如何構建多對多關係的創建視圖

Question

好吧，看起來有人應該遇到這種情況，但我還沒有找到任何有用的東西。這是我的場景。

我有一個客戶和技能模型。其目標是讓客戶對每一套技能進行評分。

所以，在這裏，我將粘貼模型，視圖模型，控制器和視圖。在最後的關鍵問題

模型

namespace ClientSkills.Models 
{ 
public class Client 
{ 
    public int ClientId { get; set; } 
    public string Name { get; set; } 

    public ICollection<ClientSkills> Skills { get; set; } 

} 

public class Skill 
{ 
    public int SkillId { get; set; } 
    public string Name { get; set; } 

    public ICollection<ClientSkills> Clients { get; set; } 
} 

public class Rating 
{ 
    public int RatingId { get; set; } 
    public string Name { get; set; } 

    public ICollection<ClientSkills> ClientSkills { get; set; } 

} 

public class ClientSkills 
{ 
    [Key, Column(Order=0)] 
    public int ClientId { get; set; } 

    [Key, Column(Order = 1)] 
    public int SkillId { get; set; } 
    public int RatingId { get; set; } 

    public Rating Rating { get; set; } 
    public Skill Skill { get; set; } 
    public Client Client { get; set; } 
} 

public partial class ApplicationDbContext : IdentityDbContext<ApplicationUser> 
{ 
    public DbSet<Client> Client { get; set; } 
    public DbSet<Skill> Skill { get; set; } 
    public DbSet<Rating> Rating { get; set; } 
    public DbSet<ClientSkills> ClientSkills { get; set; } 

} 

} 

視圖模型

namespace ClientSkills.Models 
{ 
public class RateViewModel 
{ 
    public RateViewModel() 
    { 
     this.Skills = new List<SkillViewModel>(); 
    } 

    public RateViewModel(Client client) 
    { 
     this.ClientId = client.ClientId; 
     this.Skills = new List<SkillViewModel>(); 
     if (client.Skills.Count == 0) 
     { 
      var context = new ApplicationDbContext(); 
      foreach (var skill in context.Skill) 
      { 
       var skillVM = new SkillViewModel(skill); 
       skillVM.SelectedRatingid = context.Rating.First(r => r.Name == "No aplica").RatingId; 
       Skills.Add(skillVM); 
      } 
     } 
     else 
     { 
      foreach (var item in client.Skills) 
      { 
       var skillVM = new SkillViewModel(item); 
       skillVM.SelectedRatingid = item.SkillId; 
       this.Skills.Add(skillVM); 
      } 
     } 
    } 

    public int ClientId { get; set; } 

    public List<SkillViewModel> Skills { get; set; } 

} 

public class SkillViewModel 
{ 

    public SkillViewModel() 
    { 
     Ratings = new List<Rating>(); 
    } 
    public SkillViewModel(Skill skill) 
    { 
     var context = new ApplicationDbContext(); 
     this.Ratings = context.Rating.ToList(); 
     this.SkillId = skill.SkillId; 
     this.SkillName = skill.Name; 
    } 

    public SkillViewModel(ClientSkills item) 
    { 
     var context = new ApplicationDbContext(); 
     this.Ratings = context.Rating.ToList(); 
     this.SkillId = item.SkillId; 
     this.SkillName = item.Skill.Name; 
     this.SelectedRatingid = item.RatingId; 
    } 
    public List<Rating> Ratings { get; set; } 
    public int SelectedRatingid { get; set; } 
    public int SkillId { get; set; } 
    public string SkillName { get; set; } 

} 
} 

控制器

namespace ClientSkills.Controllers 
{ 
public class RateController : Controller 
{ 
    // 
    // GET: /Rate/Create 
    public ActionResult Create() 
    { 
     //first, we assume there is an already selected user 
     var context = new ApplicationDbContext(); 

     var client = context 
      .Client 
      .Include(c => c.Skills) 
      .First(c => c.Name.ToLower() == "ricker"); 
     var model = new RateViewModel(client); 
     return View(model); 
    } 
} 
} 

VIEW

此視圖是由創建與嚮導創建視圖，刪除它創建的無用場，並把下面

<table> 
     <tr> 
      <td>Skill</td> 
      <td>Rate</td> 
     </tr> 
     @foreach (var item in Model.Skills) 
     { 
      <tr> 
       <td> 
        @Html.DisplayFor(model => model.Skills.First(i => i.SkillName == item.SkillName).SkillName, new { @class = "control-label col-md-2" }) 
       </td> 
       <td> 
        @Html.DropDownListFor(x => item.SelectedRatingid, new SelectList(item.Ratings, "RatingId", "Name"), "Seleccione el valor") 
       </td> 
      </tr> 
     } 
</table> 

問題的代碼是在該行skillVM.SelectedRatingid = context.Rating.First(r => r.Name == "No aplica").RatingId;我的RateViewModel(Client client)構造爲selectedRatingId屬性設置默認值。我需要確保所有客戶都具備所有技能，即使他們忘記或繞過其中一個。

加載視圖時，我確信ratesid已設置好，技能名稱看起來不錯，但drop dpwn列表不顯示選定的默認值。

如何使視圖將selectedRatingId屬性綁定到下拉列表控件？

Answer 1

傳遞選定的值到的SelectList：

@Html.DropDownListFor(x => item.SelectedRatingid, new SelectList(item.Ratings, "RatingId", "Name", item.SelectedRatingid), "Seleccione el valor") 

據我所知（正確或錯誤），該最後一個參數是一個對象，如果它與選擇值中的一個相匹配 - 這是選擇其他的第一個中選項被選中。

有關Selectlist過載的更多信息。