資料列錯誤資訊
更新： November 2007
編輯 DataTable 中的值時，若要避免必須在每次發生資料列錯誤時都回應，則可以將錯誤資訊加入至資料列中，供日後使用。針對這項用途，DataRow 物件會為每個資料列提供 RowError 屬性。將資料加入 DataRow 的 RowError 屬性中，會將 DataRow 的 HasErrors 屬性設為 true。如果 DataRow 是 DataTable 的一部分，而且 DataRow.HasErrors 為 true，則 DataTable.HasErrors 屬性亦為 true。這同樣適用於 DataTable 所隸屬的 DataSet。當您在測試錯誤時，您可以檢查 HasErrors 屬性來判斷錯誤資訊是否已加入至任何資料列。如果 HasErrors 為 true，則可以使用 DataTable 的 GetErrors 方法，只傳回和檢查發生錯誤的資料列 (如下列範例所示)。
Dim workTable As DataTable = New DataTable("Customers")
workTable.Columns.Add("CustID", Type.GetType("System.Int32"))
workTable.Columns.Add("Total", Type.GetType("System.Double"))
AddHandler workTable.RowChanged, New DataRowChangeEventHandler(AddressOf OnRowChanged)
Dim i As Int32
For i = 0 To 10
workTable.Rows.Add(New Object() {i , i *100})
Next
If workTable.HasErrors Then
Console.WriteLine("Errors in Table " & workTable.TableName)
Dim myRow As DataRow
For Each myRow In workTable.GetErrors()
Console.WriteLine("CustID = " & myRow("CustID").ToString())
Console.WriteLine(" Error = " & myRow.RowError & vbCrLf)
Next
End If
Private Shared Sub OnRowChanged( _
sender As Object, args As DataRowChangeEventArgs)
' Check for zero values.
If CDbl(args.Row("Total")) = 0 Then args.Row.RowError = _
"Total cannot be 0."
End Sub
DataTable workTable = new DataTable("Customers");
workTable.Columns.Add("CustID", typeof(Int32));
workTable.Columns.Add("Total", typeof(Double));
workTable.RowChanged += new DataRowChangeEventHandler(OnRowChanged);
for (int i = 0; i < 10; i++)
workTable.Rows.Add(new Object[] {i, i*100});
if (workTable.HasErrors)
{
Console.WriteLine("Errors in Table " + workTable.TableName);
foreach (DataRow myRow in workTable.GetErrors())
{
Console.WriteLine("CustID = " + myRow["CustID"]);
Console.WriteLine(" Error = " + myRow.RowError + "\n");
}
}
protected static void OnRowChanged(
Object sender, DataRowChangeEventArgs args)
{
// Check for zero values.
if (args.Row["Total"].Equals(0D))
args.Row.RowError = "Total cannot be 0.";
}