将一个（实体类）映射到多个（dto's/viewModels）

Question

我正在尝试将有关用户的信息映射到几个 dto，但我得到了 null 异常。基本上，我将信息分布在几个类之间的原因是因为在几个视图中有我需要的公共信息。所以这就是我最终的结果：

用户实体类

public class User 
{
    public int Id { get; set; }
    public string Nickname { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
    public string Password { get; set; }
    public float Credits { get; set; }
    public float PromotionalCredits { get; set; }
    public string Telephone { get; set; }
    public string Mobile { get; set; }
    public double RatingAverage { get; set; }
    public string ProfileImage { get; set; } 
    public virtual ICollection<Address> Addresses { get; set; }
    public virtual ICollection<Role> Roles { get; set; }
    public virtual ICollection<Comment> Comments { get; set; }
    public virtual ICollection<Item> Items { get; set; }
    public virtual ICollection<Bid> Bids { get; set; }
    public virtual ICollection<CreditCard> CreditCard { get; set; }
    public virtual ICollection<Message> ReceivedMessages { get; set; }
    public virtual ICollection<Message> SentMessages { get; set; }
    public virtual ICollection<Item> WatchList { get; set; }
    public virtual ICollection<Rating> OwnRatings { get; set; }
    public virtual ICollection<Rating> RatingsForOthers { get; set; }
 }

DTO 和 ViewModel 类

public class UserInfoSummaryViewModel
{
    public int Id { get; set; }
    public string FullName { get; set; }
    public UserDetailedStatus DetailedStatus { get; set; }
}

public class UserDetailedStatus
{
    public float TotalCredits { get; set; }
    public float Credits { get; set; }
    public float PromotionalCredits { get; set; }
    public BiddingAndItems BiddingAndItems { get; set; }
    public int OngoingListings { get; set; }
    public int NewMessages { get; set; }
    public float Rating { get; set; }
    public int NumberOfRatings { get; set; }
}

public class BiddingAndItems
{
    public int TotalBids { get; set; }
    public int WinningBids { get; set; }
    public int AcquiredItems { get; set; }
    public int ItemsAwaitingConfirmation { get; set; }
    public List<ItemForUserBids> Items { get; set; }
}

AutoMapperBootStrapper 类中的映射

Mapper.CreateMap<User, BiddingAndItems>()
                .ForMember(m => m.TotalBids, o => o.MapFrom(s => s.TotalActiveBids()))
                .ForMember(m=>m.ItemsAwaitingConfirmation, o=>o.MapFrom(s=>s.Items.Count(i=>i.IsAwaitingReceptionConfirmation().Equals(true))))
                .ForMember(m=>m.AcquiredItems, o=>o.MapFrom(s=>s.AquiredItems().Count))
                .ForMember(m => m.WinningBids,
                           o => o.MapFrom(s => s.Bids.Where(c => c.Item.CurrentHighestBidderId().Equals(s.Id))));

            Mapper.CreateMap<User, UserDetailedStatus>()
                .ForMember(m => m.NumberOfRatings, o => o.MapFrom(s => s.OwnRatings.Count()))
                .ForMember(m => m.NewMessages, o => o.MapFrom(s => s.TotalUnreadMessages()))
                .ForMember(m => m.OngoingListings, o => o.MapFrom(s => s.Items.Where(i => i.IsPublished())))
                .ForMember(m => m.Rating, o => o.MapFrom(s => s.RatingAverage))
                .ForMember(m => m.TotalCredits, o => o.MapFrom(s => s.TotalCredits()));

            Mapper.CreateMap<User, UserInfoSummaryViewModel>();

调用 UserController 内的自动映射器

    public ActionResult Summary()
    {

        var user = _helper.GetUserFromSession();
        var viewModel = Mapper.Map<User, UserInfoSummaryViewModel>(user);
        return View(viewModel);
    }

我认为，因为我在引导程序中拥有所有必要的映射，所以 理论上应该可以工作，显然我错了......我该如何解决这个问题？

更新：

我修复了我的映射并添加了几个值解析器。现在我没有收到空引用异常，但似乎有问题，因为每次我运行项目时它都会卡住，然后本地服务器停止响应......这是我的代码：

        Mapper.CreateMap<User, BiddingAndItems>()
            .ForMember(m => m.TotalBids, o => o.MapFrom(s => s.TotalActiveBids()))
            .ForMember(m => m.ItemsAwaitingConfirmation,
                       o => o.MapFrom(s => s.Items.Count(i => i.IsAwaitingReceptionConfirmation().Equals(true))))
            .ForMember(m => m.AcquiredItems, o => o.MapFrom(s => s.AquiredItems().Count))
            .ForMember(m => m.WinningBids, o => o.ResolveUsing<WinningBidsResolver>())
            .ForMember(m => m.Items, o => o.ResolveUsing<BiddingItemResolver>());

        Mapper.CreateMap<User, UserDetailedStatus>()
            .ForMember(m => m.NumberOfRatings, o => o.MapFrom(s => s.OwnRatings.Count()))
            .ForMember(m => m.NewMessages, o => o.MapFrom(s => s.TotalUnreadMessages()))
            .ForMember(m => m.OngoingListings, o => o.MapFrom(s => s.Items.Where(i => i.IsPublished()).Count()))
            .ForMember(m => m.Rating, o => o.MapFrom(s => s.RatingAverage))
            .ForMember(m=>m.BiddingAndItems, o => o.MapFrom(s=> s))
            .ForMember(m => m.TotalCredits, o => o.MapFrom(s => s.TotalCredits()));

        Mapper.CreateMap<User, UserInfoSummaryViewModel>()
            .ForMember(m => m.DetailedStatus, o => o.MapFrom(s => s));

public class BiddingItemResolver : ValueResolver<User, List<ItemForUserBids>>
{
    protected override List<ItemForUserBids> ResolveCore(User source)
    {
        var items = new List<ItemForUserBids>();
        foreach (var bid in source.Bids)
        {
            var item = bid.Item;
            var c = new ItemForUserBids
                        {
                            BidValue = bid.Amount,
                            Description = item.Description,
                            Id = item.Id,
                            ItemThumb = item.MainImageLink(),
                            Status = source.ItemBiddingStatus(item.Id),
                            TimeLeft = TimeUtility.TimeLeft(item.EndDate),
                            Title = item.Title
                        };
            items.Add(c);
        }
        return items;
    }
}

public class WinningBidsResolver : ValueResolver<User, int>
{
    protected override int ResolveCore(User source)
    {
        return source.Bids.Where(c => c.Item.CurrentHighestBidderId().Equals(source.Id)).Count();
    }
}

问题是我没有得到任何异常来提示我出了什么问题......它只是卡住了！我怀疑我的映射正在进入某种无限循环之类的东西，但我不确定到底发生了什么……有什么办法可以调试这个问题吗？

任何帮助将不胜感激......

Answer 1

如果没有关于您收到的异常的更多信息，我只能猜测可能出了什么问题：我猜这是因为您在 MapFrom 中的未初始化集合上使用了 Linq。尝试改用ValueResolver。