Using the File Functions in CakePHP

By David Golding

In CakePHP, a very useful set of functions is included but which get little documentation. I had combed the web looking for something useful about how to use the Cake File functions but got little concise or tutorial-based help. After working with the File functions for a little bit now, I figured an explanation might be useful.

Add.ctp View File

Let’s do a simple file upload. Let’s assume that I’m creating blog posts (sorry if using blogs as examples is overkill, but overall I think everyone gets it). For each blog post entry I’d like to upload an image file to match it. In the views/posts/add.ctp file, I have the following basic code:

<h1>Add Post</h1>
<?=$form->create('Post',array('type'=>'file'));?>
<?=$form->input('date',array('label'=>'Publication Date '));?>
<?=$form->input('headline');?>
<?=$form->input('content');?>
<?=$form->input('image',array('type'=>'file'));?>
<?=$form->end('Submit');?>

In the Controller

Now, the most basic upload using the File functions is going to occur in the controllers/posts_controller.php file.

Everything should run like a normal Add function, except I need to actually do the upload of the file.

if ($this->data['Post']['image']) {

$file = new File($this->data['Post']['image']);
$ext = $file->ext();

if ($ext != 'jpg' && $ext != 'jpeg' && $ext != 'gif' && $ext != 'png') {
$this->Session->setFlash('You may only upload image files.');
$this->render();
} else {
$date = $this->data['Post']['date'];
$filename = $date['year'].'-'.$date['month'].'-'.$date['day'].'-post-image.'.$ext;

$data = $file->read();
$file->close();

$file = new File(WWW_ROOT.'/img/'.$filename,true);
$file->write($data);
$file->close();
}
}

Let me explain what is happening here. When the user chooses a file to be uploaded in the HTML form, the link to that file is set through the $_POST variables, and in Cake, as will all form posts, these get parsed into the $this->data array.

The first step, then, is to create a new instance of the File class so we can use those functions.

$file = new File($this->data['Post']['image']);

From here on out, I can pull all sorts of information about this file by using the available Cake functions. You’ll notice that I pulled out the file extension quite easily by using the File->ext() function:

$ext = $file->ext();

If I were to use an echo command in PHP, I would get

jpg

for a JPG file upload.

To write the contents of this file to the server, I need to first fetch all the data in the file.

$data = $file->read();

Now all the contents of the file are held in the $data variable. To write this to the server, I’ll need to create a new file instance, create the file in the appropriate directory (in this case, the webroot/img folder), and dump the contents of $data into that file.

$file->close(); //close out of the user's file

$file = new File(WWW_ROOT.'/img'.$filename,true);

Notice that in creating the new instance for the File class, I’ve used the Cake global variable, WWW_ROOT and I’ve appended the /img directory plus the desired filename. Also, I’ve set create new file to true.

Now the $file variable is set to the new object, which in this case is the empty file on my server stored in the webroot/img directory named whatever is in $filename. By using the write() function, I can plop $data into that file:

$file->write($data);

The rest of the script is just closing out everything.

Other Functions

So how about it? Much, much easier than doing all the classic fopen and fread, fputs functions in PHP. Of course you can branch out and do more as well as error checking using other parameters in the functions themselves.

The CakePHP API contains a list of the available File and Folder functions. By using them like you’ve seen me do above, you can spare yourself superfluous coding.

For example, if I wanted to test if the file by that filename already exists on the server, I can enter:

$id = intval(rand());
$filename = $id.'-post.'.$file->ext();
$folder = new Folder(WWW_ROOT.'/img');
while ($folder->find($filename) == $filename) {
$id++;
$filename = $id.'-post.'.$file->ext();
}

Or if I wanted to delete a file on the server where $file has been set as the class object of the file to be deleted:

$file->delete();

So explore the other File functions and enjoy!

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