R – ASP.NET MVC ModelBinding Inherited Classes

asp.net-mvcinheritancemodelbinders

I've got a question about ModelBinding in ASP.NET MVC (I'm using MVC 2 preview 2) related to inheritance.

Say I have the following interfaces/classes:

interface IBase
class Base : IBase
interface IChild
class Child: Base, IChild

And I have a custom model binder BaseModelBinder.

The following work fine:

ModelBinders.Binders[typeof(Child)] = new BaseModelBinder();
ModelBinders.Binders[typeof(IChild)] = new BaseModelBinder();

The following do not work (on binding a on object of type Child):

ModelBinders.Binders[typeof(Base)] = new BaseModelBinder();
ModelBinders.Binders[typeof(IBase)] = new BaseModelBinder();

Is there any way to have a model binder for a base class that will apply to all inherited classes? I really don't want to have to manually input something for every possible inheriting class.

Also, if it is possible, is there a way to override the modelbinder for a specific inheriting class? Say I got this working but I needed a specific modelbinder for Child2.

Thanks in advance.

Best Answer

I took a simple route, I just register all derived classes dynamically at startup using reflection. Maybe it's not a clean solution, but it's couple of lines in the initialization code that just works ;-)

But if you really want to mess with model binders (you'll HAVE to - eventually - but there're better ways to spend your time ;-) you can read this and this.

Related Solutions

Asp.net-mvc – Compile Views in ASP.NET MVC

From the readme word doc for RC1 (not indexed by google)

ASP.NET Compiler Post-Build Step

Currently, errors within a view file are not detected until run time. To let you detect these errors at compile time, ASP.NET MVC projects now include an MvcBuildViews property, which is disabled by default. To enable this property, open the project file and set the MvcBuildViews property to true, as shown in the following example:

<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <MvcBuildViews>true</MvcBuildViews>
  </PropertyGroup>

Note Enabling this feature adds some overhead to the build time.

You can update projects that were created with previous releases of MVC to include build-time validation of views by performing the following steps:

Open the project file in a text editor.
Add the following element under the top-most <PropertyGroup> element: <MvcBuildViews>true</MvcBuildViews>
At the end of the project file, uncomment the <Target Name="AfterBuild"> element and modify it to match the following:

<Target Name="AfterBuild" Condition="'$(MvcBuildViews)'=='true'">
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C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
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   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
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    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common