Determine whether uploader has file input in Angular Uploader component

27 Apr 20247 minutes to read

By setting required attribute to uploader input element, you can validate the file input has any value in it.
In the below sample, set required attribute to the uploader input element and showcase the validation failure message using data-required-message attribute.

app.component.ts

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms'
import { UploaderModule } from '@syncfusion/ej2-angular-inputs'
import { DialogModule } from '@syncfusion/ej2-angular-popups'



import { Component, ViewChild, AfterViewInit } from '@angular/core';
import { EmitType, createElement, detach } from '@syncfusion/ej2-base';
import { UploaderComponent, SelectedEventArgs, FormValidator, FormValidatorModel  } from '@syncfusion/ej2-angular-inputs';
import { DialogComponent } from '@syncfusion/ej2-angular-popups';
@Component({
imports: [
        FormsModule, UploaderModule, DialogModule
    ],


standalone: true,
    selector: 'app-root',
    templateUrl: './default.html',
    styleUrls: ['./index.css']
})

export class AppComponent {
    @ViewChild('defaultupload')
    public uploadObj?: UploaderComponent;
    @ViewChild('dialog')
    public dialog?: DialogComponent;

    public path: Object = {
        saveUrl: 'https://services.syncfusion.com/angular/production/api/FileUploader/Save',
        removeUrl: 'https://services.syncfusion.com/angular/production/api/FileUploader/Remove'
    };
    public removeFile: any = [];
    public content: string = 'Your details have been updated successfully, Thank you.';
    public width: string = '250px';
    public visible: boolean = false;
    public header: string = 'Success';
    public target: HTMLElement = document.getElementById('control_wrapper') as HTMLElement;
    public onFileSelect: EmitType<SelectedEventArgs> = (args: any) =>  {
        if (args.filesData.length > 0) {
        if (document.getElementsByClassName('upload-image').length > 0) {
            detach(document.getElementsByClassName('imgWrapper')[0]);
        }
        let imageTag = createElement('IMG', { className: 'upload-image', attrs: { 'alt': 'Image' } });
        let wrapper: HTMLElement = createElement('span', { className: 'imgWrapper' }) as HTMLElement;
        wrapper.appendChild(imageTag);
        let rootFile = document.getElementsByClassName('dropUpload')[0];
        rootFile.insertBefore(wrapper, rootFile.firstChild);
        this.readURL(wrapper, args.filesData[0]);
        }
        args.cancel = true;
    }
    options: FormValidatorModel | undefined;
    autoUpload: any;
    extensions: any;
    dropElement: any;
    ngAfterViewInit() {
        (document.getElementById('customBrowse') as HTMLElement).onclick = () => {
            (document.getElementsByClassName('e-file-select-wrap')[0].querySelector('button') as HTMLButtonElement).click();
        };
        (document.getElementById('submit-btn') as HTMLElement).onclick = () => {
            this.onFormSubmit();
        };
        let options = { rules: { 'name': { required: true } } };
        let formObj: FormValidator = new FormValidator('#form1', this.options);
        let proxy = this;
        setTimeout(() => {
            this.uploadObj?.element.setAttribute('data-required-message', '* Choose your image to upload');
            this.uploadObj?.element.setAttribute('required', '');
            this.uploadObj?.element.setAttribute('data-msg-containerid', 'uploadError');
        }, 500);
    }
    public readURL: EmitType<SelectedEventArgs> = (li: HTMLElement, args: any) => {
        let preview: HTMLImageElement = li.querySelector('.upload-image') as HTMLImageElement;
        let file: File = args.rawFile; let reader: FileReader = new FileReader();
        reader.addEventListener('load', () => { preview.src = reader.result as string; }, false);
        if (file) { reader.readAsDataURL(file); }
    }
    public onFormSubmit: any = () => {
        let formObj: FormValidator = new FormValidator('#form1', this.options);
        let formStatus: Boolean = formObj.validate();
        if (formStatus) {
            formObj.element.reset();
            detach(document.getElementsByClassName('imgWrapper')[0]);
            this.dialog?.show();
        }
    }
}

main.ts

import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

You can also explore Angular File Upload feature tour page for its groundbreaking features. You can also explore our Angular File Upload example to understand how to browse the files which you want to upload to the server.