Open PDF using JavaScript AJAX calling PHP backend

Question

I have a method, which calls the backend through AJAX, to get a blob file from MySQL database, which is retrieved by PHP.

The problem is that the PHP variables contain a string, but the AJAX call comes out empty and the PDF function does not work.

Here is the AJAX code, which is getting called.

self.showPDF = function() {
    $.ajax({
            type: 'GET',
            url: BASEURL + 'index.php/myprofile/openUserPDF/' + auth,
            contentType: 'application/json; charset=utf-8',
            dataType: 'json',
        })
        .done(function(data) {
            console.log(data);
            window.open("data:application/pdf," + escape(data));
        })
        .fail(function(jqXHR, textStatus, errorThrown) {
            alert("Could not open pdf" + errorThrown);
        })
        .always(function(data) {});
}

This is the PHP function in the backend, I am using the CodeIgniter framework.

public function openUserPDF($token) {
    if ($this->input->is_ajax_request()) {
        $userid = $this->myajax->getUserByAuth($token);
        if ($userid) {
            /* If we have an impersonated user in the session, let's use him/her. */
            if (isset($_SESSION['userImpersonated'])) {
                if ($_SESSION['userImpersonated'] > 0) {
                    $userid = $_SESSION['userImpersonated'];
                }
            }
            /* now we get the pdf of the user */
            $this->load->model('user_profile');
            $images = $this->user_profile->getUserImageForPDF($userid);
            $pdfString = $images[0]->image;
            $this->output->set_content_type('application/json');
            return $this->output->set_output(json_encode($pdfString));
        } else {
            return $this->output->set_status_header('401', 'Could not identify the user!');
        }
    } else {
        return $this->output->set_status_header('400', 'Request not understood as an Ajax request!');
    }
}

I do retrieve the blob as a string, but that's basically it, it doesn't return back to the AJAX call.

Answer 1

It's a really, really, really, really, really bad idea to load the potentially huge contents of a PDF into memory when you could simply use file_get_contents or readfile to output it directly.

Javascript

self.showPDF = function() {
    window.open(BASE_URL + '/index.php/myprofile/openUserPDF/' + auth);
}

PHP Function

//... validation and querying ...

header('Content-type: application/pdf');
header('Content-Disposition: inline; filename="' . $filename . '"');
header('Content-Transfer-Encoding: binary');
header('Content-Length: ' . filesize($file));
header('Accept-Ranges: bytes');

readfile($pdfString);

(headers from How to render pdf file by using php; see for more information on rendering PDF files using PHP)