Lightning File Upload Component

FileController.cls

public class FileController {
    
    @AuraEnabled
    public static Id saveTheFile(Id parentId, String fileName, String base64Data, String contentType) { 
        base64Data = EncodingUtil.urlDecode(base64Data, 'UTF-8');
        
        Attachment a = new Attachment();
        a.parentId = parentId;

        a.Body = EncodingUtil.base64Decode(base64Data);
        a.Name = fileName;
        a.ContentType = contentType;
        
        insert a;
        
        return a.Id;
    }
    
    @AuraEnabled
    public static Id saveTheChunk(Id parentId, String fileName, String base64Data, String contentType, String fileId) { 
        if (fileId == '') {
            fileId = saveTheFile(parentId, fileName, base64Data, contentType);
        } else {
            appendToFile(fileId, base64Data);
        }
        
        return Id.valueOf(fileId);
    }
    
    private static void appendToFile(Id fileId, String base64Data) {
        base64Data = EncodingUtil.urlDecode(base64Data, 'UTF-8');
        
        Attachment a = [
            SELECT Id, Body
            FROM Attachment
            WHERE Id = :fileId
        ];
        
     	String existingBody = EncodingUtil.base64Encode(a.Body);
        a.Body = EncodingUtil.base64Decode(existingBody + base64Data); 
        
        update a;
    }
}

fileUpload.cmp

<!-- fileUpload2.cmp is identical -->
<aura:component controller="paura.FileController">
    <aura:attribute name="parentId" type="Id"/>
    
    <aura:handler event="aura:waiting" action="{!c.waiting}"/>
    <aura:handler event="aura:doneWaiting" action="{!c.doneWaiting}"/>
    
    <div class="container">
        <input type="file" class="file" aura:id="file" />
        <ui:button label="Save" press="{!c.save}"/>
        
        <div aura:id="uploading" class="notUploading">
            <img src="/resource/paura__images/loading-gray.gif" alt="uploading" class="small-spinner" /> Uploading...
    	</div>
    </div>
    
</aura:component>

fileUpload.css

/* fileUpload2.css is identical */
.THIS .notUploading {
    visibility: hidden;
}

.THIS .uploading {
    visibility: visible;
    display: inline-block;
    margin-top: 10px;
}

.THIS .small-spinner {
    height: 20px;
    width: 20px;
}

.THIS .file {
    margin-bottom: 5px;
    display: block;
}

fileUploadController.js

/* fileUploadController2.js is identical */
({  
    save : function(component, event, helper) {
        helper.save(component);
    },
    
    waiting: function(component, event, helper) {
    	$A.util.addClass(component.find("uploading").getElement(), "uploading");
    	$A.util.removeClass(component.find("uploading").getElement(), "notUploading");
    },
    
    doneWaiting: function(component, event, helper) {
    	$A.util.removeClass(component.find("uploading").getElement(), "uploading");
    	$A.util.addClass(component.find("uploading").getElement(), "notUploading");
    }
})

fileUploadHelper.js

({
    MAX_FILE_SIZE: 750 000, /* 1 000 000 * 3/4 to account for base64 */

    save : function(component) {
        var fileInput = component.find("file").getElement();
    	var file = fileInput.files[0];
   
        if (file.size > this.MAX_FILE_SIZE) {
            alert('File size cannot exceed ' + this.MAX_FILE_SIZE + ' bytes.\n' +
    		  'Selected file size: ' + file.size);
    	    return;
        }
    
        var fr = new FileReader();
        
	var self = this;
       	fr.onload = function() {
            var fileContents = fr.result;
    	    var base64Mark = 'base64,';
            var dataStart = fileContents.indexOf(base64Mark) + base64Mark.length;

            fileContents = fileContents.substring(dataStart);
        
    	    self.upload(component, file, fileContents);
        };

        fr.readAsDataURL(file);
    },
        
    upload: function(component, file, fileContents) {
        var action = component.get("c.saveTheFile"); 

        action.setParams({
            parentId: component.get("v.parentId"),
            fileName: file.name,
            base64Data: encodeURIComponent(fileContents), 
            contentType: file.type
        });

        action.setCallback(this, function(a) {
            attachId = a.getReturnValue();
            console.log(attachId);
        });
            
        $A.run(function() {
            $A.enqueueAction(action); 
        });
    }
})

fileUploadHelper2.js

({
    MAX_FILE_SIZE: 4 500 000, /* 6 000 000 * 3/4 to account for base64 */
    CHUNK_SIZE: 950 000, /* Use a multiple of 4 */

    save : function(component) {
        var fileInput = component.find("file").getElement();
    	var file = fileInput.files[0];
   
        if (file.size > this.MAX_FILE_SIZE) {
            alert('File size cannot exceed ' + this.MAX_FILE_SIZE + ' bytes.\n' +
    		  'Selected file size: ' + file.size);
    	    return;
        }
        
        var fr = new FileReader();

	var self = this;
        fr.onload = function() {
            var fileContents = fr.result;
    	    var base64Mark = 'base64,';
            var dataStart = fileContents.indexOf(base64Mark) + base64Mark.length;

            fileContents = fileContents.substring(dataStart);
       
    	    self.upload(component, file, fileContents);
        };

        fr.readAsDataURL(file);
    },
        
    upload: function(component, file, fileContents) {
        var fromPos = 0;
        var toPos = Math.min(fileContents.length, fromPos + this.CHUNK_SIZE);
		
       	// start with the initial chunk
        this.uploadChunk(component, file, fileContents, fromPos, toPos, '');   
    },
     
    uploadChunk : function(component, file, fileContents, fromPos, toPos, attachId) {
        var action = component.get("c.saveTheChunk"); 
        var chunk = fileContents.substring(fromPos, toPos);

        action.setParams({
            parentId: component.get("v.parentId"),
            fileName: file.name,
            base64Data: encodeURIComponent(chunk), 
            contentType: file.type,
            fileId: attachId
        });
       
        var self = this;
        action.setCallback(this, function(a) {
            attachId = a.getReturnValue();
            
            fromPos = toPos;
            toPos = Math.min(fileContents.length, fromPos + self.CHUNK_SIZE);
            
            if (fromPos < toPos) {
            	self.uploadChunk(component, file, fileContents, fromPos, toPos, attachId);  
            }
        });
            
        $A.run(function() {
            $A.enqueueAction(action); 
        });
    }
})

widgets.app

<!-- This is a simple app that shows how the component can be used.
     The Id could be passed in via URL or some other mechanism. 
     This is just for testing.
-->
<aura:application>
    <div class="container">
        <!--<paura:fileUpload parentId="0013020s006DqaI"/>-->
        <paura:fileUpload2 parentId="0013020s006DqaI"/>
    </div>
</aura:application>

Hi @peterknolle @Satya738

How can we modify the code to upload a 10 MB file ?