AEM Cloud Service - Validate asset file extensions while uploading to AEM in browser

Goal

The following steps explain adding a client side script to validate the file types while uploading to AEM using browser..

Demo | Package Install | Github

Solution

1) Create a project eaem-cs-validate-assets using archetype - https://github.com/adobe/aem-project-archetype

mvn -B archetype:generate -D archetypeGroupId=com.adobe.aem -D archetypeArtifactId=aem-project-archetype 
-D archetypeVersion=24 -D aemVersion=cloud -D appTitle="Experience AEM Validate Assets on Upload"
-D appId="eaem-cs-validate-assets" -D groupId="apps.experienceaem.assets" -D frontendModule=none  
-D includeExamples=n -D includeDispatcherConfig=n

2) Create node /apps/eaem-cs-validate-assets/clientlibs/supported-file-types of type cq:ClientLibraryFolder, add String[] property categories with value [dam.gui.coral.fileupload], String[] property dependencies with value eaem.lodash.

3) Create file (nt:file) /apps/eaem-cs-validate-assets/clientlibs/supported-file-types/js.txt, add

                        supported-file-types.js

4) Create file (nt:file) /apps/eaem-cs-validate-assets/clientlibs/supported-file-types/supported-file-types.js, add the following code

(function ($, $document) {
"use strict";

    var _ = window._,
        ERROR_MSG = "Unsupported file extensions : ";

    var _origConfirmUpload = window.DamFileUpload.prototype._confirmUpload;

    window.DamFileUpload.prototype._confirmUpload = function (event) {
        var invalidFileNames = [],
            FILE_EXTS_SUPPORTED = getSuppportedFileExtensions();

        this.fileUpload.uploadQueue.forEach(function(item) {
            var fileName = item.name;

            if(!fileName.includes(".")){
                invalidFileNames.push(fileName);
                return;
            }

            var ext = fileName.substring(fileName.lastIndexOf(".") + 1);

            if(!FILE_EXTS_SUPPORTED.includes(ext.toUpperCase())){
                invalidFileNames.push(fileName);
            }
        });

        if(_.isEmpty(invalidFileNames)){
            _origConfirmUpload.call(this, event);

            var uploadDialog = this.uploadDialog;

            _.defer(function(){
                $(uploadDialog).find("input").attr("disabled", "disabled");
            },0)
        }else{
            showAlert(ERROR_MSG + "<b>" + invalidFileNames.join(",") + "</b>");
        }
    };

    function showAlert(message, title, callback){
        var fui = $(window).adaptTo("foundation-ui"),
            options = [{
                id: "ok",
                text: "OK",
                primary: true
            }];

        message = message || "Unknown Error";
        title = title || "Error";

        fui.prompt(title, message, "warning", options, callback);
    }

    function getSuppportedFileExtensions(){
        return [
"JPG", "PNG"
        ];
    }
}(jQuery, jQuery(document)));

5) More supported file extensions can be added by modifying #55 function getSuppportedFileExtensions()