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.
Contents
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 folder.
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 folder
$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 folder
$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
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.
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 🙂
Awesome tutorial! Thanks for your help.
hello what if i have file type of DOCX,DOC type does it shows ?? Thumbnail of that file
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.
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
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?
You know because it doesnt show me the file? It only show me the name of file in a square.
Thnks.
Great tutorial, helped me a lot!