由构造函数链接到数据模型的视图模型

Question

我没有任何其他方式来描述它，那么我是如何在标题中做到的。

我有一个看起来像这样的视图模型：

public class CreateArtistModel 
{   
    public IEnumerable<SelectListItem> Cultures { get; set; } 
    public IEnumerable<SelectListItem> Products { get; set; } 
    public Artists Artist { get; internal set; } 

    /// <summary> 
    /// Default constructor 
    /// </summary> 
    public CreateArtistModel() { } 

    /// <summary> 
    /// Non-default constructor with 1 parameter, culturelist 
    /// </summary> 
    /// <param name="cultures">List that can contain all the possible cultures.</param> 
    /// <param name="products">List that can contain all possible products.</param> 
    public CreateArtistModel(IEnumerable<SelectListItem> cultures, IEnumerable<SelectListItem> products) { Cultures = cultures; Products = products; } 

    /// <summary> 
    /// Non-default constructor that can have 1 parameter, artist 
    /// </summary> 
    /// <param name="artist">The artist with its various properties</param> 
    public CreateArtistModel(Artists artist) { Artist = artist; } 

    /// <summary> 
    /// Non-default constructor that can have 2 parameter, a list cultureList and an atist 
    /// </summary> 
    /// <param name="cultures">List that can contain all the possible cultures.</param> 
    /// <param name="products">List that can contain all possible products.</param> 
    /// <param name="artist">The artist with its various properties</param> 
    public CreateArtistModel(IEnumerable<SelectListItem> cultures, IEnumerable<SelectListItem> products, Artists artist) 
    { 
     Cultures = cultures; 
     Products = products; 
     Artist = artist; 
    } 

    [Required(ErrorMessage = "The artist's first name is required")] 
    public string firstname { get; set; } 

    [Required(ErrorMessage = "The artist's last name is required")] 
    public string lastname { get; set; } 

    public Nullable<int> dateOfBirth { get; set; } 

    public Nullable<int> dateOfDeath { get; set; } 

    [Required(ErrorMessage = "The artist's speciality is required")] 
    public string speciality { get; set; } 

    public string placeOfBirth { get; set; } 
} 

我的看法则使用性质是这样的：

@model ArtWebShop.Areas.Admin.Models.CreateArtistModel 

@Html.EditorFor(model => model.firstname) 
@Html.ValidationMessageFor(model => model.firstname) 

然后在我的控制器，我保存它是这样的：

 [HttpPost] 
    public ActionResult Create(Artists artist) 
    { 
     if (!ModelState.IsValid) 
     { 
      return View(CreateArtistWithListOfProductsAndcultures(artist)); 
     } 

     if (_unitOfWork != null) 
     { 
      _unitOfWork.ArtistsRepository.Create(artist); 
      _unitOfWork.Save(); 
     } 
     return RedirectToAction("Index", "Overview", new { area = "Admin" }); 
    } 

而且工作！ 但我不知道为什么...

我想明白为什么这个工程。为什么我的视图模型中的属性自动链接到艺术家模型？

Answer 1

那么魔法是我的模型粘合剂。默认的ASP.Net modelbinder有能力通过表单发布数据和\或查询字符串重新创建操作参数。所以当POST发生时，Modelbinder会启动并检查发布数据的编码，并尝试为您的操作方法构建对象。它根据参数 - 属性名称匹配进行映射。

这也意味着Modelbinder确实关心您的Model或ViewModel类。只要它在操作参数中获取类类型，它就会尝试将POST（主体内容）或GET（查询字符串）参数映射到您的自定义类属性。您的ViewModel事实上只是在这里无关紧要，除了它有助于呈现HTML表单，并且INPUT元素的名称与模型属性相匹配。

你可以看看这些文章，以获得深入了解Modelbinders。

http://msdn.microsoft.com/en-us/magazine/hh781022.aspx

http://www.codeproject.com/Articles/159749/ASP-NET-MVC-Model-Binding-Part1

http://www.codeproject.com/Articles/161963/ASP-NET-MVC-Model-Binding-Part-2