How to integrate Dropzonejs with wordpress media handler in frontend?

3 comments

1. Dropzonejs is a very extensive javascript library that provides a lot of options to handle media uploading.

   To integrate dropzonejs with wordpress the process is pretty straight forward. Assume the following piece of code is where you want to appear your uploader.

   <div id="media-uploader" class="dropzone"></div>
   <input type="hidden" name="media-ids" value="">
   

   Having a class dropzone will automatically attach the dropzone event with the element. That will stop us from overriding default parameters. So we would like to disable the auto discover feature of the library.

   // Disabling autoDiscover, otherwise Dropzone will try to attach twice.
   Dropzone.autoDiscover = false;
   

   Now we will use jQuery to bind our configuration with the element.

   jQuery("#media-uploader").dropzone({
       url: dropParam.upload,
       acceptedFiles: 'image/*',
       success: function (file, response) {
           file.previewElement.classList.add("dz-success");
           file['attachment_id'] = response; // push the id for future reference
           var ids = jQuery('#media-ids').val() + ',' + response;
           jQuery('#media-ids').val(ids);
       },
       error: function (file, response) {
           file.previewElement.classList.add("dz-error");
       },
       // update the following section is for removing image from library
       addRemoveLinks: true,
       removedfile: function(file) {
           var attachment_id = file.attachment_id;        
           jQuery.ajax({
               type: 'POST',
               url: dropParam.delete,
               data: {
                   media_id : attachment_id
               }
           });
           var _ref;
           return (_ref = file.previewElement) != null ? _ref.parentNode.removeChild(file.previewElement) : void 0;        
       }
   });
   

   In the code above what we have done is we attached dropzone with our element with some parameters-

   • url – location where we want to send our files to upload. I’ll initialize the variable later.
   • acceptedFiles – since we are only interested in uploading images, we will limit the files to be attached only to images. You can find about more in the website of this library.
   • success – a callback that is fired when the file/image is uploaded successfully. It accepts two parameter the reference of the uploaded file itself and the response from the server. This is very important, here we stored the attachment id in our form. You can perform a validation here prior to store the id.
   • error – if the file failed to upload then you can perform any task here.
   • addRemoveLinks – add the remove file link below the preview panel, you can style it with your css.
   • removedfile – handles the operation while you click on the remove file link for an image in the preview panel. In this function we sent an ajax call to our server to remove the image from the library

   Of course there are a lot of option available, but I found these are the most basic parameters I required to setup my drag-n-drop media uploader.

   Now the most important thing is to decide about the file uploader url. You can have a custom file where you would want to process the operation. But I found another way.

   From this question and the answer I found using admin-post.php file is pretty amazing.

   Many people complained about this admin-post.php, so think sticking to the wp_ajax.php is the best option.

   So I initialized the drophandler variable prior to my dropzone initialization as follows-

   wp_enqueue_script('dropzone','path/to/dropzone', array('jquery'));
   wp_enqueue_script('my-script','path/to/script',array('jquery','dropzone'));
   $drop_param = array(
     'upload'=>admin_url( 'admin-ajax.php?action=handle_dropped_media' ),
     'delete'=>admin_url( 'admin-ajax.php?action=handle_deleted_media' ),
   )
   wp_localize_script('my-script','dropParam', $drop_param);
   

   Now we are ready to send our images to the server. Here we will add some php code whether in the theme’s function.php file or in our plugin file, but we need to be assured that it is loaded.

   The following function will take care of the uploading the image and saving as an attachment in the library.

   add_action( 'wp_ajax_handle_dropped_media', 'handle_dropped_media' );
   
   // if you want to allow your visitors of your website to upload files, be cautious.
   add_action( 'wp_ajax_nopriv_handle_dropped_media', 'handle_dropped_media' );
   
   
   
   function handle_dropped_media() {
       status_header(200);
   
       $upload_dir = wp_upload_dir();
       $upload_path = $upload_dir['path'] . DIRECTORY_SEPARATOR;
       $num_files = count($_FILES['file']['tmp_name']);
   
       $newupload = 0;
   
       if ( !empty($_FILES) ) {
           $files = $_FILES;
           foreach($files as $file) {
               $newfile = array (
                       'name' => $file['name'],
                       'type' => $file['type'],
                       'tmp_name' => $file['tmp_name'],
                       'error' => $file['error'],
                       'size' => $file['size']
               );
   
               $_FILES = array('upload'=>$newfile);
               foreach($_FILES as $file => $array) {
                   $newupload = media_handle_upload( $file, 0 );
               }
           }
       }
   
       echo $newupload;    
       die();
   }
   

   The following action take care of the deletion of the media element. Second parameter of wp_delete_attachment() function allows us to decide whether we want to trash the image or completely delete it. I wanted to delete it completely so passed true.

   add_action( 'wp_ajax_handle_deleted_media', 'handle_deleted_media' );
   
   function handle_deleted_media(){
   
       if( isset($_REQUEST['media_id']) ){
           $post_id = absint( $_REQUEST['media_id'] );
   
           $status = wp_delete_attachment($post_id, true);
   
           if( $status )
               echo json_encode(array('status' => 'OK'));
           else
               echo json_encode(array('status' => 'FAILED'));
       }
   
       die();
   }
   

   This will return the attachment_id in the response and we’ll get it in the success function. In the media_handle_upload( $file, 0 ); I passed the reference of the file and a 0 because I didn’t wanted to assign the media with any post yet (0 for no post, but if you want to assign then pass the post ID here. More reference in the codex.)

   This is all for uploading media in wordpress.

   Note: I haven’t completed the removing uploaded file part. I’ll complete this in a moment.

   UPDATE

   The post is updated. Now we can remove uploaded media elements from the uploader container. Thanks to this question and the answer I could figure out the actual process.

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2. Those who are having problems getting this to work for non-admin users; please use admin-ajax.php instead of admin-post.php.

   I had faced a strange issue that admin-post.php would work for non-admin users on my local server; but my live server refused to let non-admins upload files. php would echo entire page instead of the echoed value.

   I replaced admin-post.php with admin-ajax.php and uploads work super cool.

   I hope this helps.

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3. The solution added to this post is incorrect unless I’ve misunderstood the question. Basically the solution won’t work for anyone who isn’t logged in as an admin. It took me 30 minutes to work it out plus the solution for removing images doesn’t delete it from the media library.

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