Automapper映射的IEnumerable＆LT; SelectListItem＆GT;对于下拉菜单 [英] Automapper Mapping IEnumerable<SelectListItem> for Dropdown Menu

问题描述

问题

我目前将自动映射到我的MVC项目，我卡住了。现在我已经用在数据库中重新present数据的用户模型。我有该模型映射到时编辑方法被称为将用于一个EditUserModel。该EditUserModel有的IEnumerable＆LT; SelectListItem方式＆gt; （对于下拉菜单），我似乎无法弄清楚如何映射

尝试性解决方案

截至目前我还没有尝试过实施什么。我不确定其中用于最好的地方了IEnumerable＆LT; SelectListItem＆GT; 或者填充它。现在它正在被填充在控制器中。

User.cs

 公共类用户
{
    [键]
    公众诠释用户名{搞定;组; }    公共字符串用户名{获得;组; }    公共字符串密码{搞定;组; }    公众诠释角色ID {搞定;组; }    [ForeignKey的（角色ID）]
    公共虚拟角色角色{搞定;组; }
}
 

EditUserModel.cs

 公共类EditUserViewModel
{
    [HiddenInput（DisplayValue = FALSE）]
    公众诠释用户名{搞定;组; }    [需要]
    公共字符串用户名{搞定;组; }    [需要]
    [数据类型（DataType.Password）
    公共字符串密码{搞定;组; }    [显示名称（角色）]
    [需要]
    公众诠释角色ID {搞定;组; }    //麻烦场
    公共IEnumerable的＆LT; SelectListItem＆GT;角色{搞定;组; }
}
 

Controller.cs

  EditUserViewModel模式=新EditUserViewModel（）;
下拉菜单中的人口//
model.Roles = context.Roles
    .ToList（）
    。选择（X =＆gt;新建SelectListItem
    {
        文= x.Description，
        值= x.RoleID.ToString（）
    }）;
//映射的automaper会照顾
model.UserID = user.UserID;
model.Username = user.Username;
model.RoleID = user.RoleID;
 

解决方案

有关的记载，这里是我在评论中谈论到的Jakub的回答是：

 公共静态类EnumerableExtensions
{
    公共静态的IEnumerable＆LT; SelectListItem＆GT; ToSelectList＆LT; T，TTextProperty，TValueProperty＆GT;（这个IEnumerable的＆LT; T＆GT;例如，函数功能＆LT; T，TTextProperty＆gt;文字，Func键＆LT; T，TValueProperty＆GT;的价值，Func键＆LT; T，BOOL＆GT;将selectedItem = NULL）
    {
        返回instance.Select（T =＆gt;新建SelectListItem
        {
            文字= Convert.ToString（文字（T）），
            值= Convert.ToString（值（t））的
            选择=将selectedItem！= NULL？将selectedItem（T）：假
        }）;
    }
}
 

不用说，这是显着地更简单和完成同样的事情（实际上是在事件更健壮的属性路径是非简单，因为的Jakub的溶液不会与嵌套属性工作）。

（这是不是一个真正的答案，我张贴它作为一个社区维基只是帮助制定一个点）

Problem

I am currently adding automapping to my MVC project and I am stuck. Right now I have a User model used to represent data in the database. I have to map that model to a EditUserModel which will be used when the Edit method is called. The EditUserModel has IEnumerable<SelectListItem> (for a dropdown menu) that I can't seem to figure out how to map.

Attempted Solution

As of right now I haven't tried to implement anything. I am unsure where the best place for the IEnumerable<SelectListItem> or where to populate it. Right now it is being populated in the Controller.

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;

解决方案

For the record, here is what I was talking about in the comments to Jakub's answer:

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
        });
    }
}

Needless to say, this is dramatically simpler and accomplishes the same thing (and is actually more robust in the event that the property paths are non-simple, since Jakub's solution will not work with nested properties).

(This is not really an answer, I'm posting it as a community wiki just to help elaborate a point)

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