ASP.NET MVC route for serverside imagemap

Question

I've got an <input type='image'> in an ASP.NET MVC view, but I'm not sure how to retrieve the coordinates in the action that runs when the form is submitted. The requested URL looks like

/Map/View/?map.x=156&map.y=196

but I can't just do

public ActionResult View( int map.x, int map.y )
{
  ...
}

because they're obviously not valid names for C# method parameters. Is there any equivalent of the ActionName attribute to map query parameters to method parameters?

Answer 1

You have to use use Model binder and set the prefix property to "map":

First create the Model object:

public class ImageMap()
{
  public int x{get;set;}
  public int y{get;set;}
}

And in your action method:

public ActionResult About([Bind(Prefix="map")]ImageMap map)
{

   // do whatever you want here
    var xCord = map.x;

}

Answer 2

You could make a class like this:

public class ImageMap()
{
  public int x{get;set;}
  public int y{get;set;}
}

and then use that as a parameter for your action method

public ActionResult View(ImageMap map)
{
  ...
}

Answer 3

Try IModelBinders. See this, this and this question.

Answer 4

You can try an entirely different approach and build up your image map using the code provided in the following link.

http://www.avantprime.com/articles/view-article/9/asp.net-mvc-image-map-helper

Answer 5

To answer your question directly, you can change the field which is used on a parameter by using [Bind]:

public ActionResult View([Bind(Prefix="map.x")] int x, 
    [Bind(Prefix="map.y")] int y )

However, a custom ModelBinder that bound an image map to a System.Drawing.Point struct would be nicer.

Edit: Here is an ImageMapBinder that automatically maps to a System.Drawing.Point argument. You don't have to decorate each Point argument with an attribute as long as you add the following code to your Application_Start:

ModelBinders.Binders.Add(typeof(Point), new ImageMapBinder());

Though you can still rename the input using [Bind(Prefix="NotTheParameterName")] if you want to.

The code for ImageMapBinder is as follows:

public class ImageMapBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, 
        ModelBindingContext bindingContext)
    {
        int x, y;

        if (!(ParseValue(bindingContext, "x", out x) &&
            ParseValue(bindingContext, "y", out y)))
        {
            return Point.Empty;
        }

        return new Point(x, y);
    }

    private bool ParseValue(ModelBindingContext bindingContext, string value, 
        out int outValue)
    {
        string key = String.Concat(bindingContext.ModelName, ".", value);

        ValueProviderResult result = bindingContext.ValueProvider[key];

        if (result == null)
        {
            outValue = 0;
            return false;
        }

        return ParseResult(result, out outValue);
    }

    private bool ParseResult(ValueProviderResult result, out int outValue)
    {
        if (result.RawValue == null)
        {
            outValue = 0;
            return false;
        }

        string value = (result.RawValue is string[])
            ? ((string[])result.RawValue)[0]
            : result.AttemptedValue;

        return Int32.TryParse(value, out outValue);
    }
}