用于下拉菜单的自动映射IEnumerable <SelectListItem>

Question

问题

我目前正在为我的MVC项目添加自动化,而且我被卡住了.现在我有一个User模型用于表示数据库中的数据.我必须将该模型映射到EditUserModel,这将在调用Edit方法时使用.EditUserModel IEnumerable<SelectListItem>(对于下拉菜单)我似乎无法弄清楚如何映射.

试图解决方案

截至目前,我还没有尝试过任何事情.我不确定在哪里IEnumerable<SelectListItem>或哪里填充它的最佳位置.现在它正在控制器中填充.

User.cs

public class User
{
    [Key]
    public int UserID { get; set; }

    public string Username { get; set; }

    public string Password { get; set; }

    public int RoleID { get; set; }

    [ForeignKey("RoleID")]
    public virtual Role Role { get; set; }
}

EditUserModel.cs

public class EditUserViewModel
{
    [HiddenInput(DisplayValue = false)]
    public int UserID { get; set; }

    [Required]
    public String Username { get; set; }

    [Required]
    [DataType(DataType.Password)]
    public string Password { get; set; }

    [DisplayName("Role")]
    [Required]
    public int RoleID { get; set; }

    //The trouble field
    public IEnumerable<SelectListItem> Roles { get; set; }
}

Controller.cs

EditUserViewModel model = new EditUserViewModel();
//Population of the dropdown menu
model.Roles = context.Roles
    .ToList()
    .Select(x => new SelectListItem
    {
        Text = x.Description,
        Value = x.RoleID.ToString()
    });
//Mapping that the automaper will take care of
model.UserID = user.UserID;
model.Username = user.Username;
model.RoleID = user.RoleID;

Answer 1

为了记录,这是我在对Jakub的回答的评论中所说的:

public static class EnumerableExtensions
{
    public static IEnumerable<SelectListItem> ToSelectList<T, TTextProperty, TValueProperty>(this IEnumerable<T> instance, Func<T, TTextProperty> text, Func<T, TValueProperty> value, Func<T, bool> selectedItem = null)
    {
        return instance.Select(t => new SelectListItem
        {
            Text = Convert.ToString(text(t)),
            Value = Convert.ToString(value(t)),
            Selected = selectedItem != null ? selectedItem(t) : false
        });
    }
}

毋庸置疑,这是非常简单并且完成同样的事情(并且在属性路径不简单的情况下实际上更加健壮,因为Jakub的解决方案不适用于嵌套属性).

(这不是一个真正的答案,我将它作为社区维基发布,只是为了帮助阐述一点)