EF6 Automapper Inheritance/Abstract Class 错误
EF6 Automapper Inheritance/Abstract Class Errors
我正在构建一个 .NET Web API 使用 Entity Framework 6 和 AutoMapper 将实体映射到 DTO。当我尝试引入具有抽象基础 class 的 TPH（每个层次结构 table）时，我得到了一个非常长且非常无用（至少对我而言）的错误。错误如下，我不确定实际错误是什么。我试过用谷歌搜索它的各个部分都无济于事。
这是我的映射：
Mapper.CreateMap<ParentClass, ParentClassDTO>()
.Include<ClassA, ClassADTO>()
.Include<ClassB, ClassBDTO>();
Mapper.CreateMap<ClassA, ClassADTO>();
Mapper.CreateMap<ClassB, ClassBDTO>();
如果我从 ParentClass 中删除 abstract，错误就会消失，但 AutoMapper 不会使用子 DTO classes，它只使用 ParentClassDTO。如果我一起删除所有映射并仅通过 API return 实体，则没有错误，一切都按预期工作。
我什至不知道从哪里开始出现下面的错误，如何开始调试它（web API 运行 在调试模式下仍然只是将此错误输出到屏幕），或者什么对错误负责。我已经尽可能地简化了我的代码并尝试了其他各种方法，但似乎无法解决这个问题。
此特定映射是另一个 DTO class 中的一个集合，我正在将其创建到 return 来自 Web API 的 IQueryable<AnotherClassDTO>:
return db.AnotherClass.Project().To<AnotherClassDTO>();
AnotherClassDTO（包含抽象集合的单独 class）设置如下：
public class AnotherClassDTO
{
public IEnumerable<ParentClassDTO> Elements;
}
错误信息：
> {"message":"An error has occurred.","exceptionMessage":"The
> 'ObjectContent`1' type failed to serialize the response body for
> content type 'text/html;
> charset=utf-8'.","exceptionType":"System.InvalidOperationException","stackTrace":null,"innerException":{"message":"An
> error has occurred.","exceptionMessage":"Exception has been thrown by
> the target of an
> invocation.","exceptionType":"System.Reflection.TargetInvocationException","stackTrace":"
> at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
> arguments, Signature sig, Boolean constructor)\r\n at
> System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj,
> Object[] parameters, Object[] arguments)\r\n at
> System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags
> invokeAttr, Binder binder, Object[] parameters, CultureInfo
> culture)\r\n at System.Reflection.MethodBase.Invoke(Object obj,
> Object[] parameters)\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap(Translator
> translator, Type elementType, ColumnMap columnMap, MetadataWorkspace
> workspace, SpanIndex spanIndex, MergeOption mergeOption, Boolean
> streaming, Boolean valueLayer)\r\n at
> System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlanFactory.Prepare(ObjectContext
> context, DbQueryCommandTree tree, Type elementType, MergeOption
> mergeOption, Boolean streaming, Span span, IEnumerable`1
> compiledQueryParameters, AliasGenerator aliasGenerator)\r\n at
> System.Data.Entity.Core.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable`1
> forMergeOption)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.b__6()\r\n
> at
> System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1
> func, IDbExecutionStrategy executionStrategy, Boolean
> startLocalTransaction, Boolean releaseConnectionOnSuccess)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.b__5()\r\n
> at
> System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1
> operation)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1
> forMergeOption)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1..GetEnumerator>b__0()\r\n
> at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()\r\n at
> Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter
> writer, IEnumerable values, JsonArrayContract contract, JsonProperty
> member, JsonContainerContract collectionContract, JsonProperty
> containerProperty)\r\n at
> Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter
> writer, Object value, JsonContract valueContract, JsonProperty member,
> JsonContainerContract containerContract, JsonProperty
> containerProperty)\r\n at
> Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter
> jsonWriter, Object value, Type objectType)\r\n at
> Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter
> jsonWriter, Object value, Type objectType)\r\n at
> Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object
> value)\r\n at
> System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type
> type, Object value, Stream writeStream, Encoding
> effectiveEncoding)\r\n at
> System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type
> type, Object value, Stream writeStream, Encoding
> effectiveEncoding)\r\n at
> System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type
> type, Object value, Stream writeStream, HttpContent content)\r\n at
> System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync(Type
> type, Object value, Stream writeStream, HttpContent content,
> TransportContext transportContext, CancellationToken
> cancellationToken)\r\n--- End of stack trace from previous location
> where exception was thrown ---\r\n at
> System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
> task)\r\n at
> System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)\r\n at
> System.Runtime.CompilerServices.TaskAwaiter.GetResult()\r\n at
> System.Web.Http.WebHost.HttpControllerHandler.d__1b.MoveNext()","innerException":{"message":"An
> error has occurred.","exceptionMessage":"Exception has been thrown by
> the target of an
> invocation.","exceptionType":"System.Reflection.TargetInvocationException","stackTrace":"
> at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
> arguments, Signature sig, Boolean constructor)\r\n at
> System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags
> invokeAttr, Binder binder, Object[] parameters, CultureInfo
> culture)\r\n at System.RuntimeType.CreateInstanceImpl(BindingFlags
> bindingAttr, Binder binder, Object[] args, CultureInfo culture,
> Object[] activationAttributes, StackCrawlMark& stackMark)\r\n at
> System.Activator.CreateInstance(Type type, BindingFlags bindingAttr,
> Binder binder, Object[] args, CultureInfo culture, Object[]
> activationAttributes)\r\n at System.Activator.CreateInstance(Type
> type, Object[] args)\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorScratchpad.Compile()\r\n
> at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorScratchpad.Compile()\r\n
> at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorScratchpad.Compile()\r\n
> at
> System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap[T](ColumnMap
> columnMap, MetadataWorkspace workspace, SpanIndex spanIndex,
> MergeOption mergeOption, Boolean streaming, Boolean
> valueLayer)","innerException":{"message":"An error has
> occurred.","exceptionMessage":"Instances of abstract classes cannot be
> created.","exceptionType":"System.InvalidOperationException","stackTrace":"
> at
> System.Runtime.CompilerServices.RuntimeHelpers._CompileMethod(IRuntimeMethodInfo
> method)\r\n at
> System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType,
> Object target)\r\n at
> System.Linq.Expressions.Compiler.LambdaCompiler.CreateDelegate()\r\n
> at
> System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression
> lambda, DebugInfoGenerator debugInfoGenerator)\r\n at
> System.Linq.Expressions.Expression`1.Compile()\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorFactory`1..ctor(Int32
> depth, Int32 stateSlot, Expression`1 hasData, Expression`1 setKeys,
> Expression`1 checkKeys, CoordinatorFactory[] nestedCoordinators,
> Expression`1 element, Expression`1 wrappedElement, Expression`1
> elementWithErrorHandling, Expression`1 initializeCollection,
> RecordStateFactory[] recordStateFactories)\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorFactory`1..ctor(Int32
> depth, Int32 stateSlot, Expression hasData, Expression setKeys,
> Expression checkKeys, CoordinatorFactory[] nestedCoordinators,
> Expression element, Expression elementWithErrorHandling, Expression
> initializeCollection, RecordStateFactory[] recordStateFactories)"}}}}
2 个问题
- 错误消息明确指出您无法映射摘要class
- 您正在使用可查询扩展
Project().To<T>()，在这种情况下，它似乎受到 linq 提供程序限制的影响，如前所述
=> 使你的基础 class 具体
=> 从 IEnumerable<T> 而不是 IQueryable<T> 映射，不使用可查询扩展。
我正在构建一个 .NET Web API 使用 Entity Framework 6 和 AutoMapper 将实体映射到 DTO。当我尝试引入具有抽象基础 class 的 TPH（每个层次结构 table）时，我得到了一个非常长且非常无用（至少对我而言）的错误。错误如下，我不确定实际错误是什么。我试过用谷歌搜索它的各个部分都无济于事。
这是我的映射：
Mapper.CreateMap<ParentClass, ParentClassDTO>()
.Include<ClassA, ClassADTO>()
.Include<ClassB, ClassBDTO>();
Mapper.CreateMap<ClassA, ClassADTO>();
Mapper.CreateMap<ClassB, ClassBDTO>();
如果我从 ParentClass 中删除 abstract，错误就会消失，但 AutoMapper 不会使用子 DTO classes，它只使用 ParentClassDTO。如果我一起删除所有映射并仅通过 API return 实体，则没有错误，一切都按预期工作。
我什至不知道从哪里开始出现下面的错误，如何开始调试它（web API 运行 在调试模式下仍然只是将此错误输出到屏幕），或者什么对错误负责。我已经尽可能地简化了我的代码并尝试了其他各种方法，但似乎无法解决这个问题。
此特定映射是另一个 DTO class 中的一个集合，我正在将其创建到 return 来自 Web API 的 IQueryable<AnotherClassDTO>:
return db.AnotherClass.Project().To<AnotherClassDTO>();
AnotherClassDTO（包含抽象集合的单独 class）设置如下：
public class AnotherClassDTO
{
public IEnumerable<ParentClassDTO> Elements;
}
错误信息：
> {"message":"An error has occurred.","exceptionMessage":"The
> 'ObjectContent`1' type failed to serialize the response body for
> content type 'text/html;
> charset=utf-8'.","exceptionType":"System.InvalidOperationException","stackTrace":null,"innerException":{"message":"An
> error has occurred.","exceptionMessage":"Exception has been thrown by
> the target of an
> invocation.","exceptionType":"System.Reflection.TargetInvocationException","stackTrace":"
> at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
> arguments, Signature sig, Boolean constructor)\r\n at
> System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj,
> Object[] parameters, Object[] arguments)\r\n at
> System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags
> invokeAttr, Binder binder, Object[] parameters, CultureInfo
> culture)\r\n at System.Reflection.MethodBase.Invoke(Object obj,
> Object[] parameters)\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap(Translator
> translator, Type elementType, ColumnMap columnMap, MetadataWorkspace
> workspace, SpanIndex spanIndex, MergeOption mergeOption, Boolean
> streaming, Boolean valueLayer)\r\n at
> System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlanFactory.Prepare(ObjectContext
> context, DbQueryCommandTree tree, Type elementType, MergeOption
> mergeOption, Boolean streaming, Span span, IEnumerable`1
> compiledQueryParameters, AliasGenerator aliasGenerator)\r\n at
> System.Data.Entity.Core.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable`1
> forMergeOption)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.b__6()\r\n
> at
> System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1
> func, IDbExecutionStrategy executionStrategy, Boolean
> startLocalTransaction, Boolean releaseConnectionOnSuccess)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.b__5()\r\n
> at
> System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1
> operation)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1
> forMergeOption)\r\n at
> System.Data.Entity.Core.Objects.ObjectQuery`1..GetEnumerator>b__0()\r\n
> at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()\r\n at
> Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter
> writer, IEnumerable values, JsonArrayContract contract, JsonProperty
> member, JsonContainerContract collectionContract, JsonProperty
> containerProperty)\r\n at
> Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter
> writer, Object value, JsonContract valueContract, JsonProperty member,
> JsonContainerContract containerContract, JsonProperty
> containerProperty)\r\n at
> Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter
> jsonWriter, Object value, Type objectType)\r\n at
> Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter
> jsonWriter, Object value, Type objectType)\r\n at
> Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object
> value)\r\n at
> System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type
> type, Object value, Stream writeStream, Encoding
> effectiveEncoding)\r\n at
> System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type
> type, Object value, Stream writeStream, Encoding
> effectiveEncoding)\r\n at
> System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type
> type, Object value, Stream writeStream, HttpContent content)\r\n at
> System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync(Type
> type, Object value, Stream writeStream, HttpContent content,
> TransportContext transportContext, CancellationToken
> cancellationToken)\r\n--- End of stack trace from previous location
> where exception was thrown ---\r\n at
> System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
> task)\r\n at
> System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
> task)\r\n at
> System.Runtime.CompilerServices.TaskAwaiter.GetResult()\r\n at
> System.Web.Http.WebHost.HttpControllerHandler.d__1b.MoveNext()","innerException":{"message":"An
> error has occurred.","exceptionMessage":"Exception has been thrown by
> the target of an
> invocation.","exceptionType":"System.Reflection.TargetInvocationException","stackTrace":"
> at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
> arguments, Signature sig, Boolean constructor)\r\n at
> System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags
> invokeAttr, Binder binder, Object[] parameters, CultureInfo
> culture)\r\n at System.RuntimeType.CreateInstanceImpl(BindingFlags
> bindingAttr, Binder binder, Object[] args, CultureInfo culture,
> Object[] activationAttributes, StackCrawlMark& stackMark)\r\n at
> System.Activator.CreateInstance(Type type, BindingFlags bindingAttr,
> Binder binder, Object[] args, CultureInfo culture, Object[]
> activationAttributes)\r\n at System.Activator.CreateInstance(Type
> type, Object[] args)\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorScratchpad.Compile()\r\n
> at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorScratchpad.Compile()\r\n
> at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorScratchpad.Compile()\r\n
> at
> System.Data.Entity.Core.Common.Internal.Materialization.Translator.TranslateColumnMap[T](ColumnMap
> columnMap, MetadataWorkspace workspace, SpanIndex spanIndex,
> MergeOption mergeOption, Boolean streaming, Boolean
> valueLayer)","innerException":{"message":"An error has
> occurred.","exceptionMessage":"Instances of abstract classes cannot be
> created.","exceptionType":"System.InvalidOperationException","stackTrace":"
> at
> System.Runtime.CompilerServices.RuntimeHelpers._CompileMethod(IRuntimeMethodInfo
> method)\r\n at
> System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType,
> Object target)\r\n at
> System.Linq.Expressions.Compiler.LambdaCompiler.CreateDelegate()\r\n
> at
> System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression
> lambda, DebugInfoGenerator debugInfoGenerator)\r\n at
> System.Linq.Expressions.Expression`1.Compile()\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorFactory`1..ctor(Int32
> depth, Int32 stateSlot, Expression`1 hasData, Expression`1 setKeys,
> Expression`1 checkKeys, CoordinatorFactory[] nestedCoordinators,
> Expression`1 element, Expression`1 wrappedElement, Expression`1
> elementWithErrorHandling, Expression`1 initializeCollection,
> RecordStateFactory[] recordStateFactories)\r\n at
> System.Data.Entity.Core.Common.Internal.Materialization.CoordinatorFactory`1..ctor(Int32
> depth, Int32 stateSlot, Expression hasData, Expression setKeys,
> Expression checkKeys, CoordinatorFactory[] nestedCoordinators,
> Expression element, Expression elementWithErrorHandling, Expression
> initializeCollection, RecordStateFactory[] recordStateFactories)"}}}}
2 个问题
- 错误消息明确指出您无法映射摘要class
- 您正在使用可查询扩展
Project().To<T>()，在这种情况下，它似乎受到 linq 提供程序限制的影响，如前所述
=> 使你的基础 class 具体
=> 从 IEnumerable<T> 而不是 IQueryable<T> 映射，不使用可查询扩展。