AutoMapper.dll中出现类型“AutoMapper.AutoMapperMappingException”的异常，但未在用户代码中处理 [英] An exception of type 'AutoMapper.AutoMapperMappingException' occurred in AutoMapper.dll but was not handled in user code
问题描述
不知怎的，我的代码不再工作了（以前使用完全相同的代码）。这是问题：
代码
我正在尝试映射一些使用此代码的ViewModels对象：
配置：
.CreateMap< BookcaseItem，FoundBookcaseItemViewModel>（）
.ForMember（x => x.Title，opt => opt.MapFrom（src => src.Book.Title））
.ForMember x => x.Authors，opt => opt.MapFrom（src => src.Book.Authors.Select（x => x.Name）.Aggregate（（i，j）=> i + ，+ j）））
.ForMember（x => x.Identifiers，opt => opt.MapFrom（src =>（！string.IsNullOrEmpty（src.Book.Isbn10）？（ISBN10 ：+ src.Book.Isbn10 +\r\\\
）：string.Empty）+
（！string.IsNullOrEmpty（src.Book.Isbn13）？（ISBN13：+ src.Book .Isbn13）：string.Empty）））
.ForMember（x => x.Pages，opt => opt.MapFrom（src => src.Book.Pages））
.ForMember （x => x.ImageUri，opt => opt.MapFro m（src => src.Book.ThumbnailUriSmall））;
用法：
public ActionResult Index（）
{
string facebookId = _accountService.GetLoggedInUserFacebookId（）;
IEnumerable< BookcaseItem> items = _bookcaseItemService.GetBookcaseItemsForUser（facebookId）;
IEnumerable< FoundBookcaseItemViewModel> viewModels = items.Select（Mapper.Map< BookcaseItem，FoundBookcaseItemViewModel>）;
返回PartialView（viewModels）;
}
错误
这会导致以下错误：
AutoMapper中出现了类型AutoMapper.AutoMapperMappingException的异常。 dll但未在用户代码中处理
调试数据
首先，我通过调用以确保没有配置错误：
Mapper.AssertConfigurationIsValid（）;
我已经在我的代码中设置了断点，并尝试调试，但是我不能感觉。 'items'集合中填有数据（由Entity Framework生成的代理类），但'viewModels'集合中填满了奇怪的数据。它有一个消息，说：
映射类型：
BookcaseItem_B9B52593B2659AC05C47AB2A6E0F7AEA9989CC34D3527DF5B6AA988ED57166FB
- > String System.Data .Entity.DynamicProxies.BookcaseItem_B9B52593B2659AC05C47AB2A6E0F7AEA9989CC34D3527DF5B6AA988ED57166FB
- > System.String
目标路径：FoundBookcaseItemViewModel.Authors
源值：
System.Data.Entity.DynamicProxies.BookcaseItem_B9B52593B2659AC05C47AB2A6E0F7AEA9989CC34D3527DF5B6AA988ED57166FB
然后有一个stacktrace属性说： / p>
在System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext（）
在System.Linq.SystemCore_EnumerableDebugView`1.get_Items（）
哦，最后还有一个名为context的属性，其中包含以下数据：
任何人都可以解释这里发生了什么，为什么我的代码不工作不再？我最近对我的解决方案做了一些修改，但是我已经把它们放回Git了，所以不应该对代码有任何影响。
我的设置
- Visual Studio 12 RC
- ASP.NET MVC 4
- .NET Framework 4.0（我有4.5但是引起了太多错误，所以我用Git回滚到4.0版）
- 实体框架5.0 RC
- AutoMapper 2.1.267
实体和ViewModel / p>
我不知道是否相关，但这里是映射的源类：
public class BookcaseItem：Entity
{
public Guid Id {get;组; }
public bool IsRenting {get;组; }
public bool IsSwapping {get;组; }
public bool IsSelling {get;组; }
public decimal RentingPrice {get;组; }
public decimal SellingPrice {get;组; }
public string Currency {get;组; }
public bool IsAvailable {get;组; }
public virtual Guid BookId {get;组; }
public virtual Guid UserId {get;组; }
public virtual Book Book {get;组; }
public virtual User User {get;组; }
public BookcaseItem（）
{
IsAvailable = true;
Currency =USD;
}
}
这是映射的目标类： / p>
public class FoundBookcaseItemViewModel
{
public Guid Id {get;组; }
public bool IsRenting {get;组; }
public bool IsSwapping {get;组; }
public bool IsSelling {get;组; }
public decimal RentingPrice {get;组; }
public decimal SellingPrice {get;组; }
public string标题{get;组; }
public string Authors {get;组; }
public string标识符{get;组; }
public int Pages {get;组; }
public string ImageUri {get;组; }
}
映射Authors属性的问题。如果Authors序列为空或为空，则此聚合调用将抛出异常。
.ForMember（x => x.Authors ，
opt => opt.MapFrom（src => src.Book.Authors.Select（x => x.Name）.Aggregate（（i，j）=> i +，+ j）））
Somehow my code doesn't work any more (it did work before with the exact same code). This is the problem:
The code
I'm trying to map some objects to ViewModels with this code:
Configuration:
Mapper.CreateMap<BookcaseItem, FoundBookcaseItemViewModel>()
.ForMember(x => x.Title, opt => opt.MapFrom(src => src.Book.Title))
.ForMember(x => x.Authors, opt => opt.MapFrom(src => src.Book.Authors.Select(x => x.Name).Aggregate((i, j) => i + ", " + j)))
.ForMember(x => x.Identifiers, opt => opt.MapFrom(src => (!string.IsNullOrEmpty(src.Book.Isbn10) ? ("ISBN10: " + src.Book.Isbn10 + "\r\n") : string.Empty) +
(!string.IsNullOrEmpty(src.Book.Isbn13) ? ("ISBN13: " + src.Book.Isbn13) : string.Empty)))
.ForMember(x => x.Pages, opt => opt.MapFrom(src => src.Book.Pages))
.ForMember(x => x.ImageUri, opt => opt.MapFrom(src => src.Book.ThumbnailUriSmall));
The usage:
public ActionResult Index()
{
string facebookId = _accountService.GetLoggedInUserFacebookId();
IEnumerable<BookcaseItem> items = _bookcaseItemService.GetBookcaseItemsForUser(facebookId);
IEnumerable<FoundBookcaseItemViewModel> viewModels = items.Select(Mapper.Map<BookcaseItem, FoundBookcaseItemViewModel>);
return PartialView(viewModels);
}
The error
This results in the following error:
An exception of type 'AutoMapper.AutoMapperMappingException' occurred in AutoMapper.dll but was not handled in user code
The debug data
First of all I ensure that there are no configuration errors by calling:
Mapper.AssertConfigurationIsValid();
I've set breakpoints all over my code and try to debug it, but I can't make sense of it. The 'items' collection is filled with data (proxy classes generated by Entity Framework), but the the 'viewModels' collection is filled with strange data. It has a 'message' that says this:
Mapping types: BookcaseItem_B9B52593B2659AC05C47AB2A6E0F7AEA9989CC34D3527DF5B6AA988ED57166FB -> String System.Data.Entity.DynamicProxies.BookcaseItem_B9B52593B2659AC05C47AB2A6E0F7AEA9989CC34D3527DF5B6AA988ED57166FB -> System.String
Destination path: FoundBookcaseItemViewModel.Authors
Source value: System.Data.Entity.DynamicProxies.BookcaseItem_B9B52593B2659AC05C47AB2A6E0F7AEA9989CC34D3527DF5B6AA988ED57166FB
And then there's a stacktrace property that says:
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.SystemCore_EnumerableDebugView`1.get_Items()
Oh and finally there's another property called 'context' with the following data:
Can anyone explain what's going on here and why my code isn't working any longer? I did a couple of changes to my solution recently, but I've rolled them back by Git, so they shouldn't have any effect on the code.
My setup
- Visual Studio 12 RC
- ASP.NET MVC 4
- .NET Framework 4.0 (I had 4.5 but that caused too many errors, so I rolled back with Git to version 4.0)
- Entity Framework 5.0 RC
- AutoMapper 2.1.267
The entity and ViewModel
I don't know if it's relevant, but here is the source class for the mapping:
public class BookcaseItem : Entity
{
public Guid Id { get; set; }
public bool IsRenting { get; set; }
public bool IsSwapping { get; set; }
public bool IsSelling { get; set; }
public decimal RentingPrice { get; set; }
public decimal SellingPrice { get; set; }
public string Currency { get; set; }
public bool IsAvailable { get; set; }
public virtual Guid BookId { get; set; }
public virtual Guid UserId { get; set; }
public virtual Book Book { get; set; }
public virtual User User { get; set; }
public BookcaseItem()
{
IsAvailable = true;
Currency = "USD";
}
}
And this is the destination class for the mapping:
public class FoundBookcaseItemViewModel
{
public Guid Id { get; set; }
public bool IsRenting { get; set; }
public bool IsSwapping { get; set; }
public bool IsSelling { get; set; }
public decimal RentingPrice { get; set; }
public decimal SellingPrice { get; set; }
public string Title { get; set; }
public string Authors { get; set; }
public string Identifiers { get; set; }
public int Pages { get; set; }
public string ImageUri { get; set; }
}
It seems like there is a problem with mapping Authors property. This Aggregate call will throw an exception if the Authors sequence is null or empty.
.ForMember(x => x.Authors,
opt => opt.MapFrom(src => src.Book.Authors.Select(x => x.Name).Aggregate((i, j) => i + ", " + j)))
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