自动映射器显示错误“指定的演员表无效。”

Posted 2023-02-22

【中文标题】自动映射器显示错误“指定的演员表无效。”

【英文标题】：automapper showing error "Specified cast is not valid."

【发布时间】：2013-05-08 11:34:04

【问题描述】：

在将 DataTable 与模型映射时出错

这是我的代码

       if (file.ContentLength > 0)
        
            var extension = Path.GetExtension(file.FileName);
            if (extension != null && extension.ToLower() != ".xlsx")
            
                return "please upload file with extension .xlsx";
            

            Stream stream = file.InputStream;
            IExcelDataReader excelReader = ExcelReaderFactory.CreateOpenXmlReader(stream);
            excelReader.IsFirstRowAsColumnNames = true;
            DataSet result = excelReader.AsDataSet();
            if (result.Tables.Count > 0)
            
                Mapper.Reset();
                Mapper.CreateMap<IDataReader, ExcelFeedbackRecord>();

                var results = Mapper.Map<IDataReader, IList<ExcelFeedbackRecord>>(result.Tables[0].CreateDataReader());

            
            return result.Tables[0].Rows.Count.ToString();
        

错误的堆栈跟踪如下

       [InvalidCastException: Specified cast is not valid.]    DynamicCreate(IDataRecord ) +1673   

AutoMapper.Mappers.DataReaderMapper.Map(ResolutionContext 上下文， IMappingEngineRunner 映射器）+433 AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.Map(ResolutionContext 上下文）+347

[AutoMapperMappingException: 试图将 System.Data.IDataReader 映射到 System.Collections.Generic.IList1[[SkillKindle.BLL.Feedbacks.ExcelFeedbackRecord, SkillKindle.BLL, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]. Exception of type 'AutoMapper.AutoMapperMappingException' was thrown.] AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.Map(ResolutionContext context) +433 AutoMapper.MappingEngine.Map(Object source, Type sourceType, Type destinationType, Action1 选择）+353 AutoMapper.MappingEngine.Map(TSource 源) +564 AutoMapper.Mapper.Map(TSource 源) +461 SkillKindleAdmin.Controllers.FeedbackController.ExcelUpload(HttpPostedFileBase 文件）在 d:\Skill Online\trunk\SkillKindleAdmin\Controllers\FeedbackController.cs:57 lambda_method(闭包, ControllerBase, Object[]) +107 System.Web.Mvc.ActionMethodDispatcher.Execute（ControllerBase 控制器，Object[] 参数）+286 System.Web.Mvc.ReflectedActionDescriptor.Execute（ControllerContext 控制器上下文，IDictionary2 parameters) +655 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 参数）+326 System.Web.Mvc.Async.AsyncControllerActionInvoker.InvokeSynchronousActionMethod（ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters) +317 System.Web.Mvc.Async.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41() +219 System.Web.Mvc.Async.<>c__DisplayClass81.b__7(IAsyncResult ) +275 System.Web.Mvc.Async.WrappedAsyncResult1.End() +328 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +492 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +261 System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +268 System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +461 System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult) +235 System.Web.Mvc.Async.WrappedAsyncResult1.End() +328 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, 对象标签) +492 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters（IAsyncResult asyncResult) +262 System.Web.Mvc.Async.c_DisplayClass2a.b_20() +203 System.Web.Mvc.Async.c_DisplayClass25.b_22(IAsyncResult asyncResult) +392 System.Web.Mvc.Async.WrappedAsyncResult1.End() +316 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +387 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +285 System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +234 System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +275 System.Web.Mvc.Async.WrappedAsyncResult1.End() +333 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, 对象标签）+397 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, 对象标签）+266 System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +253 System.Web.Mvc.Async.c_DisplayClass4.b__3(IAsyncResult ar) +275 System.Web.Mvc.Async.WrappedAsyncResult1.End() +333 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +397 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +266 System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +254 System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +226 System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +230 System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +275 System.Web.Mvc.Async.WrappedAsyncResult1.End() +333 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, 对象标签）+397 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, 对象标签）+266 System.Web.Mvc.MvcHandler.EndProcessRequest（IAsyncResult asyncResult） +255 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult 结果）+225 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +1086 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +603

【参考方案1】：

您确定数据读取器返回的列与对象 ExcelFeedbackRecord 中的属性字段完全匹配，包括大小写？ 如果不是，则必须在创建地图时添加配置。

【讨论】：

首先感谢您的帮助，是的，列与属性字段完全匹配，但它不是字符串类型。现在它固定了

【参考方案2】：

问题是当我们用模型映射DataSet时，模型的所有属性都必须是字符串类型，然后你可以使用automapper的CustomTypeConversion方法。