c# - EF Code First：如何使用 fluent api 修复关系

Question

我有一个用 Enitity Framework 描述的简单数据模型，但仍然无法解决我的模型中的关系问题。我尝试了一些使用 Fluent API 的方法，但总是遇到非描述性异常。

这是一个代码：

public abstract class Entity
{
    [Key, Column(Order = 1)]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Int32 Id { get; set; }
}

public class Language : Entity
{
    [Key, Column(Order = 2)]
    public String Verbal { get; set; }

    public virtual ICollection<PostContent> Contents { get; set; }
}

public class Post : Entity
{
    public virtual ICollection<PostContent> Contents { get; set; }
}

public class PostContent
{
    [Key, Column(Order = 1)]
    public Int32 PostId { get; set; }

    [Key, Column(Order = 2)]
    public Int32 LanguageId { get; set; }

    [ForeignKey("PostId")]
    public virtual Post Post { get; set; }

    [ForeignKey("LanguageId")]
    public virtual Language Language { get; set; }

    public String Content { get; set; }
}

public class BlogContext : DbContext
{
    public DbSet<Language> Languages { get; set; }
    public DbSet<Post> Posts { get; set; }
    public DbSet<PostContent> PostContents { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }
}

public class BlogContextInitializer : DropCreateDatabaseIfModelChanges<BlogContext>
{
    protected override void Seed(BlogContext context)
    {
        //For test
        context.Languages.Add(new Language { Verbal = "Italian" });
        context.Languages.Add(new Language { Verbal = "English" });
        context.SaveChanges();
    }
}

class Program
{
    static void Main(string[] args)
    {
        Database.SetInitializer<BlogContext>(new BlogContextInitializer());

        using (BlogContext blogContext = new BlogContext())
        {
            //init on call.
            var langs = blogContext.Set<Language>().AsEnumerable();
            foreach (var lang in langs)
            {
                Console.WriteLine("Language Id: {0}, Verbal: {1}", lang.Id, lang.Verbal);
            }
        }
    }
}

我有：

“关系约束中的从属角色和主要角色中的属性数量必须相同。”

所以我正在寻找这个问题的解决方案。