How to upload base64 image resource with dropzone?

Question

I'm trying to upload generated client side documents (images for the moment) with Dropzone.js.

// .../init.js

var myDropzone = new Dropzone("form.dropzone", {
    autoProcessQueue: true
}); 

Once the client have finished his job, he just have to click a save button which call the save function :

// .../save.js

function save(myDocument) {

    var file = { 
        name: 'Test',
        src: myDocument,
    };

    console.log(myDocument);

    myDropzone.addFile(file);
}

The console.log() correctly return me the content of my document

 data:image/png;base64,iVBORw0KGgoAAAANS...

At this point, we can see the progress bar uploading the document in the drop zone but the upload failed.

Here is my (standart dropzone) HTML form :

<form action="/upload" enctype="multipart/form-data" method="post" class="dropzone">
    <div class="dz-default dz-message"><span>Drop files here to upload</span></div>
    <div class="fallback">
        <input name="file" type="file" />
    </div>
</form>

I got a Symfony2 controller who receive the post request.

// Get request
$request = $this->get('request'); 

// Get files
$files = $request->files;

// Upload
$do = $service->upload($files);

Uploading from the dropzone (by drag and drop or click) is working and the uploads are successfull but using the myDropzone.addFile() function return me an empty object in my controller :

var_dump($files);

return

object(Symfony\Component\HttpFoundation\FileBag)#11 (1) {
  ["parameters":protected]=>
  array(0) {
  }
}

I think i don't setup correctly my var file in the save function. I tryied to create JS image (var img = new Image() ...) but without any success.

Thanks for your help !

Answer 1

Finally i found a working solution without creating canvas :

function dataURItoBlob(dataURI) {
    'use strict'
    var byteString, 
        mimestring 

    if(dataURI.split(',')[0].indexOf('base64') !== -1 ) {
        byteString = atob(dataURI.split(',')[1])
    } else {
        byteString = decodeURI(dataURI.split(',')[1])
    }

    mimestring = dataURI.split(',')[0].split(':')[1].split(';')[0]

    var content = new Array();
    for (var i = 0; i < byteString.length; i++) {
        content[i] = byteString.charCodeAt(i)
    }

    return new Blob([new Uint8Array(content)], {type: mimestring});
}

And the save function :

function save(dataURI) {

    var blob = dataURItoBlob(dataURI);
    myDropzone.addFile(blob);

}

The file appears correctly in dropzone and is successfully uploaded. I still have to work on the filename (my document is named "blob").

The dataURItoBlob function have been found here : Convert Data URI to File then append to FormData

[EDIT] : I finally wrote the function in dropzone to do this job. You can check it here : https://github.com/CasperArGh/dropzone And you can use it like this :

var dataURI = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAmAAAAKwCAYAAA...';
myDropzone.addBlob(dataURI, 'test.png');

Answer 2

I can't comment currently and wanted to send this to you.

I know you found your answer, but I had some trouble using your Git code and reshaped it a little for my needs, but I am about 100% positive this will work for EVERY possible need to add a file or a blob or anything and be able to apply a name to it.

Dropzone.prototype.addFileName = function(file, name) {
    file.name = name;
  file.upload = {
    progress: 0,
    total: file.size,
    bytesSent: 0
  };
  this.files.push(file);
  file.status = Dropzone.ADDED;
  this.emit("addedfile", file);
  this._enqueueThumbnail(file);
  return this.accept(file, (function(_this) {
    return function(error) {
      if (error) {
        file.accepted = false;
        _this._errorProcessing([file], error);
      } else {
        file.accepted = true;
        if (_this.options.autoQueue) {
          _this.enqueueFile(file);
        }
      }
      return _this._updateMaxFilesReachedClass();
    };
  })(this));
};

If this is added to dropzone.js (I did just below the line with Dropzone.prototype.addFile = function(file) { potentially line 1110.

Works like a charm and used just the same as any other. myDropzone.addFileName(file,name)!

Hopefully someone finds this useful and doesn't need to recreate it!

Answer 3

1) You say that: "Once the client have finished his job, he just have to click a save button which call the save function:"

This implies that you set autoProcessQueue: false and intercept the button click, to execute the saveFile() function.

$("#submitButton").click(function(e) {
    // let the event not bubble up
    e.preventDefault();
    e.stopPropagation();
    // process the uploads
    myDropzone.processQueue();
});

2) check form action

Check that your form action="/upload" is routed correctly to your SF controller & action.

3) Example Code

You may find a full example over at the official Wiki

4) Ok, thanks to your comments, i understood the question better:

"How can i save my base64 image resource with dropzone?"

You need to embedd the image content as value

// base64 data
var dataURL = canvas.toDataURL();

// insert the data into the form
document.getElementById('image').value = canvas.toDataURL('image/png');
//or jQ: $('#img').val(canvas.toDataURL("image/png"));

// trigger submit of the form
document.forms["form1"].submit();

• You might run into trouble doing this and might need to set the "origin-clean" flag to "true". see http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#security-with-canvas-elements
• how to save html5 canvas to server