Adding multiple Prefixes to DefaultModelBinder MVC2

Question

I've looked at most of the ModelBinding examples but can't seem to glean what I'm looking for.

I'd like:

<%= Html.TextBox("User.FirstName") %>
<%= Html.TextBox("User.LastName") %>

to bind to this method on post

public ActionResult Index(UserInputModel input) {}

where UserInputModel is

public class UserInputModel {
    public string FirstName {get; set;}
    public string LastName {get; set;}
}

The convention is to use the class name sans "InputModel", but I'd like to not have to specify this each time with the BindAttribute, ie:

public ActionResult Index([Bind(Prefix="User")]UserInputModel input) {}

I've tried overriding the DefaultModelBinder but can't seem to find the proper place to inject this tiny bit of functionality.

score 2 · Answer 1 · answered Sep 10 '11 at 16:30

The ModelName property in the ModelBindingContext object passed to the BindModel function is what you want to set. Here's a model binder that does this:

 public class PrefixedModelBinder : DefaultModelBinder
 {
     public string ModelPrefix
     {
         get;
         set;
     }

     public PrefixedModelBinder(string modelPrefix)
     {
         ModelPrefix = modelPrefix;
     }

     public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
     {
         bindingContext.ModelName = ModelPrefix;
         return base.BindModel(controllerContext, bindingContext);
     }
 }

Register it in your Application_Start like so:

ModelBinders.Binders.Add(typeof(MyType), new PrefixedModelBinder("Content"));

Now you will no longer to need to add the Bind attribute for types you specify use this model binder!

+1 for the inspiration, it helped me solve a long running problem — Odys, Jul 04 '14 at 20:58

Derek Greer · Answer 2 · 2010-07-18T14:48:14.197

1

The BindAttribute can be used at the class level to avoid duplicating it for each instance of the UserInputModel parameter.

======EDIT======

Just dropping the prefix from your form or using the BindAttribute on the view model would be the easiest option, but an alternative would be to register a custom model binder for the UserInputModel type and explicitly looking for the prefix you want.

edited Jul 18 '10 at 14:48

answered Jul 18 '10 at 07:12

Derek Greer

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That's good to know, and makes my task more manageable. Though I'd still like to know if this can be done behind the scenes in the model binding process since the attribute requires constant values. – Mitch Rosenburg Jul 18 '10 at 14:01
Maybe my original question wasn't clear. I'd like to know HOW to derive from the DefaultModelBinder and add this extra prefix check there based on the model type. – Mitch Rosenburg Jul 20 '10 at 13:55

Adding multiple Prefixes to DefaultModelBinder MVC2

2 Answers2