使用Fluent爲實體框架設置遞歸映射4.1

Question

如何爲此類型設置流暢映射？

public class Topic 
{ 
    public int Id { get; set; }  
    public string Title { get; set; }  
    public virtual ICollection<Topic> Children { get; set; }  
    public int ParentId { get; set; }  
    public Topic Parent { get; set; }  
    public virtual ICollection<Topic> Related { get; set; } 
} 

Answer 1

我假設ParentId不是必需的，因爲不是每個主題都會有父項。

public class Topic 
{ 
    public int Id { get; set; } 
    public string Title { get; set; } 
    public int? ParentId { get; set; } 
    public Topic Parent { get; set; } 
    public virtual ICollection<Topic> Children { get; set; } 
    public virtual ICollection<Topic> Related { get; set; } 
} 

則映射將類似於東西

public class TopicMap : EntityTypeConfiguration<Topic> 
{ 
    public TopicMap() 
    { 
     HasKey(t => t.Id); 

     Property(t => t.Title) 
      .IsRequired() 
      .HasMaxLength(42); 

     ToTable("Topic"); 
     Property(t => t.Id).HasColumnName("Id"); 
     Property(t => t.Title).HasColumnName("Title"); 
     Property(t => t.ParentId).HasColumnName("ParentId"); 

     // Relationships 
     HasOptional(t => t.Parent) 
      .WithMany() 
      .HasForeignKey(d => d.ParentId); 
     //Topic might have a parent, where if it does, has a foreign key 
     //relationship to ParentId 
    } 
} 

和插件的型號綁定：

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    modelBuilder.Configurations.Add(new TopicMap()); 
    //modelBuilder.Configurations.Add(new TopicChildrenMap()); ..etc 
    //modelBuilder.Configurations.Add(new TopicRelatedMap()); ..etc 
} 

我也建議你的手在the EF Power Tools CTP。這對學習和理解如何創建流暢的配置非常有幫助。

希望有所幫助。