I understand that ASP.NET Web API natively uses Json.NET for (de)serializing objects, but is there a way to specify a JsonSerializerSettings object that you want for it to use?
For example, what if I wanted to include type information into the serialized JSON string? Normally I'd inject settings into the .Serialize() call, but Web API does that silently. I can't find a way to inject settings manually.
You can customize the JsonSerializerSettings by using the Formatters.JsonFormatter.SerializerSettings property in the HttpConfiguration object.
For example, you could do that in the Application_Start() method:
protected void Application_Start() { HttpConfiguration config = GlobalConfiguration.Configuration; config.Formatters.JsonFormatter.SerializerSettings.Formatting = Newtonsoft.Json.Formatting.Indented; } 
You can specify JsonSerializerSettings for each JsonConvert, and you can set a global default.
Single JsonConvert with an overload:
// Option #1. JsonSerializerSettings config = new JsonSerializerSettings { ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore }; this.json = JsonConvert.SerializeObject(YourObject, Formatting.Indented, config); // Option #2 (inline). JsonConvert.SerializeObject(YourObject, Formatting.Indented, new JsonSerializerSettings() { ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore } ); Global Setting with code in Application_Start() in Global.asax.cs:
JsonConvert.DefaultSettings = () => new JsonSerializerSettings { Formatting = Newtonsoft.Json.Formatting.Indented, ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore }; Reference: https://github.com/JamesNK/Newtonsoft.Json/issues/78
HttpConfiguration instead as in carlosfigueira's answer as settings configured in JsonConvert.DefaultSettings were not being observed.JsonSerializerSettings is what worked for me. I could not get the HttpCOnfiguration to work, it was comming back with another assemblies methods (Hangifre) not sure why.
formHiddenField.Value = JsonConvert.SerializeObject(listaCursos, Formatting.Indented, jsonSerializerSettings); and use JQuery for get the value var data = $('#formHiddenField').val(); ?Answer is adding this 2 lines of code to Global.asax.cs Application_Start method
var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter; json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.All; Reference: Handling Circular Object References
