Using Extension Methods in ASP.NET MVC

Question

I am new to ASP.NET MVC. I have inherited a code base that I am trying to work with. I have a need to add some basic HTML attributes. Currently, in my .cshtml file, there is a block like this:

@Html.DropDown(model => model.SomeValue, Model.SomeList)

This references a function in Extensions.cs. This function looks like the following:

public static MvcHtmlString DropDown<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, IEnumerable<string> items, string classes = "form-control")
{
  var attributes = new Dictionary<string, object>();
  attributes.Add("class", classes);

  return System.Web.Mvc.Html.SelectExtensions.DropDownListFor(html, expression, itemList.Select(x => new SelectListItem() { Text = x.ToString(), Value = x.ToString() }), null, attributes);
}

I now have a case where I need to disable the drop down in some scenarios. I need to evaluate the value of Model.IsUnknown (which is a bool) to determine whether or not the drop down list should be enabled or not.

My question is, how do I disable a drop down list if I need to? At this point, I do not know if I need to update my .cshtml or the extension method.

Thank you for any guidance you can provide.

Ehsan Sajjad · Accepted Answer · 2015-02-19 16:11:12Z

6

Add an optional parameter in your extension method for disabling named enabledand bydefaut it will be true and from view pass bool parameter to disable or enable it:

public static MvcHtmlString DropDown<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, IEnumerable<string> items, string classes = "form-control",bool enabled=true)
{
  var attributes = new Dictionary<string, object>();
  attributes.Add("class", classes);
  if(!enabled)
     attributes.Add("disabled","disabled");

  return System.Web.Mvc.Html.SelectExtensions.DropDownListFor(html, expression, itemList.Select(x => new SelectListItem() { Text = x.ToString(), Value = x.ToString() }), null, attributes);
}

and now in View:

@Html.DropDown(model => model.SomeValue, Model.SomeList,enabled:false)

edited Feb 19, 2015 at 16:11

answered Feb 19, 2015 at 16:05

Ehsan Sajjad

62.6k16 gold badges112 silver badges171 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Using Extension Methods in ASP.NET MVC

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related