Angular Material 12 Image upload with Preview example

In this tutorial, I will show you way to build (Multiple) Image upload and Preview example with Web API/Rest API using Angular Material 12, FormData and Progress Bar.

More Practice:
Angular 12 + Spring Boot: File upload example
Angular 12 + Node.js: File Upload example
Angular 12 Login and Registration example with JWT & Web Api
Angular 12 CRUD Application example with Web API
Angular 12 Form Validation example (Reactive Forms)
– Using Bootstrap: Angular 12 Multiple Images Upload with Preview example

Serverless with Firebase:
Angular 12 Upload File to Firebase Storage example


Overview

We will create an Angular Material 12 (Multiple) Image upload with Preview application in that user can:

  • 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 React App:

– Before upload:

angular-material-12-image-upload-preview-example-before-upload

– When Upload is done:

angular-material-12-image-upload-preview-example

– List of Images Display with download Urls:

angular-material-12-image-upload-preview-example-image-list

– Show status for each image upload:

angular-material-12-image-upload-preview-example-upload-status

Technology

  • Angular 12
  • RxJS 6
  • Angular Material 12

Web API for Image Upload & Storage

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

MethodsUrlsActions
POST/uploadupload a File
GET/filesget 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 Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

Setup Angular Material 12 Image Upload Preview Project

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

ng new AngularMaterial12ImageUploadPreview
? 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/upload-images

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

Angular Material 12 App for Image upload with Preview

angular-12-multiple-image-upload-preview-example-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 Apis Server.
upload-images.component contains upload multiple images form, preview, some progress bars, display list of images.
app.component is the container that we embed all components.
index.html for importing the Font and Icons.

Install Angular Material

Set up your Angular Material project by running the command:
ng add @angular/material

You need to answer some questions:

ℹ Using package manager: npm
✔ Found compatible package version: @angular/[email protected]
✔ Package information loaded.

The package @angular/[email protected] will be installed and executed.
Would you like to proceed? Yes
✔ Package successfully installed.
? Choose a prebuilt theme name, or "custom" for a custom theme:
  Indigo/Pink        [ Preview: https://material.angular.io?theme=indigo-pink ]      
> Deep Purple/Amber  [ Preview: https://material.angular.io?theme=deeppurple-amber ] 
  Pink/Blue Grey     [ Preview: https://material.angular.io?theme=pink-bluegrey ]    
  Purple/Green       [ Preview: https://material.angular.io?theme=purple-green ]     
  Custom
  
? Set up global Angular Material typography styles? Yes 
? Set up browser animations for Angular Material? No

The command will install Angular Material, the Component Dev Kit (CDK), Angular Animations and additionally perform the following configurations:

  • Add project dependencies to package.json
  • Add the Roboto font to index.html
  • Add the Material Design icon font to index.html
  • Add a few global CSS styles to styles.css

Set up App Module

Open app.module.ts, import HttpClientModule and several Angular Material modules:

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

import { AppComponent } from './app.component';
import { NoopAnimationsModule } from '@angular/platform-browser/animations';
import { UploadImagesComponent } from './components/upload-images/upload-images.component';

import { MatCardModule } from '@angular/material/card';
import { MatToolbarModule } from '@angular/material/toolbar';
import { MatButtonModule } from '@angular/material/button';
import { MatInputModule } from '@angular/material/input';
import { MatFormFieldModule } from '@angular/material/form-field';
import { MatProgressBarModule } from '@angular/material/progress-bar';
import { MatListModule } from '@angular/material/list';

const materialModules = [
  MatCardModule,
  MatToolbarModule,
  MatButtonModule,
  MatInputModule,
  MatFormFieldModule,
  MatProgressBarModule,
  MatListModule
];

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

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 Multiple Files Upload Rest server.

Create Angular Material 12 Component for Upload Images

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

First we need to use the following imports:

upload-images.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 UploadImagesComponent implements OnInit {

  selectedFiles?: FileList;
  selectedFileNames: string[] = [];

  progressInfos: any[] = [];
  message: string[] = [];

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

  constructor(private uploadService: FileUploadService) { }
}

The progressInfos is an array that contains items for display upload progress of each images. Each item will have 2 fields: percentage & fileName.

selectedFileNames array will be used for displaying selected files.

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.progressInfos = [];
  this.selectedFileNames = [];
  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) => {
        console.log(e.target.result);
        this.previews.push(e.target.result);
      };

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

      this.selectedFileNames.push(this.selectedFiles[i].name);
    }
  }
}

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(idx: number, file: File): void {
  this.progressInfos[idx] = { value: 0, fileName: file.name };

  if (file) {
    this.uploadService.upload(file).subscribe(
      (event: any) => {
        if (event.type === HttpEventType.UploadProgress) {
          this.progressInfos[idx].value = Math.round(100 * event.loaded / event.total);
        } else if (event instanceof HttpResponse) {
          const msg = 'Uploaded the file successfully: ' + file.name;
          this.message.push(msg);
          this.imageInfos = this.uploadService.getFiles();
        }
      },
      (err: any) => {
        this.progressInfos[idx].value = 0;
        const msg = 'Could not upload the file: ' + file.name;
        this.message.push(msg);
      });
  }
}

We use idx for accessing index of the current File to work with progressInfos array. Then we call uploadService.upload() method on the file.

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 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 Upload Images UI with Angular Material Components.
Add the following content to upload-images.component.html file:

<div *ngFor="let progressInfo of progressInfos">
  <span>{{ progressInfo.fileName }}</span>
  <mat-toolbar class="progress-bar">
    <mat-progress-bar
      color="accent"
      [value]="progressInfo.value"
    ></mat-progress-bar>
    <span class="progress">{{ progressInfo.value }}%</span>
  </mat-toolbar>
</div>

<mat-form-field>
  <div>
    <mat-toolbar>
      <input matInput [value]="selectedFileNames.length ? selectedFileNames : 'Select Images'" />

      <button
        mat-flat-button
        color="primary"
        [disabled]="!selectedFiles"
        (click)="uploadFiles()"
      >
        Upload
      </button>
    </mat-toolbar>

    <input
      type="file"
      id="fileInput"
      name="fileInput"
      accept="image/*" multiple 
      (change)="selectFiles($event)"
    />
  </div>
</mat-form-field>

<div>
  <img *ngFor='let preview of previews' [src]="preview" class="preview">
</div>

<div *ngIf="message.length" class="message">
  <ul *ngFor="let msg of message; let i = index">
    <li>{{ msg }}</li>
  </ul>
</div>

<mat-card class="list-card">
  <mat-card-header>
    <mat-card-title>List of Images</mat-card-title>
  </mat-card-header>
  <mat-card-content>
    <mat-list role="list">
      <mat-list-item role="listitem" *ngFor="let image of imageInfos | async" class="list-item">
        <p matLine><a href="{{ image.url }}">{{ image.name }}</a></p>
        <img src="{{ image.url }}" alt="{{ image.name }}" height="50px"/>
      </mat-list-item>
    </mat-list>
  </mat-card-content>
</mat-card>

Don’t forget to customize the style with CSS in upload-images.component.css:

.progress-bar {
  padding: 0;
}

.progress {
  width: 50px;
}

.mat-input-element {
  font-size: medium;
  font-weight: 200;
}

#fileInput {
  position: absolute;
  cursor: pointer;
  z-index: 10;
  opacity: 0;
  height: 100%;
  left: 0px;
  top: 0px;
}

.mat-toolbar-single-row {
  height: auto !important;
  background: transparent;
  padding: 0;
}

.mat-toolbar-single-row button {
  width: 100px;
}

.mat-form-field {
  width: 100%;
}

.message {
  background-color: #ddd;
  padding: 15px;
  color: #333;
  border: #aaa solid 1px;
  border-radius: 4px;
  margin: 15px 0;
}

.preview {
  max-width: 200px;
  vertical-align: middle;
}

.list-card {
  margin-top: 20px;
}

.list-item {
  margin-bottom: 20px;
}

Add Upload Multiple Images Component to App Component

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

<div class="container">
  <h3>bezkoder.com</h3>
  <h4>{{ title }}</h4>

  <app-upload-images></app-upload-images>
</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 Material 12 Image Upload with Preview';
}

app.component.css

.container {
  width: 600px;
  margin: 20px auto;
}

.container h3{
  font-size: xx-large;
}

.container h4{
  font-size: x-large;
}

Run the App

If you use one of following server:
Node.js Express File Upload Rest API 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 Bootstrap: Angular 12 Multiple Images Upload with Preview example

Conclusion

Today we’re learned how to build an example for (multiple) Image upload with preview using Angular Material 12. We also provide the ability to show list of images and display multiple progress bars.

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 Google Cloud Storage example
Spring Boot Multipart File upload (to static folder) example

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

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