1

我已经在网上看到了一些关于此的页面，但不幸的是示例代码是 C# 中的。我无法理解其中的大部分内容（和/或通过代码翻译器运行它），但我仍然需要帮助使其在 VB 中工作。

我的自定义功能是：

Public Shared Function GetFriendlyTitle(Title As String) As String
    Dim ConvertedTitle As String = ""
    Try
        Dim oRE As Regex = New Regex("[^a-zA-Z0-9\s]")
        ConvertedTitle = Trim(oRE.Replace(Title, "")).Replace(" ", "_")
    Catch ex As Exception
        LogError(ex)
    End Try
    Return ConvertedTitle
End Function

这是我调用返回产品的函数：

Public Shared Function GetProductByTypeAndTitle(URLFriendlyTitle As String, ProductType As ProductType)
    Try
        'don't know why, but the server threw errors if I went c.Type=Type
        Dim pt As Integer = CInt([Enum].Parse(GetType(ProductType), [Enum].GetName(GetType(ProductType), ProductType)))

        Dim context As LionsSharePressEntities = New LionsSharePressModel.LionsSharePressEntities
        return From p In context.Products Where GetFriendlyTitle(p.Title) = URLFriendlyTitle AndAlso p.Type = pt
    Catch ex As Exception
        LogError(ex)
        Return nothing
    End Try
End Function

它编译得很好，但是当我运行它时挂起。正是这条返回线做到了。

4

2 回答 2

0

尝试添加Select语句：

return From p In context.Products 
           Where GetFriendlyTitle(p.Title) = URLFriendlyTitle 
           AndAlso p.Type = pt 
           Select p
于 2013-04-23T13:57:32.640 回答
0

这个问题有点老了，似乎已经解决了。但我仍然发布此消息，希望它可能会帮助某人解决对我有用的替代解决方案。

另请注意，我无法在我的 LINQ 查询“共享”中调用我的函数，这使我的情况略有不同。我认为更有理由发布替代答案。

Public Function GetFriendlyTitle(Title As String) As String
    Dim ConvertedTitle As String = ""
    Try
        Dim oRE As Regex = New Regex("[^a-zA-Z0-9\s]")
        ConvertedTitle = Trim(oRE.Replace(Title, "")).Replace(" ", "_")
    Catch ex As Exception
        LogError(ex)
    End Try
    Return ConvertedTitle
End Function

当我遇到从 LINQ 查询中调用非共享用户定义函数的问题时，这就是我使用 OPs 代码片段作为示例解决它的方法。

Public Shared Function GetProductByTypeAndTitle(URLFriendlyTitle As String, _
                                                ProductType As ProductType)
    Try
        'don't know why, but the server threw errors if I went c.Type=Type
        Dim pt As Integer = _
                CInt([Enum].Parse(GetType(ProductType), _ 
                     [Enum].GetName(GetType(ProductType), ProductType)))
        Dim context As New LionsSharePressModel.LionsSharePressEntities

        '// Here is the lambda that will call your GetFriendlyTitle function
        Dim callUserFunc As Func(Of String, String) = _
                Function(title As String)
                    Return GetFriendlyTitle(title)
                End Function

        '// Now call Invoke on the lambda and pass in the needed param(s) from within your LINQ query
        return From p In context.Products _
               Where callUserFunc.Invoke(p.Title) = URLFriendlyTitle AndAlso p.Type = pt

        '//return From p In context.Products Where GetFriendlyTitle(p.Title) = URLFriendlyTitle AndAlso p.Type = pt

    Catch ex As Exception

        LogError(ex)
        Return nothing

    End Try
End Function
于 2015-07-17T21:55:28.550 回答