Adding a css class to select using @Html.DropDownL

问题:

I'm building my first MVC application after years of doing webforms, and for some reason I am not able to make this work:

@Html.DropDownList("PriorityID", String.Empty, new {@class="textbox"} )

Error message:

System.Web.Mvc.HtmlHelper<SPDR.Models.Bug>' does not contain a definition for DropDownList and the best extension method overload System.Web.Mvc.Html.SelectExtensions.DropDownList(System.Web.Mvc.HtmlHelper, string, System.Collections.Generic.IEnumerable<System.Web.Mvc.SelectListItem>, object) has some invalid arguments

Any help greatly appreciated!

回答1:

Looking at the controller, and learing a bit more about how MVC actually works, I was able to make sense of this.

My view was one of the auto-generated ones, and contained this line of code:

@Html.DropDownList("PriorityID", string.Empty)

To add html attributes, I needed to do something like this:

@Html.DropDownList("PriorityID", (IEnumerable<SelectListItem>)ViewBag.PriorityID, new { @class="dropdown" })

Thanks again to @Laurent for your help, I realise the question wasn't as clear as it could have been...

UPDATE:

A better way of doing this would be to use DropDownListFor where possible, that way you don't rely on a magic string for the name attribute

@Html.DropDownListFor(x => x.PriorityID, (IEnumerable<SelectListItem>)ViewBag.PriorityID, new { @class = "dropdown" })

回答2:

As the signature from the error message implies, the second argument must be an IEnumerable, more specifically, an IEnumerable of SelectListItem. It is the list of choices. You can use the SelectList type, which is a IEnumerable of SelectListItem. For a list with no choices:

@Html.DropDownList("PriorityID", new List<SelectListItem>(), new {@class="textbox"} )

For a list with a few choices:

@Html.DropDownList(
    "PriorityID", 
    new List<SelectListItem> 
    { 
        new SelectListItem { Text = "High", Value = 1 }, 
        new SelectListItem { Text = "Low",  Value = 0 },
    }, 
    new {@class="textbox"})

Maybe this tutorial can be of help: How to create a DropDownList with ASP.NET MVC

回答3:

If you are add more than argument ya dropdownlist in Asp.Net MVC. When you Edit record or pass value in view bag.

Use this it will be work:-

@Html.DropDownList("CurrencyID",null,String.Empty, new { @class = "form-control-mandatory" })

回答4:

There are some options in constructors look, if you don't have dropdownList and you wanna insert CSS class you can use like

@Html.DropDownList("Country", null, "Choose-Category", new {@class="form-control"})

in this case Country is the name of your dropdown, null is for you aren't passing any generic list from your controller "Choose-Category" is selected item and last one in CSS class if you don't wanna select any default option so simple replace "Choose-Category" with ""

回答5:

You Can do it using jQuery

  $("select").addClass("form-control")

here, Select is- html tag, Form-control is- class name

 @Html.DropDownList("SupplierId", "Select Supplier")

and here, SupplierId is ViewBagList, Select Supplier is - Display Name

回答6:

Simply Try this

@Html.DropDownList("PriorityID", (IEnumerable<SelectListItem>)ViewBag.PriorityID,  new { @class="dropdown" })

But if you want a default value or no option value then you must have to try this one, because String.Empty will select that no value for you which will work as a -select- as default option

@Html.DropDownList("PriorityID", (IEnumerable<SelectListItem>)ViewBag.PriorityID, String.Empty, new { @class="dropdown" })

回答7:

Try below code:

@Html.DropDownList("ProductTypeID",null,"",new { @class = "form-control"})

回答8:

Try this:

@Html.DropDownList(
    "country", 
    new[] {
        new SelectListItem() { Value = "IN", Text = "India" },
        new SelectListItem() { Value = "US", Text = "United States" }
    }, 
    "Country",
    new { @class = "form-control",@selected = Model.Country}
)

回答9:

You can simply do this:

@Html.DropDownList("PriorityID", null, new { @class="form-control"})

回答10:

Try This

 @Html.DropDownList("Id", null, new { @class = "ct-js-select ct-select-lg" })