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VB -> C#: InvalidOperationException caused by LINQ GroupBy with multiple properties

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难度
3/5
预计耗时
1-2 天
新手友好度
35/100
Issue 类型
缺陷
描述清晰度
基本清楚
活跃度
停滞
技术栈
csharp
领域
tooling

调研方向

从 issue 中的 QueryConverter 堆栈跟踪开始，使用多个 GroupBy 属性重现 VB LINQ 查询。跟踪与该失败相关的子查询和查询段转换。完成的标准是：重现案例在没有 InvalidOperationException 的情况下完成转换，并为分组查询生成有效的 C#。

由索引模型根据 Issue 内容生成。

描述

VB -> C#
VB.Net input code
Public Class ConversionTest4
    Private Class MyEntity
        Property FavoriteNumber As Integer
        Property FavoriteColor As String
        Property Name As String
    End Class
    Private Sub BugRepro()

        Dim entities As New List(Of MyEntity)

        Dim result As IEnumerable(Of String) = From e In entities
                                               Group e By e.FavoriteNumber, e.FavoriteColor Into g1 = Group
                                               Select g1.FirstOrDefault().Name

    End Sub
End Class
Erroneous output
public class ConversionTest4
    {
        private class MyEntity
        {
            public int FavoriteNumber { get; set; }
            public string FavoriteColor { get; set; }
            public string Name { get; set; }
        }
        private void BugRepro()
        {

            var entities = new List<MyEntity>();

            var result = default
#error Cannot convert QueryExpressionSyntax - see comment for details
        /* Cannot convert QueryExpressionSyntax, System.InvalidOperationException: Sequence contains more than one element
            at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
            at ICSharpCode.CodeConverter.CSharp.QueryConverter.<ConvertSubQueryAsync>d__15.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at ICSharpCode.CodeConverter.CSharp.QueryConverter.<ConvertQueryWithContinuationAsync>d__14.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at ICSharpCode.CodeConverter.CSharp.QueryConverter.<ConvertQuerySegmentsAsync>d__12.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at ICSharpCode.CodeConverter.CSharp.QueryConverter.<ConvertClausesAsync>d__7.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.<VisitQueryExpression>d__68.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at ICSharpCode.CodeConverter.CSharp.CommentConvertingVisitorWrapper.<ConvertHandledAsync>d__8`1.MoveNext()

         Input:
         From e In entities
                                                        Group e By e.FavoriteNumber, e.FavoriteColor Into g1 = Group
                                                        Select g1.FirstOrDefault().Name

          */;

        }
    }
Details
  • Product in use: VS extension
  • Version in use: 9.2.2.0
  • This is a simplified repro code
  • I believe this exception happens because the "Group e By" line contains multiple properties to group on.
主要语言
C#
星标
914
派生
242
30 天内没有已合并 PR

环境准备

从这里开始

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  3. Fork 仓库，在一个分支上完成修改。
  4. 提交 Pull Request，并在描述里引用这个 Issue 编号。

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