JsonValueProviderFactory throws “request too large”

Question

I\'m getting an exception that the JSON request was too large to be deserialized.

It\'s coming from the JsonValueProviderFactory....

The MVC App currently

Answer 1

If you use JSON.NET for serialization/deserialization, you could substitute the default JsonValueProviderFactory with a custom one as shown in this blog post:

public sealed class JsonDotNetValueProviderFactory : ValueProviderFactory
{
   public override IValueProvider GetValueProvider(ControllerContext controllerContext)
   {
        if (controllerContext == null)
            throw new ArgumentNullException("controllerContext");

        if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
            return null;

        var reader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
        var bodyText = reader.ReadToEnd();

        return String.IsNullOrEmpty(bodyText) ? null : new DictionaryValueProvider<object>(JsonConvert.DeserializeObject<ExpandoObject>(bodyText, new ExpandoObjectConverter()) , CultureInfo.CurrentCulture);
    }
}

and in your Application_Start:

ValueProviderFactories.Factories.Remove(ValueProviderFactories.Factories.OfType<JsonValueProviderFactory>().FirstOrDefault());
ValueProviderFactories.Factories.Add(new JsonDotNetValueProviderFactory());

and if you want to stick with the default factory which uses the JavaScriptSerializer class you could adjust the maxJsonLength property in your web.config:

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

Answer 2

The above suggestions didn't work for me until I tried this:

// Global.asax.cs    
protected void Application_Start() {
    MiniProfiler.Settings.MaxJsonResponseSize = int.MaxValue;
}

Answer 3

For me, the maxJsonLength was not being exceeded. I had to add the following:

<appSettings>
  <add key="aspnet:MaxJsonDeserializerMembers" value="150000" />
</appSettings>

It worked a treat after that.