Getting DOMPDF working inside CakePHP 1.2

One of my current projects at Futurate is the development of a sophisticated database for JISC, which is being developed using the excellent CakePHP framework (I'm also extensively using the jQuery library in order to enhance the user experience).

I can spend all day heaping praise on CakePHP, but that won't tell you how to get DOMPDF (a 3rd party PHP library that creates PDF documents from HTML source) working inside the CakePHP framework will it?

So here's how I did it:

Download DOMPDF and extract the library into your /app/vendors/ directory.

Now comes the bit that took me two days to work out...

Your action in your controller should look something like this:

function action() {

 $html = /* your code to generate the HTML you want to turn into a PDF
  
 // turn off debugging output as this interferes with the PDF
 Configure::write('debug', '0');
 ini_set("display_errors", 0);
  
 // create the pdf
 $dompdf = new DOMPDF();
 $dompdf->load_html($html);
 $dompdf->render();
  
 $dompdf->stream("sample.pdf");

The important bit is switching off the errors (marked in bold red). Usually this is a *Bad Thing^(TM)* but in this case it's critical.

You see, CakePHP squirts out debugging information into the output stream (usually your HTML) and it looks like DOMPDF has some warning error messages that also get squirted into the stream too.

This is the LAST thing you want while you are in the middle of streaming out a PDF document. It renders the finished PDF invalid and unreadable.

I finally cracked this nasty nut by trawling through the generated (and corrupt) PDF document until I spotted some PHP error messages and then a little later, CakePHP's debug info.