How To Fix Circular Reference Error When Dealing With Json

I use the following tool for serializing and deserializing JSON:

http://james.newtonking.com/pages/json-net.aspx

It's very easy to use and very lightweight.

While serializing we use this option:

JsonConvert.SerializeObject(myObject, Formatting.Indented,                             new JsonSerializerSettings {                                    ReferenceLoopHandling = ReferenceLoopHandling.Ignore                             })

It ignores circular references.

Also json.net from newtonking is extremely fast.

The other options is to use DTO's and map them via Automapper as mentioned by Diver.

Edit: I suspect your store is wrong:

var store = Ext.create('Ext.data.JsonStore', {              storeId: 'myData',        reader: new Ext.data.JsonReader({            root: 'myTable',            fields: [{ name: 'Q1', type: 'int' },                     { name: 'Q2', type: 'int' },                     { name: 'Q3', type: 'int' },                     { name: 'Q4', type: 'int' },                     { name: 'Q5', type: 'int' },                     { name: 'Improvements', type: 'string' },                     { name: 'Comments', type: 'string'}]        }),        proxy: {             type: 'json',            url: 'GridView/writeRecord'        }    });  

It's because something inside CultureInfo has a reference to itself (this type) and in process of converting to JSON it fails.To avoid this situation, you should use ViewModels (return to client only information that is needed).You can read more herehttp://blogs.msdn.com/b/dphill/archive/2009/01/31/the-viewmodel-pattern.aspx

In your situation you shoud create ViewModels for your data, convert your data to these data types and return them converted to JSON. For the purpose of converting from Model to ViewModel consider using AutoMapper http://automapper.codeplex.com/ or some similar tool.