Cannot set a custom contract resolver in web api configuration - asp.net

Question

How can I set a custom contract resolver in web api configuration? My code is relatively new and has no custom contract resolver till now.
I have added no other customization besides routing.
I tried in three different ways and none worked:
public static void Register(HttpConfiguration config)
{
// Web API routes
config.MapHttpAttributeRoutes();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{action}/{id}",
defaults: new { id = RouteParameter.Optional }
);
//attempt 1
config.Formatters.JsonFormatter.SerializerSettings.ContractResolver = new CustomContractResolver();
//attempt 2
GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ContractResolver = new CustomContractResolver();
//attempt 3
JsonConvert.DefaultSettings = () => new JsonSerializerSettings
{
ContractResolver = new CustomContractResolver()
};
}
The custom contract resolver code, breakpoint never reaches here when I'm debugging:
public class CustomContractResolver : CamelCasePropertyNamesContractResolver
{
protected override string ResolvePropertyName(string propertyName)
{
var regex = new Regex(#"([_])(\w)");
if (regex.IsMatch(propertyName))
{
var result = regex.Replace(propertyName.ToLower(), (match) => { return match.Groups[2].Value.ToUpper(); });
return result;
}
else
return base.ResolvePropertyName(propertyName);
}
}
Is there something that is missing?
Edit 1:
I'm using ASP.NET WebApi 5.2.1 AND MVC 5.2.7, JSON.NET (Newtonsoft.Json) v13.0.1 (and already tried the old v12)
My Global Asax is very simple as well:
public class MvcApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
GlobalConfiguration.Configure(WebApiConfig.Register); //<- web api configuration
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes); //<- mvc configuration
BundleConfig.RegisterBundles(BundleTable.Bundles);
}
}
The MVC RouteConfig class:
public class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.IgnoreRoute("{resource}.ashx/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
}
Edit 2
Here is some test web api controllers:
using System.Web.Http;
namespace Kronos.Web.Geolocalizacao.Controllers.Api
{
public class TestController : ApiController
{
[HttpGet]
public TestModel Obtain()
{
return new TestModel { CODE_IDENTIFICATION = 1, DEFAULT_DESCRIPTION = "TEST DAT THING" };
}
}
public class TestModel
{
public decimal CODE_IDENTIFICATION { get; set; }
public string DEFAULT_DESCRIPTION { get; set; }
}
}
Used the Tabbed Postman chrome addon to test
Postman tests

Answer 1

Your problem has nothing to do with how you are registering your global settings -- setting config.Formatters.JsonFormatter.SerializerSettings.ContractResolver is correct as per this question. Your problem is that Json.NET does not call ResolvePropertyName() when the contract resolver also has a NamingStrategy -- and your base class CamelCasePropertyNamesContractResolver does indeed have a naming strategy.
This can be verified by checking the current Json.NET reference source for DefaultContractResolver.SetPropertySettingsFromAttributes():
if (namingStrategy != null)
{
property.PropertyName = namingStrategy.GetPropertyName(mappedName, hasSpecifiedName);
}
else
{
property.PropertyName = ResolvePropertyName(mappedName);
}
Broken demo fiddle #1 here.
If I simply modify your CustomContractResolver to inherit from DefaultContractResolver (which has a null NamingStrategy by default), then it works:
public class CustomContractResolver : DefaultContractResolver
{
readonly NamingStrategy baseNamingStrategy = new CamelCaseNamingStrategy();
protected override string ResolvePropertyName(string propertyName)
{
var regex = new Regex(#"([_])(\w)");
if (regex.IsMatch(propertyName))
{
var result = regex.Replace(propertyName.ToLower(), (match) => { return match.Groups[2].Value.ToUpper(); });
return result;
}
else
return baseNamingStrategy.GetPropertyName(propertyName, false);
}
}
Fixed demo fiddle #2 here.
However, a cleaner solution would be to replace your custom contract resolver with a custom naming strategy:
public class CustomNamingStrategy : CamelCaseNamingStrategy
{
public CustomNamingStrategy() : base() { }
public CustomNamingStrategy(bool processDictionaryKeys, bool overrideSpecifiedNames) : base(processDictionaryKeys, overrideSpecifiedNames) { }
public CustomNamingStrategy(bool processDictionaryKeys, bool overrideSpecifiedNames, bool processExtensionDataNames) : base(processDictionaryKeys, overrideSpecifiedNames, processExtensionDataNames) { }
readonly Regex regex = new Regex(#"([_])(\w)");
protected override string ResolvePropertyName(string name)
{
if (regex.IsMatch(name))
{
var result = regex.Replace(name.ToLower(), (match) => { return match.Groups[2].Value.ToUpper(); });
return result;
}
return base.ResolvePropertyName(name);
}
}
And then configure it in settings like so:
settings.ContractResolver = new DefaultContractResolver
{
// Set the constructor parameters as per your preference. These values are consistent with CamelCasePropertyNamesContractResolver
NamingStrategy = new CustomNamingStrategy(processDictionaryKeys: true, overrideSpecifiedNames: true),
};
Demo fiddle #3 here.