MVC3 Unable To Return Large JSON Even with Web Config Patch, Using LargeJsonResult Instead

I’m trying to download a base64 encoded image that is about 4 Megabytes embedded inside a JSON object.  When I first tried this from my MVC3 Web application, I got the error:

Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property.

I then tried to set the web.config property that everyone seems to reference on the web as follows:

            <jsonSerialization maxJsonLength="2147483645" recursionLimit="100">

However, I kept getting the same error over and over.  So, I used the technique suggested in this article

by Brian Reiter to create an override of the JsonResult class.  That actually worked for me, however unfortunately, it does not show the shape of the data that is currently being returned by MVC3.  That is, MVC3 currently returns a JsonResult as follows:

return Json(new
    total = blobs.Count,
    data = blobs.ToList()
}, JsonRequestBehavior.AllowGet);
Brian suggest in his article to return his LargeJsonResult, do the following:
return new LargeJsonResult() { Data = output, MaxJsonLength = int.MaxValue };
This does not quite work for what I want.  For my result to work, I needed to modify the result a little and return it as follows:
   new LargeJsonResult
           MaxJsonLength = 20000000,
           JsonRequestBehavior = JsonRequestBehavior.AllowGet,
           Data = new
                          total = blobs.Count,
                          data = blobs.ToList()
Not much different, but does solve my problem.
Thanks Brian for the nice contribution!
About Peter Kellner

Peter is a software professional specializing in mobile and web technologies. He has also been a Microsoft MVP since 2007. In addition, he's a multi-course video author at Pluralsight. To read more about Peter Kellner and his experience click here. For information about how Peter Kellner might be able to help you with your project click here.

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  1. Sorry Brian. I think I’ve fixed it now.

  2. Hi Peter,

    Thanks for your pingback when blogging about LargeJsonResult but you made a mistake in attribution. My name is Brian Reiter. Bruce Schneier is a cryptographer at the top of my blog roll.



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