将LINQ查询返回给DataTable .NET 3.5？ [英] Return LINQ query to DataTable .NET 3.5?

问题描述

我想使用LINQ查询两个 DataTables （通过解析Excel文件填充），并将它们加入到匹配的字段UPC中，如下所示：

I want to query two DataTables (populated by parsing Excel files) using LINQ and join them on a matching field, "UPC", as follows:

Dim query = From c In dt.AsEnumerable() _
Join r In dtUnits.AsEnumerable() _
On c.Field(Of String)("UPC") Equals r.Field(Of String)("UPC") _
Select New With {.UPC = r.Field(Of String)("UPC")}

此外，我想将此LINQ查询结果复制到DataTable。我发现一个方法 CopyToDataTable（），但它是在.NET 4.5，我们的服务器只支持.NET 3.5。

Additionally, I want to copy this LINQ query result to a DataTable. I found a method CopyToDataTable(), but it is in .NET 4.5, and our server only supports .NET 3.5.

如何在VB .NET 3.5中模拟此功能？

What can I do to emulate this functionality in VB .NET 3.5?

谢谢！

推荐答案

CopyToDataTable 自.NET 35以来已经存在。但问题是您要创建一个 DataTable 从头开始从匿名类型。那不行。

CopyToDataTable is already there since .NET 35. But the problem is that you want to create a DataTable "from the scratch" from an anonymous type. That doesn't work.

CopyToDataTable 是 IEnumerable< DataRow> 只要。因此，您必须从加入的 DataTables 中选择一个 DataRow ：

CopyToDataTable is an extension for IEnumerable<DataRow> only. So you either have to select one DataRow from your joined DataTables:

Dim query = From c In dt.AsEnumerable() _
            Join r In dtUnits.AsEnumerable() _
            On c.Field(Of String)("UPC") Equals r.Field(Of String)("UPC") _
            Select c
Dim table = query.CopyToDataTable()

或使用这个使用反射的 ObjectShredder 不是最有效的方式（ C＃实现）。

or use this ObjectShredder which uses reflection, hence is not the most efficient way(C# implementation).

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