c# - MVC 4 Simple Populate DropDown 从数据库模型

Question

我觉得有点傻。

我试图掌握 MVC 4 的窍门，使用装箱作为功能示例。

我在数据库中有 WeightCategories(Heavyweights 等)和 Boxers。

看似简单。关系是一个拳击手有一个当前的体重类别，但当我编辑时，我希望它能够通过下拉菜单改变它。

如果它是我自己在代码中制作的列表，我知道该怎么做，但我无法理解如何从 WeightCategory 表中“加载”列表并将其显示在拳击手的 View /模型。

所以，这是我为 WeightCategory 项目编写的代码:

[Table("WeightCategories")]
public class WeightCategory
{
    [Key]
    public int WeightCategoryId { get; set; }

    public WEIGHT_CATEGORIES WeightCategoryType { get; set; }

    [Display(Name = "Weight Category Name")]
    [Required]
    [MinLength(5)]
    public string Name { get; set; }
    [Display(Name = "Weight Limit In Pounds")]        
    public int? WeightLimit { get; set; }
}

这是拳击手项目的代码

[Table("Boxers")]
public class Boxer
{
    [Key]
    public int BoxerId { get; set; }

    public WeightCategory CurrentWeightCategory { get; set; }

    [Required]
    public string Name { get; set; }
    public int Wins { get; set; }
    public int Losses { get; set; }
    public int Draws { get; set; }
    public int Kayos { get; set; }
}

在 View 中，我真的不确定如何解决这个问题，我很确定它不是自动的，我可能需要将表加载到 Controller 中的某个位置......我正在寻找最佳实践或其他东西.

最后的 View 中类似的东西:

@Html.DropDownListFor(model => model.CurrentWeightCategory.WeightCategoryId,
                      new SelectList(Model.WeightCategories, "WeightCategoryId", "Name", 
                                     Model.WeightCategories.First().WeightCategoryId))

Answer 1

你可以设计一个 View 模型:

public class MyViewModel
{
    public Boxer Boxer { get; set; }
    public IEnumerable<SelectListItem> WeightCategories { get; set; }
}

然后让您的 Controller 操作填充并将此 View 模型传递给 View :

public ActionResult Edit(int id)
{
    var model = new MyViewModel();
    using (var db = new SomeDataContext())
    {
        // Get the boxer you would like to edit from the database
        model.Boxer = db.Boxers.Single(x => x.BoxerId == id);

        // Here you are selecting all the available weight categroies
        // from the database and projecting them to the IEnumerable<SelectListItem>
        model.WeightCategories = db.WeightCategories.ToList().Select(x => new SelectListItem
        {
            Value = x.WeightCategoryId.ToString(),
            Text = x.Name
        })
    }
    return View(model);
}

现在你的 View 变成了 View 模型的强类型:

@model MyViewModel
@Html.DropDownListFor(
    x => model.Boxer.CurrentWeightCategory.WeightCategoryId,
    Model.WeightCategories
)