How to Display existing files on Server in Dropzone – PHP

Dropzone library makes it easier to implement file upload using drag and drop on the page.

After file uploading, it shows the preview of the file in the upload area.

All the thumbnails are removed when the webpage is getting refreshed.

To recreate the thumbnails after page refresh needs to send AJAX request to get all files list for adding thumbnails while initializing Dropzone.

In this tutorial, I show how you can display existing files stored on the server in the Dropzone file area with jQuery AJAX.

How to Display existing files on Server in Dropzone - PHP


Contents

  1. Download & Include
  2. HTML
  3. CSS
  4. PHP
  5. Script
  6. Demo
  7. Conclusion

1. Download & Include

Download Dropzone library from here and include in <head > section with the jQuery library.

<!-- jQuery -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

<!-- Dropzone CSS and JS -->
<link href='https://cdnjs.cloudflare.com/ajax/libs/dropzone/5.4.0/dropzone.css' type='text/css' rel='stylesheet'>
<script src='https://cdnjs.cloudflare.com/ajax/libs/dropzone/5.4.0/dropzone.js' type='text/javascript'></script>

2. HTML

Create a <form action="upload.php" class="dropzone" > for Dropzone container.

Completed Code

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<link href="dropzone.min.css" rel="stylesheet" type="text/css">
<script src="dropzone.min.js" type="text/javascript"></script>

<div class="container" >
  <div class='content'>
    <form action="upload.php" class="dropzone" >  
    </form> 
  </div> 
</div>

3. CSS

.container{
  margin: 0 auto; 
  width: 50%;
}

.content{
  padding: 5px; 
  margin: 0 auto;
}
.content span{
  width: 250px;
}

.dz-message{
  text-align: center;
  font-size: 28px;
}

.dz-preview .dz-image img{
  width: 100% !important;
  height: 100% !important;
  object-fit: cover;
}

4. PHP

Create a new upload.php file and upload folder to store files.

If $request == 1 then store file to upload directory.

If $request == 2 then read files from upload folder and initialize $file_list Array with name, file size, and path. Return JSON response.

Completed Code

<?php
// Upload directory
$target_dir = "upload/";

$request = 1;
if(isset($_POST['request'])){
  $request = $_POST['request'];
}

// Upload file
if($request == 1){
  $target_file = $target_dir . basename($_FILES["file"]["name"]);

  $msg = "";
  if (move_uploaded_file($_FILES["file"]["tmp_name"], $target_dir.$_FILES['file']['name'])) {
    $msg = "Successfully uploaded";
  }else{ 
    $msg = "Error while uploading";
  }
  echo $msg;
  exit;
}

// Read files from 
if($request == 2){
  $file_list = array();

  // Target directory
  $dir = $target_dir;
  if (is_dir($dir)){

    if ($dh = opendir($dir)){

      // Read files
      while (($file = readdir($dh)) !== false){

        if($file != '' && $file != '.' && $file != '..'){

          // File path
          $file_path = $target_dir.$file;

          // Check its not folder
          if(!is_dir($file_path)){

             $size = filesize($file_path);

             $file_list[] = array('name'=>$file,'size'=>$size,'path'=>$file_path);

          }
        }

      }
      closedir($dh);
    }
  }

  echo json_encode($file_list);
  exit;
}

5. Script

Set Dropzone autoDiscover to false and initialize dropzone on class="dropzone".

Send AJAX POST request from init function to get all the files list. On successfully callback loop on the response and assign { name: value.name, size: value.size } in mockFile.

Use Dropzone addedfile and thumbnail functions to add the existing file to the upload area. With complete function remove the progress bar.

Completed Code

Dropzone.autoDiscover = false;
$(".dropzone").dropzone({
  init: function() { 
    myDropzone = this;
    $.ajax({
      url: 'upload.php',
      type: 'post',
      data: {request: 2},
      dataType: 'json',
      success: function(response){

        $.each(response, function(key,value) {
          var mockFile = { name: value.name, size: value.size };

          myDropzone.emit("addedfile", mockFile);
          myDropzone.emit("thumbnail", mockFile, value.path);
          myDropzone.emit("complete", mockFile);

        });

      }
    });
  }
});

6. Demo

View Demo


7. Conclusion

In the example, I read all files of the folder and display them in the Dropzone upload area. If you stored the files in the MySQL database then read it and initialize the file name, size, and path in the Array and return it from the AJAX file.

If you found this tutorial helpful then don't forget to share.
Are you want to get implementation help, or modify or extend the functionality of this script? Submit paid service request.

14 thoughts on “How to Display existing files on Server in Dropzone – PHP”

  1. Thank you Yogesh, this is exactly what I was looking for.
    Tried to just show specific filed in pure PHP, but it seems that dz needs mockfiles to work properly – however you did not set acccepted:true in the mockfile array, which seems to be important for updating the maxfile counter? Anyway I will work it out and see for myself 🙂

    Reply
  2. I need to post this images back to the server as files, but i can’t find the way to do that. If i submit your form i receive empty array. I think i need to configure myDropzone.files somehow but i dont know how.

    Reply
  3. Good tutorial.

    Can you help me in creating the link to download the listed files (uploded or fetched already existing files) to the user’s local machine?

    thanks

    Reply
  4. Dear Sir/Madam,

    Very nice tutorial? Is it possible to add a hyperlink to the image so that I can view the image in full size or download it?

    Reply
    • Hi Kelvin,
      You can add download link by adding the following code in AJAX success function in $.each after myDropzone.emit(“complete”, mockFile); –

      // Download link
      var a = document.createElement('a');
      a.setAttribute('href',"/demo/existingfile_dropzone/" + value.path);
      a.innerHTML = "<br>download";
      mockFile.previewTemplate.appendChild(a);
      Reply

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