jQuery.ajax call sometimes doesn't fire C# WebMethod

Question

I have a jQuery.ajax call on a button click event in my webpage. This ajax call sends quite a lot of markup back to the server. After some processing the server posts back a small URL address. This works fine sometimes but other times doesn't. I have a breakpoint just before the ajax call and also have some in my WebMethod. It appears that sometimes the WebMethod doesn't even get hit.

What could be causing the .ajax call to fail? I'm assuming there must be something in the parameters I am sending. But I am escapeing the markup.

Anyone got any ideas?

$.ajax({
    type: 'POST',
    url: 'WebServices.asmx/GetBitmapPathForVML',
    contentType: 'application/json; charset=utf-8',
    data: '{"sVML" : "' + escape($('#divChart')[0].innerHTML) + 
      '","width" : 800,"height": 600}',
    dataType: 'json',
    success: function(result) {
            var newWindow = window.open ("", "Chart","");
            //blah blah
            newWindow.document.write("<BODY>");
            newWindow.document.write(
              '<img src="file" alt="Chart"></img>'.replace('file',result.d)
            );  
            newWindow.document.write("</BODY>");    
            //blah blah
    }
});

Are you able to hit the service all the time otherwise if you post nothing (null) to the method? — dexter
– dexter, Commented Jan 10, 2011 at 15:06
Check "error" and "timeout" options for jQuery ajax, that should help you. Also if there's some problem with the way you're calling the webservice, you should get a script error from the client. — Jamie Treworgy
– Jamie Treworgy, Commented Jan 10, 2011 at 15:07
@jamietre Thanks, I caught the error. The length of the string exceeds the value set on the maxJsonLength property Any idea how I can handle this? — El Ronnoco
– El Ronnoco, Commented Jan 10, 2011 at 15:16
Maybe cache issue.. try to disable cache by adding cache: false to the settings. — user447356
– user447356, Commented Jan 10, 2011 at 15:17
@El Ronnoco, see this: stackoverflow.com/questions/1151987/unlimited-for-maxjsonlength ... however rather than trying to adjust the max allowed size you should think about the architecture, why are you sending a whole HTML table back to the client? Probably you should extract just the relevant data and send that. That should be pretty easy with jquery. If you really want to do this for some reason you might have to break it into chunks and call the service multiple times. — Jamie Treworgy
– Jamie Treworgy, Commented Jan 10, 2011 at 15:23

Darin Dimitrov · Accepted Answer · 2011-01-10 15:06:14Z

2

I would recommend you rewriting your method like this:

$.ajax({
    type: 'POST',
    url: 'WebServices.asmx/GetBitmapPathForVML',
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify({
        sVML: $('#divChart').html(),
        width: 800,
        height: 600
    }),
    dataType: 'json',
    success: function(result) {
        var newWindow = window.open ("", "Chart","");
        //blah blah
        newWindow.document.write("<BODY>");
        newWindow.document.write(
            '<img src="file" alt="Chart"></img>'.replace('file',result.d)
        );  
        newWindow.document.write("</BODY>");    
        //blah blah
    }
});

answered Jan 10, 2011 at 15:06

Darin Dimitrov

1.0m275 gold badges3.3k silver badges3k bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

El Ronnoco Over a year ago

Which library do I need to use JSON.stringify?

Darin Dimitrov Over a year ago

json2.js. But this method is natively implemented in modern browsers and the library simply delegates the call to the native method if supported. So if you are using a modern browser you don't need to include anything.

El Ronnoco Over a year ago

I'm afraid I'm forced to develop for IE6. :O

El Ronnoco Over a year ago

This is good advice as I wasn't happy with my JSON construction. I will endeavour to use this in future projects however in this instance this was not the cause of my problem.

Tiago Deliberali Santos · Accepted Answer · 2011-01-10 15:17:59Z

1

El Ronnoco,

I would suggest you to add a error: callback to check what is going on. Maybe you can get usefull information from that.

answered Jan 10, 2011 at 15:17

Tiago Deliberali Santos

5043 silver badges9 bronze badges

Comments

Community · Accepted Answer · 2017-05-23 10:33:08Z

1

Don't like answering my own question (not that I am, really). But the issue was to do with the maximum JSON length property.

I found the answer here

..and added this to my webconfig...

<system.web.extensions>
    <scripting>
        <webServices>
            <jsonSerialization maxJsonLength="2097152"/>
        </webServices>
    </scripting>
</system.web.extensions>

Thanks for all the answers guys, especially those about catching the errors.

edited May 23, 2017 at 10:33

CommunityBot

11 silver badge

answered Jan 10, 2011 at 15:29

El Ronnoco

11.9k5 gold badges41 silver badges67 bronze badges

Collectives™ on Stack Overflow

jQuery.ajax call sometimes doesn't fire C# WebMethod

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related