Angular 17 Multiple Images Upload with Preview example

In this tutorial, I will show you way to build Angular 17 Multiple Image Upload with Preview example to Web API/Rest API using FormData and Bootstrap.

More Practice:
Angular 17 + Spring Boot: File upload example
Angular 17 + Node Express: File Upload example
Angular 17 CRUD example with Rest API
Angular 17 Form Validation example
Angular 17 JWT Authentication & Authorization example
– Using Material: Angular Material 17 Image upload with Preview example


Overview

We will create an Angular 17 Multiple Image upload with Preview application in that user can:

  • upload multiple Images
  • see the preview of images that will be uploaded
  • see the upload process (percentage) of all uploading images
  • view all uploaded images
  • download image by clicking on the file name

Here are screenshots of our Angular App:

angular-17-multiple-image-upload-preview-example

List of Images Display with download Urls:

angular-17-multiple-image-upload-preview-example-result

– Show status for each image upload:

angular-17-multiple-image-upload-preview-example-handle-error

Technology

  • Angular 17
  • RxJS 7
  • Bootstrap 4

Rest API for Multiple Image Upload & Storage

Here are Rest APIs that we will use Axios to make HTTP requests:

Methods Urls Actions
POST /upload upload a File
GET /files get List of Files (name & url)
GET /files/[filename] download a File

You can find how to implement the Rest APIs Server at one of following posts:
Node.js Express File Upload Rest API example
Node.js Express File Upload to MongoDB example
Node.js Express File Upload to Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

Setup Angular 17 Project

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

ng new angular-17-multiple-image-upload-preview
? Which stylesheet format would you like to use? CSS
? Do you want to enable Server-Side Rendering (SSR) and Static Site Generation (SSG/Prerendering)? No

We also need to generate some Components and Services:

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

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

Angular 17 Multiple Image upload with Preview Project

angular-17-multiple-image-upload-preview-example-project

Let me explain it briefly.

– We import necessary library in app.config.ts.
file-upload.service provides methods to save File and get Files from Rest Apis Server.
upload-images.component contains image upload for multiple images form, preview, display list of images.
app.component is the container that we embed all components.
index.html or angular.json for importing the Bootstrap.

Set up HttpClient Module

Open app.config.ts and import provideHttpClient from Angular Http Module:

import { ApplicationConfig } from '@angular/core';
import { provideRouter } from '@angular/router';
import { provideHttpClient } from '@angular/common/http';

import { routes } from './app.routes';

export const appConfig: ApplicationConfig = {
  providers: [
    provideRouter(routes),
    provideHttpClient()
  ]
};

Add Bootstrap to the project

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

<!DOCTYPE html>
<html lang="en">
  <head>
    ...
    <link rel="stylesheet" href="https://unpkg.com/[email protected]/dist/css/bootstrap.min.css" />
  </head>
  ...
</html>

Another way is installing Bootstrap module with command: npm install [email protected].
Then add following code into angular.json:

"styles": [
  "node_modules/bootstrap/dist/css/bootstrap.min.css",
  "src/styles.css"
],
"scripts": [
  "node_modules/jquery/dist/jquery.slim.min.js",
  "node_modules/popper.js/dist/umd/popper.min.js",
  "node_modules/bootstrap/dist/js/bootstrap.min.js"
]

Create Angular 17 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 in Image Upload Component
  • 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, {
      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 call the request(PostRequest) & get() method of HttpClient to send an HTTP POST & Get request to the Multiple Files Upload Rest server.

Create Angular 17 Component for Upload Multiple Images

Let’s create a Multiple Images Upload UI with Preview, Card, Button and Message.

First we need to use the following imports:

upload-images.component.ts

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

@Component({
  selector: 'app-upload-images',
  standalone: true,
  imports: [CommonModule],
  templateUrl: './upload-images.component.html',
  styleUrl: './upload-images.component.css',
})
export class UploadImagesComponent implements OnInit { ... }

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

export class UploadImagesComponent implements OnInit {
  selectedFiles?: FileList;
  message: string[] = [];

  previews: string[] = [];
  imageInfos?: Observable<any>;

  constructor(private uploadService: FileUploadService) { }
}

Next we define selectFiles() method. It helps us to get the selected Images that we’re gonna upload.

selectFiles(event: any): void {
  this.message = [];
  this.selectedFiles = event.target.files;

  this.previews = [];
  if (this.selectedFiles && this.selectedFiles[0]) {
    const numberOfFiles = this.selectedFiles.length;
    for (let i = 0; i < numberOfFiles; i++) {
      const reader = new FileReader();

      reader.onload = (e: any) => {
        this.previews.push(e.target.result);
      };

      reader.readAsDataURL(this.selectedFiles[i]);
    }
  }
}

We use FileReader with readAsDataURL() method to get the image preview URL and put it into previews array. This method produces data as a data: URL representing the file’s data as a base64 encoded string. The URL life is tied to the document in the window on which it was created.

Also use selectedFiles array for accessing current selected Files.

Now we iterate over the selected Files above and call upload() method on each file item.

uploadFiles(): void {
  this.message = [];

  if (this.selectedFiles) {
    for (let i = 0; i < this.selectedFiles.length; i++) {
      this.upload(i, this.selectedFiles[i]);
    }
  }
}

Next we define upload() method for uploading each image:

upload(file: File): void {
  if (file) {
    this.uploadService.upload(file).subscribe({
      next: (event: any) => {
        if (event instanceof HttpResponse) {
          const msg = file.name + ': Successful!';
          this.message.push(msg);
          this.imageInfos = this.uploadService.getFiles();
        }
      },
      error: (err: any) => {
        let msg = file.name + ': Failed!';

        if (err.error && err.error.message) {
          msg += ' ' + err.error.message;
        }

        this.message.push(msg);
        this.imageInfos = this.uploadService.getFiles();
      },
    });
  }
}

We call uploadService.upload() method on each file.

If the transmission is done, the event will be a HttpResponse object. At this time, we call uploadService.getFiles() to get the image files’ information and assign the result to imageInfos variable.

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

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

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

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

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


<div>
  @for (preview of previews; track $index) {
  <img [src]="preview" class="preview" />
  }
</div>

@if (message.length) {
<div class="alert alert-secondary my-3" role="alert">
  <ul>
    @for (msg of message; track $index) {
    <li>{{ msg }}</li>
    }
  </ul>
</div>
}

<div class="card mt-3">
  <div class="card-header">List of Images</div>
  <ul class="list-group list-group-flush">
    @for (image of imageInfos | async; track image.name) {
    <li class="list-group-item">
      <p><a href="{{ image.url }}">{{ image.name }}</a></p>
      <img src="{{ image.url }}" alt="{{ image.name }}" height="80px" />
    </li>
    }
  </ul>
</div>

upload-images.component.css

.preview {
  max-width: 165px;
}

ul {
  margin-bottom: 0;
}

.alert {
  padding-left: 0;
}

Add Upload Images Component to App Component

Import UploadImagesComponent in app.component.ts.

import { Component } from '@angular/core';
import { CommonModule } from '@angular/common';
import { RouterOutlet } from '@angular/router';
import { UploadImagesComponent } from './components/upload-images/upload-images.component';

@Component({
  selector: 'app-root',
  standalone: true,
  imports: [CommonModule, RouterOutlet, UploadImagesComponent],
  templateUrl: './app.component.html',
  styleUrl: './app.component.css'
})
export class AppComponent {
  title = 'Angular 17 Multiple Image Upload with Preview';
}

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

<div class="container" style="width:550px">
  <div class="my-3">
    <h3>bezkoder.com</h3>
    <h4>{{ title }}</h4>
  </div>

  <app-upload-images></app-upload-images>
</div>

Run the App

If you use one of following server:
Node.js Express File Upload Rest API example
Node.js Express File Upload to MongoDB example
Node.js Express File Upload to Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

You need run with port 8081 for CORS origin http://localhost:8081 with command:
ng serve --port 8081

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

Or run on Stackblitz:

Further Reading

Using Material: Angular Material 17 Image upload with Preview example

Conclusion

Today we’re learned how to build an example for multiple Images upload with preview using Angular 17 and Bootstrap 4. We also provide the ability to show list of images and display multiple progress bars.

The source code for the Angular 17 Client is uploaded to Github.