c# - C#模型用户，使用 Entity Framework 代码的好友请求和好友

我之前曾在此处就类似主题问过一个问题，但此后采取了不同的方法。这是我的模型：

public class ApplicationUser : IdentityUser<int, CustomUserLogin, CustomUserRole,CustomUserClaim>
{
    public ApplicationUser()
    {
        Friends = new List<Friend>();
    }

    [Required]
    public string Alias { get; set; }

    public virtual ICollection<Friend> Friends { get; set; }
}

public class Friend
{
    public virtual int Id { get; set; }

    public virtual ApplicationUser RequestedBy { get; set; }

    public virtual ApplicationUser RequestedTo { get; set; }

    public DateTime? RequestTime { get; set; }

    public FriendRequestFlag FriendRequestFlag { get; set; }
}

public enum FriendRequestFlag
{
    None,
    Approved,
    Rejected,
    Blocked,
    Spam
};

我可以使用这种方法添加好友，当我从数据库中获取好友时，它们会填充，例如：

public void AddFriendRequest(ApplicationUser user, ApplicationUser friendUser)
{
    var friendRequest = new Friend()
    {
        RequestedBy = user,
        RequestedTo = friendUser,
        RequestTime = DateTime.Now,
        FriendRequestFlag = FriendRequestFlag.None
    };

    user.Friends.Add(friendRequest);
}

当我运行上面的代码时，执行后数据库中的好友表如下所示：



当我获得一个用户时，如果该用户是RequestedBy或RequestedTo，我将不会使用实体框架获取Friend中的所有行。这与EF有关吗？例如使用Fluent API？我还想映射键，以便不需要[ApplicationUser_Id]。

最佳答案

@Mukesh感谢您的回答，但我决定采用另一种方法，因为您的解决方案未将Friend中的所有行都作为用户是RequestedBy还是RequestedTo。这是我的解决方案：

public class ApplicationUser : IdentityUser<int, CustomUserLogin, CustomUserRole,
CustomUserClaim>
{
    public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser, int> manager, string authenticationType)
    {
        // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
        var userIdentity = await manager.CreateIdentityAsync(this, authenticationType);
        // Add custom user claims here
        return userIdentity;
    }

    public ApplicationUser()
    {
        SentFriendRequests = new List<Friend>();
        ReceievedFriendRequests = new List<Friend>();
    }

    [Required]
    public string Alias { get; set; }

    public string Name { get; set; }

    public byte[] ProfilePicture { get; set; }

    public virtual ICollection<Friend> SentFriendRequests { get; set; }

    public virtual ICollection<Friend> ReceievedFriendRequests { get; set; }

    [NotMapped]
    public virtual ICollection<Friend> Friends {
        get
        {
            var friends = SentFriendRequests.Where(x => x.Approved).ToList();
            friends.AddRange(ReceievedFriendRequests.Where(x => x.Approved));
            return friends;
        } }
}

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

    modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
    modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();

    modelBuilder.Entity<Friend>()
        .HasRequired(a => a.RequestedBy)
        .WithMany(b => b.SentFriendRequests)
        .HasForeignKey(c => c.RequestedById);

    modelBuilder.Entity<Friend>()
        .HasRequired(a => a.RequestedTo)
        .WithMany(b => b.ReceievedFriendRequests)
        .HasForeignKey(c => c.RequestedToId);
}

public class Friend
{
    [Key, Column(Order = 0)]
    public int RequestedById { get; set; }
    [Key, Column(Order = 1)]
    public int RequestedToId { get; set; }
    public virtual ApplicationUser RequestedBy { get; set; }
    public virtual ApplicationUser RequestedTo { get; set; }

    public DateTime? RequestTime { get; set; }

    public DateTime? BecameFriendsTime { get; set; }

    public FriendRequestFlag FriendRequestFlag { get; set; }

    [NotMapped]
    public bool Approved => FriendRequestFlag == FriendRequestFlag.Approved;

    public void AddFriendRequest(ApplicationUser user, ApplicationUser friendUser)
    {
        var friendRequest = new Friend()
        {
            RequestedBy = user,
            RequestedTo = friendUser,
            RequestTime = DateTime.Now,
            FriendRequestFlag = FriendRequestFlag.None
        };
        user.SentFriendRequests.Add(friendRequest);
    }
}

public enum FriendRequestFlag
{
    None,
    Approved,
    Rejected,
    Blocked,
    Spam
};

关于c# - C#模型用户，使用 Entity Framework 代码的好友请求和好友，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/38999351/