Question

我将Code First与Entity Framework 5一起使用。

我有User课程，其中一个用户可以成为很多人的朋友。

public class User
{
    [Key]
    public Guid UserID { get; set; }
    public virtual ICollection<User> Friends { get; set; }
}

但这会映射0..1对多。我应该如何在Code First中与同一个类映射多对多关系？

Answer 1

添加配置类：

public class UserConfiguration : EntityTypeConfiguration<User>
{
    public UserConfiguration()
    {
        HasMany(u => u.Friends).WithMany();
    }
}

然后，这需要添加到上下文类

public class MyContext : DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new UserConfiguration());
        base.OnModelCreating(modelBuilder);
    }
}

Answer 2

public class Organization : Entity
{
    public string Name { get; set; }

    public string Description { get; set; }

    public virtual Organization Parent { get; set; }

    public virtual ICollection<Organization> Children { get; set; }

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

public class OrganizationConfiguration : EntityMapperBase<Organization>
{
    public OrganizationConfiguration()
    {
        HasKey(f => f.Id);
        Property(f => f.Name).HasMaxLength(20).IsRequired();
        HasMany(f => f.Children).WithOptional(f => f.Parent).Map(m => m.MapKey("ParentId")).WillCascadeOnDelete(false);
        HasMany(f => f.Users).WithRequired(f => f.Organization).Map(m => m.MapKey("OrganizationId"));
    }
}

可能对你有所帮助

Answer 3

你应该有两个导航属性

public class User
{
    [Key]
    public Guid UserID { get; set; }
    public virtual ICollection<User> FriendsOfMine { get; set; }
    public virtual ICollection<User> FriendsWithMe { get; set; }
}

如何使用Code First将多对多映射到同一个类？

3 个答案: