ASP.net MVC - Model binding excludes class fields?

Question

In a recent project - i\'ve hit an unexpected snag.
A class with simple public fields (note not properties) doesn\'t seem to want to play nice with the ASP.net MVC 3.0

Answer 1

I know it's against the c# team's philosophy, but I think fields are clean in poco classes. Seems like less moving parts to me. Anyway,

Here's a model binder that will load fields. It's fairly trivial. Note that you can use a new object with Activator.CreateInsance or start with an existing object as a starting point. I was using Yes/No dropdowns for bool, you may have check boxes, in which case unfortunately you'll have to loop through fieldinfos and look for missing form inputs b/c html doesn't submit form items if it's a false checkbox.

~/Binders/FieldModelBinder.cs

using System;
using System.Reflection;
using System.Web.Mvc;

namespace MyGreatWebsite.Binders
{
  public class FieldModelBinder : DefaultModelBinder
  {
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
      var obj = controllerContext.HttpContext.Session["CurrentObject"];// Activator.CreateInstance(bindingContext.ModelType);
      var form = controllerContext.HttpContext.Request.Form;
      foreach (string input in form)
      {
        FieldInfo fieldInfo = obj.GetType().GetField(input);
        if (fieldInfo == null)
          continue;
        else if (fieldInfo.FieldType == typeof(bool))
          fieldInfo.SetValue(obj, form[input] == "Yes");
        else
          fieldInfo.SetValue(obj, Convert.ChangeType(form[input], fieldInfo.FieldType));
      }
      return obj;
    }
  }
}

Startup.cs

  public partial class Startup
  {
    public void Configuration(IAppBuilder app)
    {
      ConfigureAuth(app);
      ModelBinders.Binders.Add(typeof(FieldModelBinder), new FieldModelBinder());
    }
  }

Usage

[HttpPost]
public ActionResult MyGreatAction([ModelBinder(typeof(FieldModelBinder))] MyGreatProject.MyGreatNamespace.MyGreatType instance, string myGreatParameters)
{
  DoSomethingGreatWithMyInstance();
  return View();
}