实体框架代码优先映射

Question

我有两个类，Group 类与 User 类（代表用户所属的组）是多对多的关系，然后组与用户类（代表所有者）也有一对多的关系一组）。

如何映射？

public class User
{
    public int Id { get; set; }
    public string Avatar { get; set; }
    public string Name { get; set; }
    public string Message { get; set; }

    public virtual ICollection<Group> OwnedGroups { get; set; }
    public virtual ICollection<Group> Groups { get; set; }
}

public class Group
{
    public int Id { get; set; }
    public DateTime CreateDate { get; set; }
    public DateTime ModifyDate { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public bool System { get; set; }
    public int ViewPolicy { get; set; }
    public int JoinPolicy { get; set; }
    public string Avatar { get; set; }
    public int Order { get; set; }
    public int GroupType { get; set; }

    public virtual User Owner { get; set; }
    public virtual ICollection<User> Members { get; set; }
}

提前通知！

Answer 1

我会使用流畅的 API：

public class Context : DbContext
{
    public DbSet<User> Users { get; set; }
    public DbSet<Group> Groups { get; set; }

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

        modelBuilder.Entity<User>()
                    .HasMany(u => u.Groups)
                    .WithMany(g => g.Members);

        modelBuilder.Entity<User>()
                    .HasMany(u => u.OwnedGroups)
                    .WithRequired(g => g.Owner)
                    .WillCascadeOnDelete(false);
    }
}

数据注释也应该可以：

public class User
{
    ...

    [InverseProperty("Owner")]
    public virtual ICollection<Group> OwnedGroups { get; set; }
    [InverseProperty("Members")]
    public virtual ICollection<Group> Groups { get; set; }
}

public class Group
{
    ...

    [InverseProperty("OwnedGroups")]
    public virtual User Owner { get; set; }
    [InverseProperty("Groups")]
    public virtual ICollection<User> Members { get; set; }
}

InverseProperty 不需要在关系的两边，但它的定义更清晰。