在EF4代碼中創建多對多關係代碼優先

Question

我正在使用EF4 Code-First進行建模，從事ASP.NET MVC中的項目工作。我有以下的模型類：

public class ComicBook 
{ 
    public long ComicBookID { get; set; } 
    public string IssueTitle { get; set; } 
    public int IssueNumber { get; set; } 
    public DateTime PublishDate { get; set; } 

    public IList<ComicBookPerson> Writers { get; set; } 
    public IList<ComicBookPerson> Pencillers { get; set; } 

    public IList<User> CollectingUsers { get; set; } 
} 

public class ComicBookPerson 
{ 
    public long ComicBookPersonID { get; set; } 
    public string Name { get; set; } 

    public IList<ComicBook> WorkedOnComicBooks { get; set; } 
} 

public class User 
{ 
    [Key] 
    public long UserID { get; set; } 
    public string Email { get; set; } 

    public IList<ComicBook> CollectedBooks { get; set; } 
} 

而下面的DbContext：

public class ComicContext : DbContext 
{ 
    public DbSet<ComicBook> ComicBooks { get; set; } 
    public DbSet<ComicBookPerson> ComicBookPerson { get; set; } 
    public DbSet<User> Users { get; set; } 

    protected override void OnModelCreating(DbModelBuilder modelBuilder) 
    { 
     modelBuilder.Entity<ComicBook>() 
      .HasMany(b => b.Writers) 
      .WithMany(w => w.WorkedOnComicBooks) 
      .Map(t => t.MapLeftKey("ComicBookID") 
       .MapRightKey("WriterID") 
       .ToTable("ComicBook_Writers")); 

     modelBuilder.Entity<ComicBook>() 
      .HasMany(b => b.Pencillers) 
      .WithMany(p => p.WorkedOnComicBooks) 
      .Map(t => t.MapLeftKey("ComicBookID") 
       .MapRightKey("PencillerID") 
       .ToTable("ComicBook_Penciller")); 
    } 
} 

的規則，需要應用有：

• 用戶可以有很多ComicBooks他們收集
• 漫畫書可以在衆多用戶的收藏中
• 每個漫畫書都可以有1個或多個作家
• 每個ComicBook可以有1個或多個Pencillers
• 一個ComicBookPerson可以在任何一本書
• 一個ComicBookPerson可以在很多書工作作家或Penciller，作爲一個作家，Penciller，或兩者

用戶和ComicBooks之間的多對多模式創建得很好。這是多人對ComicBooks和ComicBookPersons之間正在打破。我得到的錯誤消息是：

Schema specified is not valid. Errors: 
(15,6) : error 0040: Type ComicBook_Writers is not defined in namespace Comics.Models (Alias=Self). 

我基本上想要兩個連接表，一個名爲ComicBook_Writers，一個名爲ComicBookPencillers。這兩個表將包含一個ComicBookID和一個ComicBookPersonID。 EF Code First有可能嗎？

Answer 1

您需要兩個與作家和鋼筆者有關的ComicBookPerson類的集合屬性。

public class ComicBookPerson 
{ 
    public long ComicBookPersonID { get; set; } 
    public string Name { get; set; } 

    public IList<ComicBook> WroteComicBooks { get; set; } 
    public IList<ComicBook> PenciledComicBooks { get; set; } 
} 

模型映射爲

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    modelBuilder.Entity<ComicBook>() 
     .HasMany(b => b.Writers) 
     .WithMany(w => w.WroteComicBooks) 
     .Map(t => t.MapLeftKey("ComicBookID") 
      .MapRightKey("WriterID") 
      .ToTable("ComicBook_Writers")); 

    modelBuilder.Entity<ComicBook>() 
     .HasMany(b => b.Pencillers) 
     .WithMany(p => p.PenciledComicBooks) 
     .Map(t => t.MapLeftKey("ComicBookID") 
      .MapRightKey("PencillerID") 
      .ToTable("ComicBook_Penciller")); 
} 

Answer 2

我覺得這樣的模式接近是正確的，但仍然失去了一些東西。
的ComicBookPerson既可以是作家和penciller，這意味着你還需要第三列表在ComicBookPerson類：

public IList<ComicBook> WroteComicBooks { get; set; } 
public IList<ComicBook> PenciledComicBooks { get; set; } 
public IList<ComicBook> WrotPencComicBooks { get; set; } 

我說得對不對？