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up vote 19 down vote favorite
6

In one of my controller actions I am returning a very large JsonResult to fill a grid.

I am getting the following InvalidOperationException exception:

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

Setting the maxJsonLength property in the web.config to a higher value unfortunately does not show any effect.

<system.web.extensions>
  <scripting>
    <webServices>
      <jsonSerialization maxJsonLength="2147483644"/>
    </webServices>
  </scripting>
</system.web.extensions>

I don't want to pass it back as a string as mentioned in this SO answer.

In my research I came across this blog post where writing an own ActionResult (e.g. LargeJsonResult : JsonResult) is recommended to bypass this behaviour.

Is this then the only solution?
Is this a bug in ASP.NET MVC?
Am I missing something?

Any help would be most appreciated.

share|improve this question
Your solutions works on MVC 3. – MatteoSp Apr 9 at 19:31
@Matteo Are you sure? This is an old question and I can't remember but apparently I tagged it as MVC3. Unfortunately I can't see the version/date when it got fixed/closed: aspnet.codeplex.com/workitem/3436 – Martin Buberl Apr 10 at 4:35
Sure, I'm working with MVC 3 and it works. And fortunately, because in MVC 3 you don't have the "MaxJsonLength" properties cited in the accepted answer. – MatteoSp Apr 11 at 10:41

4 Answers

up vote 12 down vote accepted

It appears this has been fixed in MVC4.

You can do this, which worked well for me:

public ActionResult SomeControllerAction()
{
  var jsonResult = Json(veryLargeCollection, JsonRequestBehavior.AllowGet);
  jsonResult.MaxJsonLength = int.MaxValue;
  return jsonResult;
}
share|improve this answer
1  
Great answer! thank you! – GG. Jan 4 at 15:17
up vote 16 down vote

Unfortunately the web.config setting is ignored by the default JsonResult implementation. So I guess you will need to implement a custom json result to overcome this issue.

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up vote 13 down vote

You could also use ContentResult as suggested here instead of subclassing JsonResult.

var serializer = new JavaScriptSerializer { MaxJsonLength = Int32.MaxValue, RecursionLimit = 100 };

return new ContentResult()
{
    Content = serializer.Serialize(data),
    ContentType = "application/json",
};
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1  
in my case, working on a throwaway app, this solution worked best for me. saved implementing jsonresult. thanks! – Christo Sep 15 '12 at 22:35
up vote 0 down vote

No need for a custom class. This is all that is needed:

return new JsonResult { Data = Result, MaxJsonLength = Int32.MaxValue };

where Result is that data you wish to serialize.

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Error 137 'System.Web.Mvc.JsonResult' does not contain a definition for 'MaxJsonLength' – jaminator Jun 17 at 20:49
Where are you getting this error? – John Jun 18 at 1:07
c#.net mvc3...... – jaminator Jun 18 at 4:45
I know it works on MVC4. I will check MVC3. – John Jun 18 at 16:32

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