PHP: Uploading File with PHP ~ Tech Blog

Thursday, 4 September 2014

PHP: Uploading File with PHP

A PHP script can be used with a HTML form to allow users to upload files to the server. Initially files are uploaded into a temporary directory and then relocated to a target destination by a PHP script.
Information in the phpinfo.php page describes the temporary directory that is used for file uploads as upload_tmp_dir and the maximum permitted size of files that can be uploaded is stated as upload_max_filesize. These parameters are set into PHP configuration file php.ini
The process of uploading a file follows these steps

The user opens the page containing a HTML form featuring a text files, a browse button and a submit button.
The user clicks the browse button and selects a file to upload from the local PC.
The full path to the selected file appears in the text filed then the user clicks the submit button.
The selected file is sent to the temporary directory on the server.
The PHP script that was specified as the form handler in the form's action attribute checks that the file has arrived and then copies the file into an intended directory.
The PHP script confirms the success to the user.

As usual when writing files it is necessary for both temporary and final locations to have permissions set that enable file writing. If either is set to be read-only then process will fail.
An uploaded file could be a text file or image file or any document.

Creating an upload form:

The following HTM code below creates an uploader form. This form is having method attribute set to post and enctype attribute is set to multipart/form-data

<html>
<head>
<title>File Uploading Form</title>
</head>
<body>
<h3>File Upload:</h3>
Select a file to upload: <br />
<form action="/php/file_uploader.php" method="post"
                        enctype="multipart/form-data">
<input type="file" name="file" size="50" />
<br />
<input type="submit" value="Upload File" />
</form>
</body>
</html>

This will display following result:

File Upload:
Select a file to upload: 







NOTE: This is just dummy form and would not work.

Creating an upload script:

There is one global PHP variable called $_FILES. This variable is an associate double dimension array and keeps all the information related to uploaded file. So if the value assigned to the input's name attribute in uploading form was file, then PHP would create following five variables:

$_FILES['file']['tmp_name']- the uploaded file in the temporary directory on the web server.
$_FILES['file']['name'] - the actual name of the uploaded file.
$_FILES['file']['size'] - the size in bytes of the uploaded file.
$_FILES['file']['type'] - the MIME type of the uploaded file.
$_FILES['file']['error'] - the error code associated with this file upload.

The following example below attempts to copy a file uploaded by the HTML Form listed in previous section page to /var/www/html directory which is document root of your PHP server and it will display all the file's detail upon completion. Please note that if you are going to display uploaded file then don't try with binary files like images or word document.
Here is the code of uploader.php script which will take care of uploading a file.

<?php
if( $_FILES['file']['name'] != "" )
{
   copy( $_FILES['file']['name'], "/var/www/html" ) or 
           die( "Could not copy file!");
}
else
{
    die("No file specified!");
}
?>
<html>
<head>
<title>Uploading Complete</title>
</head>
<body>
<h2>Uploaded File Info:</h2>
<ul>
<li>Sent file: <?php echo $_FILES['file']['name'];  ?>
<li>File size: <?php echo $_FILES['file']['size'];  ?> bytes
<li>File type: <?php echo $_FILES['file']['type'];  ?>
</ul>
</body>
</html>

When you will upload a file using upload form and upload script, it will display following result:

Uploaded File Info:

Sent file: uploadedfile.txt
File size: 2003 bytes
File type: image/jpg

Tech Blog

Thursday, 4 September 2014