缺少类型映射配置或不支持的映射

Question

有人能解释这个错误的含义吗？我以前使用过automapper，但从未发生过这种错误。

错误

服务器遇到错误处理请求。异常消息是'丢失类型映射配置或不支持的映射。映射类型：Char - > QuestionDto System.Char - > CollectiveDistributedPolling.QuestionDto目标路径：QuestionDto.Question1.Question1.Question10 [0]源值：R'。

Service1.svc.cs

public Service1() { 
    Mapper.CreateMap<Question, QuestionDto>(); 
    Mapper.CreateMap<QuestionDto, Question>(); 
} 

private Question MapToQuestion(QuestionDto q) 
{ 
     return Mapper.Map<QuestionDto, Question>(q); 
} 

private QuestionDto MapToQuestionDto(Question q) <<< EXCEPTION GETS THROWN HERE 
{ 
     return Mapper.Map<Question, QuestionDto>(q); 
} 

public QuestionDto ThrowQuestion(string user) 
{ 
     return MapToQuestionDto(Database.GetInstance().ThrowQuestion(user)); 
} 

IService1.cs

[OperationContract] 
     [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.Wrapped, ResponseFormat = WebMessageFormat.Json)] 
     QuestionDto ThrowQuestion(String user); 

[DataContract] 
    public class QuestionDto 
    { 
     [DataMember] 
     public int ID { get; set; } 
     [DataMember] 
     public int next { get; set; } 
     [DataMember] 
     public String question { get; set; } 
     [DataMember] 
     public ICollection<QuestionDto> QuestionPhrase { get; set; } 
     [DataMember] 
     public QuestionDto Next{ get; set; } 
     [DataMember] 
     public ICollection<QuestionAnswerDto> QuestionAnswer { get; set; } 
     [DataMember] 
     public ICollection<UserAnswerDto> UserAnswer { get; set; } 
    } 

Question.cs

public partial class Question 
    { 
     public Question() 
     { 
      this.QuestionPhrase = new HashSet<Question>(); 
      this.QuestionAnswer = new HashSet<QuestionAnswer>(); 
      this.UserAnswer = new HashSet<UserAnswer>(); 
     } 

     public int ID { get; set; } 
     public string question { get; set; } 
     public Nullable<int> next { get; set; } 

     public virtual ICollection<Question> QuestionPhrase { get; set; } 
     public virtual Question Next { get; set; } 
     public virtual ICollection<QuestionAnswer> QuestionAnswer { get; set; } 
     public virtual ICollection<UserAnswer> UserAnswer { get; set; } 
    } 
} 

由于d anludwig我可以找出问题所在。它是与

[DataMember] 
public QuestionDto Next{ get; set; } 

但是，这似乎映射罚款我

Answer 1

这基本上意味着AutoMapper缺少有关如何映射从一个属性到另一个信息。

尽管通过查看错误无法判断，但您可以尝试以下过程来确定哪些属性缺少映射。忽略所有的目标类型属性的开始了：

Mapper.CreateMap<Question, QuestionDto>() 
    .ForMember(d => d.ID, o => o.Ignore()) 
    .ForMember(d => d.next, o => o.Ignore()) 
    .ForMember(d => d.question, o => o.Ignore()) 
    .ForMember(d => d.QuestionPhrase, o => o.Ignore()) 
    .ForMember(d => d.Next, o => o.Ignore()) 
    .ForMember(d => d.QuestionAnswer, o => o.Ignore()) 
    .ForMember(d => d.UserAnswer, o => o.Ignore()) 
    // also ignore any other properties 
; 

然后，一个接一个，取消对ForMember行，直到你的异常再次升高。 AM是无法弄清楚如何映射的属性。我怀疑是在您的收藏属性之一...

更新

我不知道是否有可能是一个递归问题怎么回事。试试这个：

.ForMember(d => d.Next, o => o.ResolveUsing(s => { 
    var tryToMap = Mapper.Map<QuestionDto>(s.Next); // exception here??? 
    return null; 
})); 

并不是说你在这里有数据问题，但是如果你这样做了，你应该预期AM会抛出。如果你的question.Next == question，我想象AM会溢出堆栈试图将一个属性映射到它的所有者一遍又一遍。