實體框架許多一對多

public class Project 
{ 


    public virtual int ID { get; set; } 

    [Required] 
    public virtual String Title { get; set; } 


    public String Definition { get; set; } 
    public DateTime StartDate { get; set; } 


    [Required] 
    public int CreaterID { get; set; } 

    public virtual ICollection<Status> Status { get; set; } 
    public virtual ICollection<Task> Tasks { get; set; } 
    public virtual ICollection<User> Users { get; set; } 

    public Project() 
    { 
     Users = new HashSet<User>(); 
    } 


} 


public class User 
{ 
    public int ID { get; set; } 


    [DisplayName("Kullanıcı Adı")] 
    [Required] 
    [MinLength(5, ErrorMessage = "Kullanıcı Adı En Az 5 Karakter Olmalıdır")] 
    public string username { get; set; } 

    [DataType(DataType.Password)] 
    [DisplayName("Şifre")]   
    [Required] 
    [MinLength(3,ErrorMessage="Şifre En Az 3 Karakter Olmalıdır")] 
    public string password { get; set; } 

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

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

    public int? CreaterID { get; set; } 
    public int level { get; set; } 

    public ICollection<Task> Tasks { get; set; } 
    public ICollection<Project> Projects { get; set; } 

    public User() 
    { 
     Projects = new HashSet<Project>(); 
    } 
} 


public class TaskDB : DbContext 
{ 
    public DbSet<Comment> Comments { get; set; } 
    public DbSet<Project> Projects { get; set; } 
    public DbSet<Situation> Situaitons { get; set; } 
    public DbSet<Task> Tasks { get; set; } 
    public DbSet<User> Users { get; set; } 

    protected override void OnModelCreating(DbModelBuilder modelBuilder) 
    { 
     modelBuilder.Entity<Project>(). 
      HasMany(c => c.Users). 
      WithMany(p => p.Projects). 
      Map(
      m => 
      { 
       m.MapLeftKey("ProjectId"); 
       m.MapRightKey("UserId"); 
       m.ToTable("ProjectUser"); 
      }); 
    } 

}

如果我添加項目，當前用戶添加到項目的用戶列表中，但不會添加當前用戶的項目列表這是我的項目添加代碼項目實體框架許多一對多

[HttpPost] 
    public ActionResult Create(Project proje,Status status) 
    { 

     proje.StartDate = DateTime.Now; 
     proje.Status = new HashSet<Status>(); 
     var user = _db.Users.Single(r=> r.ID == UserRole.ID); 
     proje.Users.Add(user); 
     proje.Status.Add(status); 
     user.Projects.Add(proje); 


     if (ModelState.IsValid) 
     { 
      var projeler = _db.Projects; 
      projeler.Add(proje); 
      _db.SaveChanges(); 

      return RedirectToAction("Index"); 

     } 


      return View(proje); 

    }

我搜索此問題的原因我沒有找到，我想了解爲什麼實體框架將用戶添加到項目的列表中，但不會將項目添加到用戶的列表中

來源

2012-10-20 bluenesman

將您的新項目添加到數據庫的代碼看起來是正確的，並且關係最有可能存儲。

但是可能您不會加載Projects列表User。如果你打電話......

var project = _db.Projects.Single(p => p.ID == 1); 
var users = project.Users; // lazy loading because Users is virtual

...你會看到該項目的用戶，因爲他們得到延遲加載因爲Project.Users屬性標記爲virtual。如果你做同樣的用User ......

var user = _db.Users.Single(u => u.ID == 1); 
var projects = user.Projects; // no lazy loading because Projects is not virtual

...的項目沒有得到加載，因爲User.Projects屬性沒有標記爲virtual。

要麼標記財產virtual以及啓用延遲加載的User.Projects集合：

public virtual ICollection<Project> Projects { get; set; }

或者使用預先加載：

var user = _db.Users.Include(u => u.Projects).Single(u => u.ID == 1);

來源

2012-10-20 15:48:41 Slauma

實體框架許多一對多

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