JSON object max size?

Question

Using jquery, I'm able to send json objects from client to server using ajax like this:

var strJSON = '{"event":[{
    "dates":[
        "2009-10-14","2009-10-15"],
   "teams":[
        {"id":"0","country":"USA","state":"CA","name":"California Polytechnic State University","subteam":""},
        {"id":"1","country":"USA","state":"CA","name":"California State University, Bakersfield","subteam":""},
        {"id":"2","country":"USA","state":"CA","name":"California State University, Fresno","subteam":""},
        {"id":"3","country":"USA","state":"CA","name":"California State University, Fullerton","subteam":""}]
}]}';

$.ajax({
    url: '../ajax/save_event',
    type: 'POST',
    data: { data : strJSON },
    dataType: 'json',
    timeout: 8000,
    cache: false
});

It works well. But if the JSON string gets much bigger (not sure the exact size, but somewhere around 5x bigger), the $_POST data received by the server is empty. Anybody know why?

I'm using Apache/PHP/jquery. It happens from both IE and Firefox. Is there a config setting somewhere I need to adjust?

Here's an example of a string that fails to make it through:

{"events":[{"dates":["2009-10-10","2009-10-11","2009-10-12"],"divisions":[{"level":"Collegiate","name":"Varsity","subdivision":"Division I","rounds":[],"teams":[{"id":"0","country":"USA","state":"CA","name":"California Polytechnic State University","subteam":""},{"id":"1","country":"USA","state":"CA","name":"California State University, Bakersfield","subteam":""},{"id":"2","country":"USA","state":"CA","name":"California State University, Fresno","subteam":""},{"id":"3","country":"USA","state":"CA","name":"California State University, Fullerton","subteam":""},{"id":"4","country":"USA","state":"CA","name":"Stanford University","subteam":""},{"id":"5","country":"USA","state":"CA","name":"University of California, Davis","subteam":""},{"id":"6","country":"USA","state":"CA","name":"San Francisco State University","subteam":""},{"id":"7","country":"USA","state":"CA","name":"Lassen Community College","subteam":""},{"id":"8","country":"USA","state":"CA","name":"Menlo College","subteam":""},{"id":"9","country":"USA","state":"CA","name":"Fresno Pacific University","subteam":""},{"id":"10","country":"USA","state":"CA","name":"Bakersfield","subteam":""},{"id":"11","country":"USA","state":"CA","name":"Buchanan","subteam":""},{"id":"12","country":"USA","state":"CA","name":"Campolindo-Moraga","subteam":""},{"id":"13","country":"USA","state":"CA","name":"Fremont-Sunnyvale","subteam":""},{"id":"14","country":"USA","state":"CA","name":"Ponderosa-Shingle Springs","subteam":""},{"id":"15","country":"USA","state":"CA","name":"West Covina","subteam":""},{"id":"16","country":"USA","state":"CA","name":"Gilroy","subteam":""},{"id":"17","country":"USA","state":"CA","name":"San José State University","subteam":""},{"id":"18","country":"USA","state":"CA","name":"University of California, Los Angeles","subteam":""},{"id":"19","country":"USA","state":"CA","name":"Sierra College","subteam":""},{"id":"20","country":"USA","state":"CA","name":"Selma","subteam":""},{"id":"21","country":"USA","state":"CA","name":"Liberty","subteam":""}],}]}]}

It's created using json.org's "stringify":

var strJSON = JSON.stringify(oEvent);

EDIT: Investigating further, I changed the dataType to "text" and tried sending a long string of numbers. It works up until ~3500 characters then chokes (and when I say "choke" I mean that the request arrives at the server with a null $_POST.)

My PHP post_max_size is 64M, so that's not it. Someone suggested using Apache's "LimitRequestBody" which wasn't in httpd.conf, so I added "LimitRequestBody 0" to it and rebooted Apache. That didn't help either.

Any other suggestions???

Solution 1

This is probably due to your server's configuration. Check php.ini for the setting max_post_size and ensure that it is sufficiently large to post your data. Also check your web server settings - Apache has a LimitRequestBody directive which could be causing your problem. Finally, check your web server and PHP error logs to see if the large post is triggering any errors.

Solution 2

Just a couple of pointers to anyone else who finds this page - I ran into a similar issue with a JSON string failing to be parsed using jQuery.parseJSON().

I'm embarrassed to say my issue (probably unrelated to OP's issue) was actually caused by a stray single quote. Escaping it resolved the issue. I had orginally thought it was string length related, as it only seemed to be happening with an 8,000 character long JSON string, but it was the stray quote terminating the string in the wrong place.

Tim, I don't know if you ever got to the bottom of your original issue, but pasting the string you supplied:

{"events":[{"dates":["2009-10-10","2009-10-11","2009-10-12"],"divisions":[{"level":"Collegiate","name":"Varsity","subdivision":"Division I","rounds":[],"teams":[{"id":"0","country":"USA","state":"CA","name":"California Polytechnic State University","subteam":""},{"id":"1","country":"USA","state":"CA","name":"California State University, Bakersfield","subteam":""},{"id":"2","country":"USA","state":"CA","name":"California State University, Fresno","subteam":""},{"id":"3","country":"USA","state":"CA","name":"California State University, Fullerton","subteam":""},{"id":"4","country":"USA","state":"CA","name":"Stanford University","subteam":""},{"id":"5","country":"USA","state":"CA","name":"University of California, Davis","subteam":""},{"id":"6","country":"USA","state":"CA","name":"San Francisco State University","subteam":""},{"id":"7","country":"USA","state":"CA","name":"Lassen Community College","subteam":""},{"id":"8","country":"USA","state":"CA","name":"Menlo College","subteam":""},{"id":"9","country":"USA","state":"CA","name":"Fresno Pacific University","subteam":""},{"id":"10","country":"USA","state":"CA","name":"Bakersfield","subteam":""},{"id":"11","country":"USA","state":"CA","name":"Buchanan","subteam":""},{"id":"12","country":"USA","state":"CA","name":"Campolindo-Moraga","subteam":""},{"id":"13","country":"USA","state":"CA","name":"Fremont-Sunnyvale","subteam":""},{"id":"14","country":"USA","state":"CA","name":"Ponderosa-Shingle Springs","subteam":""},{"id":"15","country":"USA","state":"CA","name":"West Covina","subteam":""},{"id":"16","country":"USA","state":"CA","name":"Gilroy","subteam":""},{"id":"17","country":"USA","state":"CA","name":"San José State University","subteam":""},{"id":"18","country":"USA","state":"CA","name":"University of California, Los Angeles","subteam":""},{"id":"19","country":"USA","state":"CA","name":"Sierra College","subteam":""},{"id":"20","country":"USA","state":"CA","name":"Selma","subteam":""},{"id":"21","country":"USA","state":"CA","name":"Liberty","subteam":""}],}]}]}

into http://json.parser.online.fr/ gives the following error, if this is of any help to anyone else:

SyntaxError: JSON.parse: expected double-quoted property name

Solution 3

It seems like there is a size issue, when testing my Json string everything works when the string is small ,when I increment the string (php array to be encoded) the output of the Json string gets chopped off.

when doing a string length on the failed string , I get (7796) . So I changed the max post option in the ini file both for the cli and apache to 64M instead of 8M and I am still getting the same problem. I do not think this problem is restricted to the apache LimitRequestBody since the php gives the same output on CLI.

One more thing, when doing a var_dump on the encoded json string, I can see when it gets chopped of and the json tags do not get closed, hence why the Json decoder return a null.

e.g

$strJson = file_get_contents('http://mydomain/page');
var_dump($strJson);

You will see where the string is being chopped off and a zero is concatenated to end of the output.

Solution 4

'jsonp' datatype does not and can not use the POST method. Instead all data is passed in a query string. Thus, if the server's max query string length is exceeded, the data will not be passed. The reason for this is that jQuery loads the json data as a node into your html document, and this can only be done as a GET. If you need more data you'll have to use XML or other.

View more solutions

Comments

[rfunduk]

Can you try and have it not a string to start? As in, just have a JavaScript object that you pass to the data parameter of the ajax call. See what happens.

[Asaph]

Please post an example of failing JSON. 5x bigger than what you have posted is not really that big. It might be an escaping problem or structure problem in your JSON string.

[Admin]

Alright, I just added an example above. It's created with stringify().

[rfunduk]

No no I mean literally pass the object to data: rather than using any sort of stringify at all. Pass jQuery the Object, it will turn it into JSON. If that still fails then it's probably what pix0r said, server configuration issue.

[Crescent Fresh]

@thenduks: jQuery does not serialize anything to JSON. If you pass .ajax an object you get the standard foo=1&bar=2 request body/query generated for you. If the OP wants JSON then JSON.stringify is the way to go.

[Admin]

I tested it out, and it's not what thenduks suggested. If I do that, I receieve a JSON object (instead of a string) in $_POST, and I don't think PHP knows what to do with that. (PHP's json_decode() needs a string passed to it.) Anyways, it after further review, it isn't a JSON issue at all. If I change dataType to 'text' and send just a long string of text, it works only up to about 3500 chaacters (see my new comments above).

[Blaise]

so how is this problem fixed?

[Vladimir Ch]

mb increase max_input_vars + check for other limitations.serverOS/browser e t.c.

[Admin]

I thought that too, but this is what it reads: post_max_size = 64M That's 64 megabytes, correct?

[pix0r]

Also check httpd.conf for LimitRequestBody

[pix0r]

(and yes, 64M == 64 megabytes).

[Admin]

I set "LimitRequestBody 0" (unlimited) in httpd.conf and rebooted Apache. It had no effect. Any other ideas?

[solefald]

Ronald, were you ever able to find a solution to this? I am facing exact same issue, though my string gets cut off at 3127 characters

[intellitecture]

Should have specified (thought I did): The json request is sent by adding a <script> node to your html doc. All data is passes in a query string. Ex.: <script src="script.js?data1=example&data2=... There is no way to send POST data in a <script> tag. Ergo, the size of the data is limited by the server's maximum size for query strings / URLs.

[Rup]

An anonymous user comments: There is a trailing comma after the array which is likely causing this error: ..."Liberty","subteam":""}],}]}]} This is incorrect JSON. Some browsers can recover by ignoring trailing commas, but some cannot parse it.

[Vladimir Ch]

and probably limit of of your browser =)