How can I use a HTML helper method in an extension method? - asp.net-mvc

Question

I have the following classes:
public class Note
{
public string Text { get; set; }
public RowInfo RowInfo { get; set; }
}
public class RowInfo
{
[DisplayName("Created")]
public DateTime Created { get; set; }
[DisplayName("Modified")]
public DateTime Modified { get; set; }
}
In my view I have the following which creates HTML with the correct name and value:
Html.HiddenFor(model => model.Note.Created)
Now what I am trying to do is to create an extension method that will include the above and that I can call in each view. I have tried doing the following. I think I am on the right track but I don't know how to do the equivalent of "model => model.Note.Created" Can someone give me some advice on how I can do this and what I would need to replace the text inside the parenthesis with. I don't have a model but I can do this some other way so the hidden field will go look at my class to get the correct DisplayName just like it does above?
namespace ST.WebUx.Helpers.Html
{
using System.Web.Mvc;
using System.Web.Mvc.Html
using System.Linq;
public static class StatusExtensions
{
public static MvcHtmlString StatusBox(this HtmlHelper helper, RowInfo RowInfo )
{
return new MvcHtmlString(
"Some things here ... " +
System.Web.Mvc.Html.InputExtensions.Hidden( for created field ) +
System.Web.Mvc.Html.InputExtensions.Hidden( for modified field ) );
}
}

Answer 1

You could write a strongly typed helper taking a λ-expression:
public static class StatusExtensions
{
public static IHtmlString StatusBox<TModel, TProperty>(
this HtmlHelper<TModel> helper,
Expression<Func<TModel, TProperty>> ex
)
{
return new HtmlString(
"Some things here ... " +
helper.HiddenFor(ex));
}
}
and then:
#Html.StatusBox(model => model.RowInfo.Created)
UPDATE:
As requested in the comments section here's a revised version of the helper:
public static class StatusExtensions
{
public static IHtmlString StatusBox<TModel>(
this HtmlHelper<TModel> helper,
Expression<Func<TModel, RowInfo>> ex
)
{
var createdEx =
Expression.Lambda<Func<TModel, DateTime>>(
Expression.Property(ex.Body, "Created"),
ex.Parameters
);
var modifiedEx =
Expression.Lambda<Func<TModel, DateTime>>(
Expression.Property(ex.Body, "Modified"),
ex.Parameters
);
return new HtmlString(
"Some things here ..." +
helper.HiddenFor(createdEx) +
helper.HiddenFor(modifiedEx)
);
}
}
and then:
#Html.StatusBox(model => model.RowInfo)
Needless to say that custom HTML helpers should be used to generate small portions of HTML. Complexity could grow quickly and in this case I would recommend you using an editor template for the RowInfo type.