如何在asp.net mvc中为html.DropDownList设置值？

Question

how to set a value for the html.dropdownlist in asp.net mvc for example, suppose that we have this list

 @Html.DropDownList("Suppliers", Model.PDTO.ProjectSuppliers, new { @class = "text_field multiList hide", @multiple = "multiple" })*@

I know that I can use ListBoxFor or DropDownListFor Like this

@Html.ListBoxFor(model => model.Suppliers, Model.PDTO.ProjectSuppliers, new { @class = "text_field multiList hide", @multiple = "multiple" })

but I am wondering about how can we do this with the DropDownList, I tried to search in google but I found answers just for DropDownListFor .

Any help please.

Answer 1

DropDownList is not strongly typed. To get selected options for DropDownList you should write code in your action.

The following code snippet may help you.

In your action:

var selectedValue = new List<int> {1, 2};
ViewBag.ProjectSuppliers= new MultiSelectList(SupplierList, "Id", "SupplierName", selectedValue );

In you view:

@Html.DropDownList("Suppliers", (MultiSelectList)ViewBag.ProjectSuppliers, "-----Select-----", new { multiple="" })

Answer 2

Not sure if this is what you mean, but I know I've used dropdownlist before by loading up an

IEnumerable<SelectListItems> selectList

in the controller, passing it to the ViewBag

ViewBag.selectList = selectList;

and then just using

@Html.DropDownList("selectList") 

in the view.

There are overloads for it if you choose to go another route though. https://msdn.microsoft.com/en-us/library/system.web.mvc.html.selectextensions.dropdownlist(v=vs.118).aspx

See the following for a more detailed example of the ViewBag method: http://www.mikesdotnetting.com/article/128/get-the-drop-on-asp-net-mvc-dropdownlists

Answer 3

We will have to assign data to dropdownlist from ViewData then we will able to set selected value to dropdownlist, something like this below

private ActionResult GetEmployeesForDropDown()
{
    var lstEmployees = new[] 
    {   
        new Employee { Id = 1, Name = "Emp1" }, 
        new Employee { Id = 2, Name = "Emp2" }, 
        new Employee { Id = 3, Name = "Emp3" } 
    };
    var selectList = new SelectList(lstEmployees, "Id", "Name", 0);  
    //Here 0 is the selectedIndex which we are assigning to dropdownlist, we can pass value we want here to set the index
    ViewData["Employees"] = selectList;  
    // dropdownlist datasource which is a employeelist is assigned to a ViewData here
    return View();
}

View will look like this

@Html.DropDownList("ddEmployees", (SelectList)ViewData["Employees"], "---Select---", new {@class="DropDownCssIfAny"})

Answer 4

Controller:

List<Department> departments = dbHR.Departments.OrderBy(d => d.DEPARTMENT_NAME).ToList();
departmentsList = new SelectList(departments, "DEPARTMENT_ID", "DEPARTMENT_NAME", deptInt);
 ViewBag.DepartmentsList = departmentsList;

View:

<%: Html.DropDownList("DEPARTMENTS", (IEnumerable<SelectListItem>)ViewBag.DepartmentsList, string.Empty)%>