AJAX transfer large amount of data using $_POST method - php

Question

I would like to transfer a large amount of text to the server using AJAX. I would like to attach this text using the POST method, but I get the following error:
request failed: URI too long (longer than 8190)
My javascript code:
function loadXMLDoc(data) {
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
}
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("myDiv").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("POST", "http://www.mydomain.com/test2.php?blob=" + data, true);
xmlhttp.send();
}
My php code:
$dataraw = $_GET["blob"];
file_put_contents('/path/to/my/file/newfile.txt', $dataraw);
echo 'file saved';

Answer 1

You should change this
xmlhttp.open("POST","http://www.mydomain.com/test2.php?blob=" + data,true);
xmlhttp.send();
to this:
xmlhttp.open("POST", "http://www.mydomain.com/test2.php", true);
var payload = "blob=" + data;
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.setRequestHeader("Connection", "close");
xmlhttp.setRequestHeader("Content-length", payload.length);
xmlhttp.send(payload);
In POST, parameters should go in the body of the message, not the URL.
At the same time, you should expect the parameters on the server-side in $_POST - that's where the body parameter will end up in in PHP.

Answer 2

You don't add post-data to the URL. Please check this link to find an example of a post-request:
http://www.w3schools.com/ajax/ajax_xmlhttprequest_send.asp
xmlhttp.open("POST","ajax_test.asp",true);
xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
xmlhttp.send("fname=Henry&lname=Ford");