MVC4：从字符串到对象的映射中获得有用的模型绑定的最简单方法

Question

I'm in an MVC controller. I have a class, and I would like MVC to treat values of this class in exactly the same way it would treat a Guid or a DateTime ; that is:

• When an instance of the class type is written out to a form, it is as a single formatted string and not as separate fields.
• When a value (in string form) is posted back, it is automatically converted back to an instance of the class.

Conceptually, implementing this ought to require only a conversion function for each direction. Say we have one or more objects implementing this interface:

namespace SomeExample
{
    public interface SomeStringConversion<T>
    {
        T ConvertFromString(string str);
        string ConvertToString(T obj);
    }
}

// Example: What such a class for Guid might look like
namespace SomeExample
{
    public class SomeGuidStringConversion : SomeStringConversion<Guid>
    {
        public Guid ConvertFromString(string str)
        {
            return Guid.Parse(str);
        }

        public string ConvertToString(Guid g)
        {
            return g.ToString();
        }
    }
}

And say we don't care to validate above and beyond what is accepted or rejected by ConvertFromString() .

What is the straightest path (ie with as little extraneous detail as possible about unrelated features of model binding) from a collection of SomeStringConversion<T> to a controller that uses them?

EDIT: I've been a developer for a good while but I'm fresh meat when it comes to MVC. I need an example with code from which I can work backwards. A high-level description won't be much assistance.

Answer 1

The most straightfoward way that I can see to implement this would be with a custom model binder.

The binder checks to see if the model type to bind implements the SomeStringConversion<T> interface and if it does, attempts to bind the model to the incoming string value. If it doesn't, it simply defers to DefaultModelBinder to take the default model binding course of action.

If the string structure is well-formed you may be able to implement a ValueProvider to provide the values to a model binder for model binding.