from HTTP Client, use controller to handle requests.
server.js: initializes routes, runs Express app.

You can find Step by Step to implement the Node.js Express Server (with Github) at:
Node.js Express File Upload Rest API example using Multer

Or working with GCS:
Node.js Express File Upload to Google Cloud Storage example

Setup Angular 12 File Upload Project

Let’s open cmd and use Angular CLI to create a new Angular 12 Project as following command:

ng new Angular12FileUpload
? Would you like to add Angular routing? No
? Which stylesheet format would you like to use? CSS

We also need to generate some Components and Services:

ng g s services/file-upload
ng g c components/file-upload

Now you can see that our project directory structure looks like this.

Angular 12 Project Structure

file-upload-angular-12-node-js-express-example-client-project-structure

Let me explain it briefly.

– We import necessary library, components in app.module.ts.
file-upload.service provides methods to save File and get Files from Rest API Server using HttpClient.
file-upload.component contains upload form, progress bar, display of list files.
app.component is the container that we embed all components.
index.html for importing the Bootstrap.

Set up App Module for HttpClient

Open app.module.ts and import HttpClientModule:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';

import { AppComponent } from './app.component';
import { FileUploadComponent } from './components/file-upload/file-upload.component';

@NgModule({
  declarations: [
    AppComponent,
    FileUploadComponent
  ],
  imports: [
    BrowserModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Add Bootstrap to the project

Open index.html and add following line into <head> tag:

<!DOCTYPE html>
<html lang="en">
  <head>
    ...
    <link type="text/css" rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" />
  </head>
  ...
</html>

Create Angular Service for Upload Files

This service will use Angular HttpClient to send HTTP requests.
There are 2 functions:

  • upload(file): returns Observable<HttpEvent<any>> that we’re gonna use for tracking progress
  • getFiles(): returns a list of Files’ information as Observable object

services/file-upload.service.ts

import { Injectable } from '@angular/core';
import { HttpClient, HttpRequest, HttpEvent } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class FileUploadService {
  private baseUrl = 'http://localhost:8080';

  constructor(private http: HttpClient) { }

  upload(file: File): Observable<HttpEvent<any>> {
    const formData: FormData = new FormData();

    formData.append('file', file);

    const req = new HttpRequest('POST', `${this.baseUrl}/upload`, formData, {
      reportProgress: true,
      responseType: 'json'
    });

    return this.http.request(req);
  }

  getFiles(): Observable<any> {
    return this.http.get(`${this.baseUrl}/files`);
  }
}

FormData is a data structure that can be used to store key-value pairs. We use it to build an object which corresponds to an HTML form with append() method.

– We set reportProgress: true to exposes progress events. Notice that this progress event are expensive (change detection for each event), so you should only use when you want to monitor it.

– We call the request(PostRequest) & get() method of HttpClient to send an HTTP POST & Get request to the Spring Boot File Upload server.

Create Component for Upload Files

Let’s create a File Upload UI with Progress Bar, Card, Button and Message.

First we need to use the following imports:

file-upload.component.ts

import { Component, OnInit } from '@angular/core';
import { HttpEventType, HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs';
import { FileUploadService } from 'src/app/services/file-upload.service';

Then we define the some variables and inject FileUploadService as follows:

export class FileUploadComponent implements OnInit {

  selectedFiles?: FileList;
  currentFile?: File;
  progress = 0;
  message = '';

  fileInfos?: Observable<any>;

  constructor(private uploadService: FileUploadService) { }

}

Next we define selectFile() method. It helps us to get the selected Files.

selectFile(event: any): void {
  this.selectedFiles = event.target.files;
}

Next we write upload() method for upload file:

export class FileUploadComponent implements OnInit {
  selectedFiles?: FileList;
  currentFile?: File;
  progress = 0;
  message = '';

  fileInfos?: Observable<any>;

  constructor(private uploadService: FileUploadService) { }

  selectFile(event: any): void {
    this.selectedFiles = event.target.files;
  }

  upload(): void {
    this.progress = 0;

    if (this.selectedFiles) {
      const file: File | null = this.selectedFiles.item(0);

      if (file) {
        this.currentFile = file;

        this.uploadService.upload(this.currentFile).subscribe(
          (event: any) => {
            if (event.type === HttpEventType.UploadProgress) {
              this.progress = Math.round(100 * event.loaded / event.total);
            } else if (event instanceof HttpResponse) {
              this.message = event.body.message;
              this.fileInfos = this.uploadService.getFiles();
            }
          },
          (err: any) => {
            console.log(err);
            this.progress = 0;

            if (err.error && err.error.message) {
              this.message = err.error.message;
            } else {
              this.message = 'Could not upload the file!';
            }

            this.currentFile = undefined;
          });

      }

      this.selectedFiles = undefined;
    }
  }
}

We use selectedFiles for accessing current File as the first Item. Then we call uploadService.upload() method on the currentFile.

The progress will be calculated basing on event.loaded and event.total.
If the transmission is done, the event will be a HttpResponse object. At this time, we call uploadService.getFiles() to get the files’ information and assign the result to fileInfos variable.

We also need to do this work in ngOnInit() method:

ngOnInit(): void {
  this.fileInfos = this.uploadService.getFiles();
}

Now we create the HTML template of the Upload File UI. Add the following content to file-upload.component.html file:

<div class="row">
  <div class="col-8">
    <label class="btn btn-default p-0">
      <input type="file" (change)="selectFile($event)" />
    </label>
  </div>

  <div class="col-4">
    <button class="btn btn-success btn-sm" [disabled]="!selectedFiles" (click)="upload()">
      Upload
    </button>
  </div>
</div>

<div *ngIf="currentFile" class="progress my-3">
  <div
    class="progress-bar progress-bar-info progress-bar-striped"
    role="progressbar"
    attr.aria-valuenow="{{ progress }}"
    aria-valuemin="0"
    aria-valuemax="100"
    [ngStyle]="{ width: progress + '%' }"
  >
    {{ progress }}%
  </div>
</div>

<div *ngIf="message" class="alert alert-secondary" role="alert">{{ message }}</div>

<div class="card mt-3">
  <div class="card-header">List of Files</div>
  <ul
    class="list-group list-group-flush"
    *ngFor="let file of fileInfos | async"
  >
    <li class="list-group-item">
      <a href="{{ file.url }}">{{ file.name }}</a>
    </li>
  </ul>
</div>

Add Upload File Component to App Component

Open app.component.html and embed the FileUpload Component with <app-file-upload> tag.

<div class="container" style="width:600px">
  <div class="my-3">
    <h3>bezkoder.com</h3>
    <h4>{{ title }}</h4>
  </div>

  <app-file-upload></app-file-upload>
</div>

app.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Angular 12 File Upload';
}

Run the App

First we need to create uploads folder with the path resources/static/assets (on server side). Run Node.js Server with command: node server.js.

Because we configure CORS for origin: http://localhost:8081, so you need to run Angular 12 Client with command:
ng serve --port 8081

Open Browser with url http://localhost:8081/ and check the result.

Further Reading

Fullstack:
Angular + Node.js Express + MySQL example
Angular + Node.js Express + PostgreSQL example
Angular + Node.js Express + MongoDB example
Angular + Node.js Express: JWT Authentication & Authorization example
Server side Pagination with Node.js and Angular

Conclusion

Today we’re learned how to build File Upload and Download example using Angular 12 and Node.js Express. We also provide the ability to show list of files, upload progress using Bootstrap, and to download file from the server.

You can find Step by Step to implement the Node.js Server at:
Node.js Express File Upload Rest API example using Multer

If you want to upload multiple files at once like this:

angular-12-multiple-file-upload-progress-bar-example-bootstrap

You can find the instruction here:
Angular 12 Multiple Files upload example with Progress Bar

Or upload file to GCS:
Node.js Express File Upload to Google Cloud Storage example

You will want to know how to run both projects in one place:
How to Integrate Angular with Node.js Restful Services

Source Code

The source code for the Angular 12 Client is uploaded to Github.

Or using Angular Material:
Angular Material 12 File upload example with progress bar

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