最近在處理報表時發現一個問題,就是子報表的設定,在主報表中可以加入子報表,如果只有根據MSDN官方的範例去撰寫,會發現其實在運行的時候會發生錯誤,錯誤訊息[An error occurred during local report processing. Value cannot be null. Parameter name: value ],經過了同事的協助後,終於解決了這個問題,原來魔鬼真的藏在細節中。
通常我們會在主報表中拉入子報表控制項,然後設定參數
然後接下來的這一步是主要的關鍵,在報表資料的參數中,按右鍵選加入參數,然後在 (1) 參數名稱中,填入主報表傳遞的變數,接著在 (2) 勾選允許Null 值。
再過來就可以依照MSDN的範例程式去呼叫子報表囉…
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Microsoft.Reporting.WebForms;
public partial class _Default : System.Web.UI.Page
{
private DataTable orderDetailsData = null;
private DataTable LoadOrdersData()
{
// Load data from XML file
DataSet dataSet = new DataSet();
dataSet.ReadXml(@"c:\My Reports\OrderData.xml");
return dataSet.Tables[0];
}
private DataTable LoadOrderDetailsData()
{
// Load data from XML file
DataSet dataSet = new DataSet();
dataSet.ReadXml(@"c:\My Reports\OrderDetailData.xml");
return dataSet.Tables[0];
}
void DemoSubreportProcessingEventHandler(object sender, SubreportProcessingEventArgs e)
{
if (orderDetailsData == null)
orderDetailsData = LoadOrderDetailsData();
e.DataSources.Add(new ReportDataSource("DataSet1_OrderDetails", orderDetailsData));
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// Set RDL file
ReportViewer1.LocalReport.ReportPath =
@"c:\My Reports\Orders.rdlc";
// Supply a DataTable corresponding to each report dataset
ReportViewer1.LocalReport.DataSources.Add(
new ReportDataSource("DataSet1_Orders",
LoadOrdersData()));
}
// Add a handler for SubreportProcessing
ReportViewer1.LocalReport.SubreportProcessing += new
SubreportProcessingEventHandler(DemoSubreportProcessingEventHandler);
}
}
以上範例為MSDN所提供。感謝同事Robin與Kyle的鼎力相助。
參考資料:
1.MSDN:http://msdn.microsoft.com/zh-tw/library/microsoft.reporting.webforms.localreport.subreportprocessing(v=vs.80).aspx
2.http://stackoverflow.com/questions/4018533/passing-parameters-to-sub-reports-in-rdlc-under-vs-2010
3.LocalReport - 使用子報表:http://kylesheng.blogspot.tw/2013/06/localreport.html
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