ASP.NET MVC 2 Model子类始终为null

Question

I have a problem with passing values from model to controller, let's say i have two classes:

public class Model
{
    public string Name { get; set; } 
    public SubClass Value { get; set; } 
}
public class SubClass
{
    public string Value1 { get; set; }
    public string Value2 { get; set; }
}

in view, I'm assigning values to Model's property value of type SubClass like this :

<%: Html.TextBoxFor(model => model.Value.Value1) %> 

<%: Html.TextBoxFor(model => model.Value.Value1) %>

The view is passing to controller only the Name property of Model, the Value property always stays null. Any suggestions ?

Answer 1

This is because by default, the MVC model binder won't pass (complex ie non-primitive types) sub-types back to the controller on a post. Your property public SubClass Value { get; set; } public SubClass Value { get; set; } public SubClass Value { get; set; } is a complex type (a class you've written called SubClass).

You need to write a custom model binder for this, to tell MVC how to post sub-class(es) back with your model. Here's some great articles on custom model binding to help you get to where you need to be.

http://odetocode.com/Blogs/scott/archive/2009/04/27/12788.aspx

http://odetocode.com/Blogs/scott/archive/2009/05/05/12801.aspx

Answer 2

In your controller you have to get the model :

[httpost]
public void action(Model model)
{
   //get your subClass values
    string s = model.Value.Value1;         
}