尝试从访问中获取数据时重载解析失败

Question

我正在编写 POS 代码，但在尝试查看 access 数据库中的特定数据时遇到了问题。每次我尝试都会收到此错误：

错误 1 ​​重载解析失败，因为没有可访问的“新”最适合这些参数：

'Public Sub New(name As String, dataSourceValue As System.Collections.IEnumerable)'：不是最具体的。

'Public Sub New(name As String, dataSourceValue As System.Data.DataTable)': 不是最具体的。

C:\Users\EMIL\Documents\Visual Studio 2010\Projects\P.O.S\FrmMain.vb 402 17 AdvanceLoginForm

谁能告诉我我的代码有什么问题

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
    If ComboBox1.Text = "Total Profit for all time" Then
        Dim TA As New POSDSTableAdapters.TotalProfitForAllTimeTableAdapter
        Dim TmpDS As New POSDS
        TA.Fill(TmpDS.TotalProfitForAllTime)

        'clear previous datasource
        RV.LocalReport.DataSources.Clear()

        'create new datasource
        Dim RDS As New Microsoft.Reporting.WinForms.ReportDataSource("POSDS_TotalProfitForAllTime.rdlc", TmpDS.TotalProfitForAllTime)

        RV.LocalReport.DataSources.Add(RDS)
        RV.LocalReport.ReportEmbeddedResource = "POS.TotalProfitForAllTime.rdlc"
        RV.RefreshReport()
    ElseIf ComboBox1.Text = "Total Profit between two dates" Then
        Dim TA As New POSDSTableAdapters.TotalProfitForAllTimeTableAdapter
        Dim TmpDS As New POSDS

        TA.FillByFilteringBetweenTwoDates(TmpDS.TotalProfitForAllTime, DateTimePicker1.Value, DateTimePicker2.Value)

        'clear previous datasource
        RV.LocalReport.DataSources.Clear()

        'create new datasource 
        Dim RDS As New Microsoft.Reporting.WinForms.ReportDataSource("POSDS_TotalProfitForAllTime.rdlc", TmpDS.TotalProfitForAllTime)

        RV.LocalReport.DataSources.Add(RDS)
        RV.LocalReport.ReportEmbeddedResource = "POS.TotalProfitBetweenTwoDates.rdlc"
        RV.RefreshReport()
    End If
End sub

错误在：

Dim RDS As New Microsoft.Reporting.WinForms.ReportDataSource("POSDS_TotalProfitForAllTime.rdlc", TmpDS.TotalProfitForAllTime)

Answer 1

您可以将强类型 DataTable 转换为 DataTable 以解决此歧义问题：

Dim table As DataTable = DirectCast(TmpDS.TotalProfitForAllTime, DataTable)
Dim RDS As New Microsoft.Reporting.WinForms.ReportDataSource("POSDS_TotalProfitForAllTime.rdlc", table)

问题是在 2010 年有 two methods which are possible，一个是 DataTable，一个是 IEnumerable。强类型的DataTable 继承自TypedTableBase(Of T)，后者继承自/实现：

• DataTable,
• IEnumerable(Of T),
• IEnumerable

这就是为什么编译器不知道它应该使用哪个构造函数。他可以选择两个重载，所以你需要明确告诉编译器你想要什么。