ImageActionLink Newbe Redux

I've been beating my head for hours now, so I'll ask...

In all examples for ImageActionBuilders the method looks like:

public static class ImageActionLinkHelper 
    { 
        public static string ImageActionLink(this AjaxHelper helper, string imageUrl, string actionName, object routeValues, AjaxOptions ajaxOptions) 
        { 
            var builder = new TagBuilder("img"); 
            builder.MergeAttribute("src", imageUrl); 
            builder.MergeAttribute("alt", ""); 
            var link = helper.ActionLink(builder.ToString(TagRenderMode.SelfClosing), actionName, routeValues, ajaxOptions); 
            return link.ToHtmlString(); 
        } 
    } 

I created a class library, included the method, referenced it in my project and I can see it.

The cal开发者_运维技巧l in the View (.chtml) is documented like this:

@jax.ImageActionLink("../../Content/Images/button_add.png", "JobTasksNew", "TrackMyJob",new AjaxOptions { HttpMethod = "GET", UpdateTargetId = "tmjDynamic" })) 

Being new to C#, the first parameter (this Ajaxhelper helper) is never referenced in the call from the View in any of the posts here.

The compiler on my machine is complaining about missing a parameter when I structure a call identical to the one above.

I'm missing something. How is the first parameter getting passed or resolved?

Thank you.

If you are new to C# the first and foremost thing that you should do before jumping into ASP.NET MVC is to read about extension methods in C#. What they are and how they work. Really it's a personal advice I can give you : learn C#/VB.NET before jumping into ASP.NET MVC. It's like trying to build a car without having discovered the combustion engine.

That's what HTML helpers in ASP.NET MVC are: extension methods. In your example you have defined the ImageActionLink extension method inside the ImageActionLinkHelper static class. Supposing that this class is defined in the Foo namespace:

namespace Foo
{
    public static class ImageActionLinkHelper 
    { 
        public static string ImageActionLink(this AjaxHelper helper, string imageUrl, string actionName, object routeValues, AjaxOptions ajaxOptions) 
        {
            ...
        }
    }
}

You should bring this Foo namespace into scope inside the view so that your extension method is available:

@using Foo
...
@Ajax.ImageActionLink("../../Content/Images/button_add.png", "JobTasksNew", "TrackMyJob",new AjaxOptions { HttpMethod = "GET", UpdateTargetId = "tmjDynamic" })) 

or if you want it to be available in all Razor views of your ASP.NET MVC 3 application you should add the Foo namespace inside the <namespaces> section of the ~/Views/web.config file.