Program Plan

1. When a user uploads a file for the first time, the system should upload the file in the specified folder and insert the file details like file name, size, and type in the database table.
2. When the user uploads a file for the second time (the filename has to be the same), the system will compare the size, date and time of the existing file and of the file being uploaded, and automatically assign a new version for the uploaded file if there is a difference. If there is no difference, then the existing file will be retained and a message will be displayed for the user.
3. A check box allows the user to replace the existing file. Clicking this option will replace the exiting file. Note that only the latest version of the file can be replaced in this case, and not an older one.
4. The database will maintain file list and version details. Users should be able to view all the versions of a file and download the required version.
5. While displaying the file list, the program displays all the versions of files under one name. For example, if the file name is xyz.doc and its other versions are xyz_VERSION1.doc, xyz_VERSION2.doc, xyz_VERSION3.doc, xyz_VERSION4.doc, xyz_VERSION5.doc and so on. The program will display filename as xyz.doc for all the versions.
6. The program allows users to delete the file. Clicking on delete will ask for confirmation before proceeding.

Building the Database:

Database Name: upload

The database contains one table, ‘file_manager’ that manages file information.

The sql statement for creating the table:

CREATE TABLE file_manager (
file_name varchar(50) default NULL, 
file_type varchar(20) NOT NULL default \'\', 
file_size varchar(20) NOT NULL default \'\', 
file_modified varchar(20) NOT NULL default \'\', 
file_parent_id mediumint(9) default NULL, 
file_image_name varchar(50) default NULL,

KEY file_name (file_name), 
KEY file_image_name (file_image_name)
) TYPE=MyISAM;

File Management:

There are two programs to manage this file version.  The first to upload the file (file_upload_manager.php), the second is to display the file (file_display_manager.php). The source code is tested on a Windows system.

File Upload Manager:

This program displays a menu to select the file in your system, a check box and an Upload button.

Once the user clicks the upload button, the program checks the file for existence, and undergoes a series of tests as described in the plan.

Now let’s look upon the code snippets used in the program.

$dir_path Variable:

This variable is the destination folder path.

$dir_path= "C:apachehtdocsfilemanager";

This path is given for Windows-based systems. Please change your destination folder accordingly.

Get_New_File_Name() Function:

This function is called from the main program when the program encounters file exists and difference in size, date or time. This function will generate a new file name and return to the main function.

function Get_New_FIle_Name($file_name)
{

  $sqlQuery="SELECT  file_image_name FROM file_manager WHERE  file_name LIKE \'$file_name%\' AND  file_parent_id=1";

  $fResult=mysql_query($sqlQuery);
  $Last_Version=0;
  $ver=0;

  if(mysql_num_rows($fResult)){
      while($fRow=mysql_fetch_array($fResult)){
         list($junk,$ver)=explode("_VERSION",$fRow[\'file_image_name\']);
         list($ver,$extn)=explode(".",$ver);
         $Last_Version = $Last_Version > $ver ? $Last_Version : $ver;
       }
  }else{
      $new_file_name =$file_name."_VERSION".++$Last_Version;
      return $new_file_name;
  }

  if($Last_Version !=0){
      $new_file_name=$file_name."_VERSION".++$Last_Version;
      return $new_file_name;
  }
}

The sql query in the beginning of the function will fetch file names of previous versions.

If the sql query returns record sets, it means the file has previous versions. The while loop is executed to store the generated version number, and the value obtained is stored in $Last_Version. Otherwise, the new file name will be generated as file-name_VERSION1.

The next if statement checks for $Last_Version != 0, if true, $Last_Version is incremented by 1 and a new file name is assigned.

The return statement will return a new file name generated to the called statement.

File_Size() Function:

This function returns the file size in terms of Bytes, Kb or Mb.

<?
function File_Size($size)
{
    if($size > 104876){
        return $return_size=sprintf("%01.2f",$size / 104876)." Mb";
    }elseif($size > 1024){
        return $return_size=sprintf("%01.2f",$size / 1024)." Kb";
    }else{
        return $return_size=$size." Bytes";
    }

}
?>

Display_form() Function:

This function is used to prompt the user to select the file from your local machine.

<?
function display_form($errMsg){
    global $dir_path;

?>
<html>
<head><title>File Manager</title></head>
<body bgcolor="#E5E5E5">
<div align="center">
<h4>File Manager</h4>

<? if($errMsg){
?><font face="verdana, helvetica" size="2" color="red"><? echo $errMsg ?></font>
<?
} 
?>
<form action="<? echo $PHP_SELF; ?>"  enctype="multipart/form-data" method="POST">
<table border="1">
<tr><th>File Location:</th><th><input type="file" name="up_file" /></th></tr>
<tr><th colspan="2"><br><input type="checkbox" name="replace" value="1">Replace Exiting File*</th></tr>
<tr><th colspan="2"><br><input type="submit" name="upload" value="Upload File !" /></th></tr>
</table>

<br>* - Clicking this option will replace the existing file
<br><a href="file_display_manager.php">File Manager</a>

<br><? if ($status){ echo "Result  :".$status;  }?>

<p><br><b>Folder Location:</b><? echo $dir_path ?>
<br>You can change this location by editing the file</font>

</form>
</div>
</body>
</html>
<? } ?>

When you execute file_upload_manager.php, the following code is executed first and the other functions described above are called in the middle of the program.

Once the user selects the file and clicks upload, the main program part is executed. Here the program gets the upload file information like file size, file type, date modified and time stamp.

Next it checks for the file existence in the destination folder.  If the file is present the “if” part of the program gets executed, otherwise the file is copied to the destination folder and the file information is inserted in the database.

If the file exists, and if the file size and/or time stamp differs, Get_New_File_Name() function is called to generate a new file name. Then the file is copied to the destination folder and the file information is stored in the database.

If the file exists and the user had checked the “Replace Existing File” option, the file is replaced and the file information is updated in the database accordingly. Otherwise, the user is redirected to the file_display_manager.php page and the message “A previous version of this file exists” is displayed.

File Display Manager:

This PHP script handles the displaying of files present in the folder. As described in the plan, the program will display the file name, size, type and an option to delete the file.

dir_display() Function:

This function displays the files available in the folder in a table. The template looks like this:

You can see that the file names are repeated. But you can see the file size and date modified differs. To view / download the file, you can click the hyperlink of the file name.  This will show you the file name of the different version. You can customize the program to include another field “Version” to track the file version.

To delete a file, click on the ‘Delete’ hyperlink, which will prompt for confirmation.