PHP/Apache/AJAX - POST limit? - php

Question

I'm trying to send POST data that is 2 million characters big (non-binary string) via ajax (jQuery) and it always comes up as blank on the PHP side. Here is my code:
var string = "<data string that is 2M chars long>";
$.ajax({
cache: false,
type: 'POST',
url: 'data.php',
data: {'data_string': string}
});
On the PHP side, I get the following error message (when trying to retrieve data from $_POST['data_string']):
Notice: Undefined index: data_string in data.php on line ...
I've checked the post_max_size in php.ini, and it's set at 256M which should be more than enough? I'm stumped and not sure what I'm doing wrong...
EDIT: If I make "string" a small amount of data (e.g. var string = 'test') then $_POST["data_string"] returns test, as expected. So I'm wondering if there's some sort of data limit I'm reaching in Apache2, PHP or the browser itself? I'm using Google Chrome 17.0.963.79
EDIT2: memory_limit = 256M in php.ini
EDIT3: max_input_time = -1 in php.ini
EDIT4: var_dump($_POST) returns Array(0)
EDIT5: running the latest stable version of PHP5 on debian squeeze: PHP 5.3.3-7+squeeze8 with Suhosin-Patch (cli) (built: Feb 10 2012 14:12:26)

Answer 1

You'll have to check the limits parameters on all items between you and the server. Quite hard for proxy servers if any, but at least you can check:
Apache:
LimitRequestBody, around 2Gb by default, maybe greater for 64bits, check error logs for details.
PHP:
post_max_size which is directly related to the POST size
upload_max_filesize which may be unrelated, not sure
max_input_time, if the POSt takes too long
max_input_nesting_level if your data is an array with a lot of sublevels
max_execution_time, but quite sure it's not that
memory_limit, as you may reach a size exceding the subprocess allowed memory
max_input_vars, if your data array has many elements
If you have reached the compiled in limit for Apache your only solution is to avoid direct POSt of such a big chunk of data, you'll have to break it into pieces.

Answer 2

You may also check the suhosin.ini settings, eg.:
suhosin.post.max_value_length = 65000

Answer 3

You may also want to set set_time_limit(0) and your memory limit.
EDIT: You may also want to console.log(string); or console.log(string.length); before your request to verify it's being set properly, and also check your request in firebug or chromes developer tools to verify your data is being sent.

Answer 4

//Adding Respond Box After Selected Field
$( '[maxlength]' ).bind('click keyup', function(){
var RespondBox = '<div class="StPgRp" id="UpdateRespond"></div>';
$('#UpdateRespond').remove();
$(this).after(RespondBox);
});
//Counting Maximum Characters Allowed In Selected Field
$( '[maxlength]' ).bind('click keyup', function(){
var MaxLength = $(this).attr('maxlength');
var CurrentLength = $(this).val().length;
var Remainder = MaxLength - CurrentLength;
$('#UpdateRespond').html('You have ' + Remainder + ' characters remaining.');
});
//Checking the PHP Function if YES then send message to user
$( '.Check' ).bind('click keyup', function(){
var Check = $(this).parent().children('.Check').val();
});
Add this to your .js file linked to your page and your sorted!