ASP.NET MVC 3 binding user control of type KeyValuePair to ViewModel

Question

I have created a special User Control which inherits KeyValuePair. Inside my ViewModel, there is a property called lookup

[UIHint("Lookup")]
public KeyValuePair<string, string> lookup { get; set; }

User Control is

Html.TextBoxFor(m => m.Value, new { id = "Name", style = "width: 200px; background-color: #C0C0C0" })

Html.HiddenFor(m => m.Key, new { id="Guid"})

The user Control has some Jquery statements which set the value of the TextBox and the Hidden field.

When I do a DEBUG to the POST method of the Controller, I see no value inside the Lookup property?!

But If I changed the type of the property to string instead of KeyValuePair and also change the type of the User Control, I see a value.

I think I'm very close but I can't figure it out.

score 4 · Accepted Answer · answered Dec 16 '11 at 19:06

4

The KeyValuePair structure doesn't have a default parameterless constructor and can't be instantiated by the model binder. I recommend a custom model class for your view that has just those properties.

public class CustomControlViewModel
{
    public string Key { get; set; }
    public string Value { get; set; }
}

Transform your KVP into this model class for your view and/or use this class as the parameter on your action.

[HttpGet]
public ActionResult Lookup()
{
    return View( new CustomControlViewModel { Value = kvp.Value, Key = kvp.Key } );
}

[HttpPost]
public ActionResult Lookup( CustomControlViewModel lookup )
{
     ...
}

answered Dec 16 '11 at 19:06

tvanfosson

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Thank you so much, that's exactly what I want. – Anwar Dec 16 '11 at 19:29
Why it doesn't work if it works properly using Dictionary, that implements > ? – Mario Levrero Nov 06 '13 at 16:47
@MarioLevrero I assume (without checking) that the model binder for a dictionary uses the Add method to update the dictionary. – tvanfosson Nov 06 '13 at 17:42

ASP.NET MVC 3 binding user control of type KeyValuePair to ViewModel

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