Question

i start to study mvc, try to add dropdownlist, make construction

<%= Html.DropDownList("ddl") %>

but it show error

There is no ViewData item of type ‘IEnumerable’ that has the key ‘ddl’

why? i use simple code, only pass name parameter, so why the error?

Answer 1

"There is no ViewData item of type 'IEnumerable'"

It means that helper method is expecting an item of type 'IEnumerable' for e.g, List<> with an Id 'ddl'

If you are trying to display a DropDownList which has items from some static source, here is one way to do this.

          // create new IEnummerable 
          List<string> ddl = 
          new List<string>(new [] {"item1","item2" };   

          // add Items        
          ddl.Add("Item1");
          ddl.Add("Item2");

          // return View which holds ddl now
          ViewData["ddl "] = ddl ;
          return View();

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For more insight have a look at

• Understanding HTML Helpers
• How to create a DropDownList with
  ASP.NET MVC