我有以下实体框架7个实体:获取表第2列的关系
public class EbookFile {
public Int32 EbookId { get; set; }
public Int32 FileId { get; set; }
public virtual Ebook Ebook { get; set; }
public virtual File File { get; set; }
}
public class File {
public Int32 Id { get; set; }
public Byte[] Content { get; set; }
public String Name { get; set; }
public virtual ICollection<EbookFile> EbooksFiles { get; set; }
}
给定一个EbookId我需要得到的ID和与之相关的所有文件的名称:
Dictionary<Int32, Dictionary<String, Int32>> files = await _context
.EbooksFiles
.Include(x => x.File)
.Where(x => result.Select(y => y.Id).Contains(x.EbookId))
.GroupBy(x => x.EbookId)
.ToDictionaryAsync(x => x.Key, x => x.ToDictionary(y => y.File.Name, y => y.File.Id));
的问题是,我也得到我不想要的内容:
SELECT [x].[EbookId], [x].[FileId], [f].[Id], [f].[Content], [f].[Name]
FROM [EbooksFiles] AS [x]
INNER JOIN [Files] AS [f] ON [x].[FileId] = [f].[Id]
我怎样才能提高我的LINQ expre ssion只将FileId和Name放入字典中?
TEST QUERY
var ids = new Int32[] { 1, 2 };
var files = _context
.EbooksFiles
.Where(x => ids.Contains(x.EbookId))
.Select(x => new { x.EbookId, x.File.Name, x.File.Id })
.GroupBy(x => x.EbookId)
.ToList();
栈跟踪
2016年4月29日十五时13分40秒[错误]已经在执行请求 System.InvalidOperationException发生未处理的异常:序列在System.Linq.Enumerable.Single [TSource](IEnumerable 1 source) at Microsoft.Data.Entity.Query.EntityQueryModelVisitor.<>c__DisplayClass79_0
1.b__0(IEnumerable 1 ps, IQuerySource qs) at Microsoft.Data.Entity.Query.EntityQueryModelVisitor.BindMemberExpressionCore[TResult](MemberExpression memberExpression, IQuerySource querySource, Func
3 memberBinder)包含多个元素在Microsoft.Data.Entity.Query.EntityQueryModelVisitor.BindMemberExpression [TResult](MemberExpression memberExpression,IQuerySource querySource,函数功能3 memberBinder) at Microsoft.Data.Entity.Query.EntityQueryModelVisitor.BindMemberExpression(MemberExpression memberExpression, Action
2 memberBinder) 在Microsoft.Data.Entity.Query.ExpressionVisitors.Internal.RequiresMaterializationExpressionVisitor.VisitMember(MemberExpression memberExpression) 在System.Linq.Expressions.MemberExpression.Accept(ExpressionVisitor访问者) 在Microsoft.Data.Entity.Query.ExpressionVisitors.ExpressionVisitorBase.Visit(表达式表达) 在System.Linq.Expressions.ExpressionVisitor.VisitAndConvert [T](ReadOnlyCollection 1 nodes, String callerName) at Remotion.Linq.Parsing.RelinqExpressionVisitor.VisitNew(NewExpression expression) at System.Linq.Expressions.NewExpression.Accept(ExpressionVisitor visitor) at Microsoft.Data.Entity.Query.ExpressionVisitors.ExpressionVisitorBase.Visit(Expression expression) at Remotion.Linq.Clauses.ResultOperators.GroupResultOperator.TransformExpressions(Func
2转换) at Remotion.Linq.QueryModel.TransformExpressions(Func 2 transformation) at Microsoft.Data.Entity.Query.ExpressionVisitors.Internal.RequiresMaterializationExpressionVisitor.FindQuerySourcesRequiringMaterialization(QueryModel queryModel) at Microsoft.Data.Entity.Query.QueryCompilationContext.FindQuerySourcesRequiringMaterialization(EntityQueryModelVisitor queryModelVisitor, QueryModel queryModel) at Microsoft.Data.Entity.Query.EntityQueryModelVisitor.CreateQueryExecutor[TResult](QueryModel queryModel) at Microsoft.Data.Entity.Storage.Database.CompileQuery[TResult](QueryModel queryModel) --- End of stack trace from previous location where exception was thrown --- at Microsoft.Data.Entity.Query.Internal.QueryCompiler.<>c__DisplayClass18_0
1.b__0() at Microsoft.Data.Entity.Query.Internal。 CompiledQueryCache.GetOrAddQuery [TResult](对象cacheKey,函数功能1 compiler) at Microsoft.Data.Entity.Query.Internal.QueryCompiler.CompileQuery[TResult](Expression query) at Microsoft.Data.Entity.Query.Internal.QueryCompiler.Execute[TResult](Expression query) at Microsoft.Data.Entity.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression) at Remotion.Linq.QueryableBase
1.GetEnumerator() 在System.Collections.Generic.List 1..ctor(IEnumerable
1集合) 在System.Linq.Enumerable.ToList [TSource](IEnumerable的1 source) at EbookGetApiModelHandler.QueryHandler.<Handle>d__4.MoveNext() in \Handlers\EbookGetApiModelHandler.cs:line 85 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MediatR.Mediator.<SendAsync>d__4
1.MoveNext() ---从先前的位置在那里引发异常--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务task) 堆栈跟踪的结尾处System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务task) 在System.Runtime.CompilerServices.TaskAwaiter 1.GetResult() at Controllers.EbookApiController.<Get>d__2.MoveNext() in \Controllers\EbookApiController.cs:line 30 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNet.Mvc.Controllers.ControllerActionExecutor.<CastToObject>d__8
1.MoveNext() ---抛出异常的上一个位置的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskA waiter.ThrowForNonSuccess(任务任务) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务任务) at Microsoft.AspNet.Mvc.Controllers.ControllerActionInvoker.d__6.MoveNext() ---从前一个位置结束堆栈跟踪其中引发异常--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务task) 在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务task) 在System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(任务任务) at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.d__53。MoveNext() ---上一个位置抛出异常的堆栈跟踪结束--- at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.d__44.MoveNext() ---上一个位置的堆栈跟踪结束位置异常被抛出--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务task) 在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务task) 在Microsoft.AspNet.Mvc.Infrastructure.MvcRouteHandler.d__6。 MoveNext() ---从之前位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务任务) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebugger通知(任务任务) at Microsoft.AspNet.Mvc.Routing.InnerAttributeRoute.d__10.MoveNext() ---从之前位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter。 ThrowForNonSuccess(任务任务) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务任务) at Microsoft.AspNet.Routing.RouteCollection.d__9.MoveNext() ---从上一个位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNet.Builder.RouterMiddleware.d__4.MoveN EXT() ---在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务task) 从先前的位置堆栈跟踪,其中引发异常--- 结束在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务任务) at Microsoft.AspNet.Authentication.AuthenticationMiddleware 1.<Invoke>d__18.MoveNext() --- End of stack trace from previous location where exception was thrown --- at Microsoft.AspNet.Authentication.AuthenticationMiddleware
1.d__18.MoveNext() ---抛出异常的上一个位置的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task ) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNet.Authentication.AuthenticationMiddleware 1.<Invoke>d__18.MoveNext() --- End of stack trace from previous location where exception was thrown --- at Microsoft.AspNet.Authentication.AuthenticationMiddleware
1.d__18.MoveNext() ---从以前位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNet.Authentication.AuthenticationMiddleware 1.<Invoke>d__18.MoveNext() --- End of stack trace from previous location where exception was thrown --- at Microsoft.AspNet.Authentication.AuthenticationMiddleware
1.d__18.MoveNext() ---从以前位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务任务) at Microsoft.AspNet.Authentication.AuthenticationMiddleware 1.<Invoke>d__18.MoveNext() --- End of stack trace from previous location where exception was thrown --- at Microsoft.AspNet.Authentication.AuthenticationMiddleware
1.d__18.MoveNext() ---堆栈跟踪结束米以前的位置在那里引发异常--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务task) 在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务task) 在Microsoft.AspNet.Localization.RequestLocalizationMiddleware。 d__4.MoveNext() ---从以前位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(任务任务) at Microsoft.AspNet.Diagnostics.Entity.MigrationsEndPointMiddleware.d__5。MoveNext() ---从之前位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task ) at Microsoft.AspNet.Diagnostics.Entity.DatabaseErrorPageMiddleware.d__6.MoveNext() ---上一个位置抛出异常的堆栈跟踪结束--- 位于Microsoft.AspNet.Diagnostics.Entity.DatabaseErrorPageMiddleware.d__6。 MoveNext() ---从之前的位置抛出异常的堆栈跟踪结束--- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(任务任务) at System.Runtime.CompilerServices.TaskAwaiter.Handl eNonSuccessAndDebuggerNotification(任务task) 在Microsoft.AspNet.Diagnostics.DeveloperExceptionPageMiddleware.d__7.MoveNext()