向HTML.DropDownListFor添加一个类

Question

I am trying to add a class assignment to the following line of code,

        @Html.DropDownListFor(model => model.Business, new SelectList(
              new List<Object>{
                   new { ... },
                   new { ... },
                   new { ... }
                },
              "value",
              "text",
              2))

One answer given on this site ( HTML.DropDownListFor class assignment ) suggested adding it as an overload method that takes a 'object htmlAttributes' as the last parameter. However, I can not see this parameter as an option so I'm a bit confused how this is possible.

In my example I am using every overload method possible and there is none for htmlattributes.

Answer 1

Four of the DropDownListFor overloads have HTML Attributes as their last parameter. This one is probably the easiest. Modifying your example, it becomes:

@Html.DropDownListFor(model => model.Business, 
                      new SelectList(
                          new List<Object>{
                              new { ... },
                              new { ... },
                              new { ... }
                          },
                          "value",
                          "text",
                          2),
                      new {
                          @class = "myclass"
                      })

Answer 2

Use following overload:

public static MvcHtmlString DropDownListFor<TModel, TProperty>(
this HtmlHelper<TModel> htmlHelper,
Expression<Func<TModel, TProperty>> expression,
IEnumerable<SelectListItem> selectList,
IDictionary<string, Object> htmlAttributes
)

Here is MSDN docs of the overload

do this way:

@Html.DropDownListFor(model => model.Business, 
                      new SelectList(new List<Object>
                                 { 
                                  new { ... },
                                  new { ... },
                                  new { ... } 
                                }, 
                                "value", "text", 2),
                     new { @class ="YourClass"})

or following overload will also work:

public static MvcHtmlString DropDownListFor<TModel, TProperty>(
this HtmlHelper<TModel> htmlHelper,
Expression<Func<TModel, TProperty>> expression,
IEnumerable<SelectListItem> selectList,
string optionLabel,
IDictionary<string, Object> htmlAttributes
)

this way:

@Html.DropDownListFor(model => model.Business, 
                      new SelectList(new List<Object> 
                                        { 
                                         new { ... }, 
                                         new { ... },
                                        }, "value", "text", 2), 
                      null,new { @class ="YourClass"})

MSDN docs of the overload