How to download a pdf using ajax and TCPDF - php

Question

My code works fine when I run the php script without ajax as a GET request. I get prompted to download the rendered pdf and all is well. However, I need to use ajax because I need to send more info from an html page to the php script than can be handled in a GET request.
What do I need to put into my ajax to make this work?
Thanks
js
function makePDF()
{
var x;
if(window.event) // IE8 and earlier
{
x=event.keyCode;
}
else if(event.which) // IE9/Firefox/Chrome/Opera/Safari
{
x=event.which;
}
keychar=String.fromCharCode(x);
alert(keychar);
if (keychar == 'p' || keychar == 'P')
{
var charSheetHTML = characterSheet.innerHTML;
$.ajax({
url: 'pdf.php',
data: {'charactersheet': charSheetHTML,},
type: 'post',
success: function (data) {**WHAT_DO_I_PUT_HERE??**},
error: function (data) { alert("error\n" + data.toString()); }
});
}
}
pdf.php
<?php
include_once( "bxcharacter/PDFChar.php.inc" );
PDFChar();
?>
PDFChar.hph.inc
<?php
require_once('./tcpdf/tcpdf.php');
function PDFChar(){
$pdf = new TCPDF();
$pdf->AddPage('P');
$pdf->writeHTML($_POST['charactersheet']);
$pdf->Output("character.pdf", 'D');
}
?>

Answer 1

This is not an ajax solution, but you can send your data with this way and if no error occurs, your page will not change.
Create a form element with inputs hidden which contains your data you want to send:
example format:
<form id="myForm" method="GET" action="pdf.php">
<input type="hidden" name="data1" type="hidden" value="your JSON.stringify() data">
</form>
js code (call these where your ajax request is):
var myForm = '<form id="myForm" method="GET" action="pdf.php">';
myForm += '<input type="hidden" name="data1" type="hidden" value="JSON.stringify() data">';
myForm += '</form>';
$("body").append(myForm); // temporarily appending
$("#myData-form").submit(); // submitting form with data
$("#myData-form").remove(); // remove form after submit
And as you said, force download will force file to download and page will remain same. However, if an error occurs, your page will change of course.
I don't know whether this is an effective way or not but in my case, this does the trick.

Answer 2

Old question, but I was trying to do something similar with Laravel PDF extension, and stumbled across this question. I did successfully do this asynchronously with the help of a nice blog post
https://nehalist.io/downloading-files-from-post-requests/
https://github.com/nehalist/download-post-requests
The using the form method, like the previous answer works fine too, but maybe this will help anyone else trying to achieve this with AJAX. The author's XMLHttpRequest method worked great for me!
The code that worked for me (almost verbatim from the blog post) ->
document.getElementById('exportpdf').addEventListener('click', function () {
var request = new XMLHttpRequest();
request.open('POST', '/your/post/endpoint/here', true);
request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
request.responseType = 'blob';
request.onload = function() {
if(request.status === 200) {
var disposition = request.getResponseHeader('content-disposition');
var matches = /"([^"]*)"/.exec(disposition);
var filename = (matches != null && matches[1] ? matches[1] : 'file.pdf');
var blob = new Blob([request.response], { type: 'application/pdf' });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = filename;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
}
};
I tried to get it to work with jQuery AJAX but failed, so I went with XMLHttpRequest. With jQuery, The download would work, but the content was always empty. I tried to do something like in this post -
https://keyangxiang.com/2017/09/01/HTML5-XHR-download-binary-content-as-Blob/
$.ajax does not support either arraybuffer or blob as its dataType. Thus we need write a beforeSend handler:
//setup ajax
$.ajaxSetup({
beforeSend:function(jqXHR,settings){
if (settings.dataType === 'binary'){
settings.xhr().responseType='arraybuffer';
settings.processData=false;
}
}
})
//use ajax now
$.ajax({
url:url,
dataType:"binary",
success:function(data){
console.log(data); //ArrayBuffer
console.log(new Blob([data])) // Blob
}
})
But never got it to work. Maybe someone smarter can figure out the jQuery method :)