使用 select2 向 DropDownListFor 添加空值

Question

我想显式添加一个空值，以便我可以将其用于 jQuery。

$('#empId').select2({
    placeholder: "Select report type",
    allowClear: true,
    width: "265px"
});

如何让它显示为 select 的第一个（空）选项？

代码：

 @Html.DropDownListFor(m => m.EmpNameSelected,
    new SelectList(Model.ListOfEmployee, "", "", Model.EmpNameSelected),
     Model.EmpNameSelected, new { id = "empId" })

Answer 1

假设你有这个模型：

public class EmployeeModel
{
    public string EmpNameSelected { get; set; }
    public List<Employee> ListOfEmployee { get; set; }
}

public class Employee
{
    public int EmployeeId { get; set; }
    public string EmployeeName { get; set; }
}

这是控制器：

    public ActionResult TestEmployeeDropDownList()
    {
        var model = new EmployeeModel
        {
            ListOfEmployee = new List<Employee>
            {
                new Employee { EmployeeId = 1, EmployeeName = "John Doe" },
                new Employee { EmployeeId = 2, EmployeeName = "John Roe" },
                new Employee { EmployeeId = 3, EmployeeName = "Jane Doe" },
            }
        };
        return View(model);
    }

最后是视图：

@{
    var emptyEmployee = new MvcApplication.Models.Employee { EmployeeId = 0, EmployeeName = string.Empty };
    Model.ListOfEmployee.Insert(0, emptyEmployee);
}
@Html.DropDownListFor(m => m.EmpNameSelected, new SelectList(Model.ListOfEmployee, "EmployeeId", "EmployeeName", 0), new { id = "empId" })

Answer 2

希望这对其他人有帮助...

我真正需要的只是一行代码来插入一个新的 empty value

@{Model.ListOfEmployee.Insert(0, "");}  //insert empty value

@Html.DropDownListFor(m => m.EmpNameSelected,
    new SelectList(Model.ListOfEmployee, "", "", Model.EmpNameSelected),
     Model.EmpNameSelected, new { id = "empId" })

使用 select2 向 DropDownListFor 添加空值

Adding empty value to a DropDownListFor using select2

jquery

asp.net-mvc

razor

jquery-select2