asp.net mvC语言 将一个(实体类)映射到多个(dto/viewModels)

Question

我试图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，我之所以在几个类之间分发信息，是因为在几个视图中都有我需要的公共信息。这就是我最终得到的：

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计算器

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类内的映射

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内部的自动映射程序

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

我想，因为我在引导程序中有所有必要的映射，所以理论上应该可以工作，显然我错了。。。我该怎么解决？

更新：

我修复了映射，并添加了几个值解析器。现在我没有得到null引用异常，但似乎有问题，因为每次我运行项目时，它都会被卡住，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，我没有得到任何例外来给我任何关于问题所在的提示。。。它只是卡住了！我怀疑我的映射正在进入某种无限循环或其他什么，但我不确定到底发生了什么。。。有什么方法可以调试这个问题吗？

任何帮助都将不胜感激。。。

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中未初始化的集合上使用了Linq。请尝试实现ValueResolver。