Extend Viewpage class with custom helper objects?

Question

Is it possible to add a custom helper object to the ViewPage class, so I can use it inside the view page markup (just like Html, Url and Ajax) ? This helper object also needs some data from a custom controller. (which should be possible through the ViewContext property I think)

Answer 1

Create new class, derive it from System.Web.Mvc.ViewPage, add new property for custom helper and override InitHelpers() method. For example:

public class CustomViewPage : System.Web.Mvc.ViewPage
{
    public YourCustomHelper CustomHelper
    {
        get;
        set;
    }

    public virtual void InitHelpers()
    {
        CustomHelper = new YourCustomHelper(ViewContext);

        base.InitHelpers();
    }
}


public class YourCustomHelper
{
    public YourCustomHelper(ViewContext viewContext)
    {
        if (viewContext == null) {
            throw new ArgumentNullException("viewContext");
        }

        ViewContext = viewContext;
    }

    public ViewContext ViewContext
    {
        get;
        private set;
    }
}

Answer 2

You can do this very easily with an extension method (now available in .Net 3.5) Consider a class like this:

public static class ViewPageExtensions
{
    public static string DoSomething(this ViewPage page, string input)
    {
        // Do something clever with the page
    }
}

As long as your ViewPageExtensions class is visible to the namespaces you've imported on your ViewPage.aspx that you are working on, you should be able to access the DoSomething method directly, without referring to the ViewPageExtensions class.