错误：“以下方法或属性之间的调用不明确”？

Question

当我跑我的项目，会显示以下错误信息：

The call is ambiguous between the following methods or properties: 'Microsoft.Reporting.WinForms.ReportDataSource.ReportDataSource(string, System.Collections.IEnumerable)' and 'Microsoft.Reporting.WinForms.ReportDataSource.ReportDataSource(string, System.Data.DataTable).

为什么？

firstReportDBDataContext dc = new firstReportDBDataContext(); 
    private void Form1_Load(object sender, EventArgs e) 
    { 
     dsFirstReport.dtLoaiHangDataTable dt = new dsFirstReport.dtLoaiHangDataTable(); 
     var query = from a in dc.tblLoaiHangHoas 
        select a; 
     foreach (tblLoaiHangHoa a in query) 
     { 
      dt.Rows.Add(a.MaLoai, a.TenLoai); 
     } 
     this.reportViewer1.LocalReport.DataSources.Add(new ReportDataSource("dsFirstReport_DataSet1",dt)); 
     this.reportViewer1.RefreshReport(); 

    } 

Answer 1

从错误信息，很明显，类型dsFirstReport.dtLoaiHangDataTable继承DataTable类型和实现IEnumerable。

您可以通过将参数转换为其中一个来解决编译器的歧义。例如：

reportViewer1.LocalReport.DataSources.Add(
    new ReportDataSource("dsFirstReport_DataSet1", (IEnumerable)dt));