DataRowView クラス

完全な機能を持つ Windows フォーム コントロールとして公開されている DataRow のカスタマイズされたビューを表します。

この型のすべてのメンバの一覧については、DataRowView メンバ を参照してください。

System.Object
   System.Data.DataRowView

Public Class DataRowView
   Implements ICustomTypeDescriptor, IEditableObject, _
   IDataErrorInfo
[C#]
public class DataRowView : ICustomTypeDescriptor, IEditableObject,
   IDataErrorInfo
[C++]
public __gc class DataRowView : public ICustomTypeDescriptor,
   IEditableObject, IDataErrorInfo
[JScript]
public class DataRowView implements ICustomTypeDescriptor,
   IEditableObject, IDataErrorInfo

スレッドセーフ

この型は、マルチスレッド読み取り操作に対して安全です。すべての書き込み操作の同期をとる必要があります。

解説

データを (DataGrid コントロールなどで) 表示する場合は、1 行につき 1 つのバージョンだけを表示できます。表示されている行は DataRowView です。

DataRowView は、Default、Original、Current、および Proposed という 4 種類のバージョン状態のいずれか 1 つをとることができます。

DataRow で BeginEdit を呼び出した後で編集した値は Proposed 値になります。 CancelEdit または EndEdit のどちらかを呼び出すまでは、行には Original バージョンと Proposed バージョンが格納されています。CancelEdit を呼び出すと、提示されたバージョンが破棄され、値が元の値に戻ります。EndEdit を呼び出すと、DataRowView には Proposed バージョンがなくなり、提示された値が現在の値になります。既定値は、既定値が定義されている列を含む行でだけ使用できます。

使用例

[Visual Basic, C#, C++] 2 つの列で DataTable を作成し、1 つの行をこのテーブルに追加する例を次に示します。行をテーブルに追加すると、行の各種のバージョンが出力されます。たとえば、 BeginEdit が呼び出され、行の値が変更され、Original、Proposed、Current の各値が出力されます。

 
Private Sub DemonstrateRowVersions()
    ' Create a DataTable.
    Dim myTable As New DataTable("myTable")
    ' Create two columns. Set DataType and DefaultValue properties.
    Dim col1 As New DataColumn("col1")
    col1.DataType = System.Type.GetType("System.String")
    col1.DefaultValue = "myDefaultValue"
    Dim col2 As New DataColumn("col2")
    col2.DataType = System.Type.GetType("System.Decimal")
    col2.DefaultValue = 0.1
    ' Add Columns to the DataTable.
    myTable.Columns.Add(col1)
    myTable.Columns.Add(col2)
    Dim newRow As DataRow
    ' Create one row and add it to the DataRow collection.
    newRow = myTable.NewRow()
    newRow(col1) = "Nitrogen"
    newRow(col2) = 33
    myTable.Rows.Add(newRow)
    ' Invoke AcceptChanges on the table.
    myTable.AcceptChanges()
    ' Print the current values:
    PrintRowVersion(myTable, DataRowVersion.Current)
       
    ' Change values in the table. 
    myTable.Rows(0).BeginEdit()
    myTable.Rows(0)("col1") = "New Component"
    myTable.Rows(0)("col2") = 100
    ' Print the proposed values.
    If myTable.Rows(0).HasVersion(DataRowVersion.Proposed) Then
        Console.WriteLine _
           (myTable.Rows(0)("col1", DataRowVersion.Proposed).ToString())
        Console.WriteLine _
           (myTable.Rows(0)("col2", DataRowVersion.Proposed).ToString())
    End If
    ' Print the original values.
    If myTable.Rows(0).HasVersion(DataRowVersion.Original) Then
        Console.WriteLine _
           (myTable.Rows(0)("col1", DataRowVersion.Original).ToString())
        Console.WriteLine _
           (myTable.Rows(0)("col2", DataRowVersion.Original).ToString())
    End If
    ' Cancel the edit.
    myTable.Rows(0).CancelEdit()
    ' Print the Current values.
    If myTable.Rows(0).HasVersion(DataRowVersion.Current) Then
        Console.WriteLine _
           (myTable.Rows(0)("col1", DataRowVersion.Current).ToString())
        Console.WriteLine _
           (myTable.Rows(0)("col2", DataRowVersion.Current).ToString())
    End If
    ' Try to print the proposed values again--gone after cancel edit.
    ' Print the proposed values.
    If myTable.Rows(0).HasVersion(DataRowVersion.Proposed) Then
        Console.WriteLine _
           (myTable.Rows(0)("col1", DataRowVersion.Proposed).ToString())
        Console.WriteLine _
           (myTable.Rows(0)("col2", DataRowVersion.Proposed).ToString())
    End If
    ' Change the values again.
    myTable.Rows(0).BeginEdit()
    myTable.Rows(0)("col1") = "New Value"
    myTable.Rows(0)("col2") = 100.1
    ' Print the proposed values.
    PrintRowVersion(myTable, DataRowVersion.Proposed)
    ' End the edit.
    myTable.Rows(0).EndEdit()
    PrintRowVersion(myTable, DataRowVersion.Current)
    PrintRowVersion(myTable, DataRowVersion.Proposed)
    ' Add a new row.
    newRow = myTable.NewRow()
    myTable.Rows.Add(newRow)
    ' Print default rows.
    PrintRowVersion(myTable, DataRowVersion.Default)
    ' Try to print original rows--there is only one row.
    PrintRowVersion(myTable, DataRowVersion.Original)
    ' Try to print proposed version--there are no rows.
    PrintRowVersion(myTable, DataRowVersion.Proposed)
    ' Print the current version--two rows.
    PrintRowVersion(myTable, DataRowVersion.Current)
    ' Invoke AcceptChanges on the new row.
    myTable.Rows(1).AcceptChanges()
    ' Print the original rows--two are now available.
    PrintRowVersion(myTable, DataRowVersion.Original)
End Sub 'DemonstrateRowVersions
   
Private Sub PrintRowVersion(dt As DataTable, ver As DataRowVersion)
    ' Print a new line and the version using the ReturnRowVersion function.
    Console.WriteLine(ControlChars.Cr + ver.ToString() + " Version:")
    ' Print the value of each column in each row.
    Try
        Dim row As DataRow
        For Each row In  dt.Rows
            ' Print the specified version of the row's value.
            Console.Write(row(0, ver).ToString() + ", ")
            Console.Write(row(1, ver).ToString() + ControlChars.Cr)
        Next row
    Catch e As Exception
    ' Process exception and return.
         Dim log As System.Diagnostics.EventLog = New System.Diagnostics.EventLog()
         log.Source = "My Application"
         log.WriteEntry(e.ToString())
         Console.WriteLine("Exception of type {0} occurred.", e.GetType().ToString())
    End Try
End Sub

[C#] 
private void DemonstrateRowVersions(){
   // Create a DataTable.
   DataTable myTable = new DataTable("myTable");
   // Create two columns. Set DataType and DefaultValue properties.
   DataColumn col1 = new DataColumn("col1");
   col1.DataType=System.Type.GetType("System.String");
   col1.DefaultValue= "myDefaultValue";
   DataColumn col2 = new DataColumn("col2");
   col2.DataType=System.Type.GetType("System.Decimal");
   col2.DefaultValue=.1;
   // Add Columns to the DataTable.
   myTable.Columns.Add (col1);
   myTable.Columns.Add(col2);
   DataRow newRow;
   // Create one row and add it to the DataRow collection.
   newRow = myTable.NewRow();
   newRow[col1]="Nitrogen";
   newRow[col2]=33;
   myTable.Rows.Add(newRow);
   // Invoke AcceptChanges on the table.
   myTable.AcceptChanges();
   // Print the current values:
   PrintRowVersion(myTable, DataRowVersion.Current);

   // Change values in the table. 
   myTable.Rows[0].BeginEdit();
   myTable.Rows[0]["col1"]= "New Component";
   myTable.Rows[0]["col2"]= 100;
   // Print the proposed values.
   if(myTable.Rows[0].HasVersion(DataRowVersion.Proposed)){
      Console.WriteLine(myTable.Rows[0]["col1", DataRowVersion.Proposed]);
      Console.WriteLine(myTable.Rows[0]["col2", DataRowVersion.Proposed]);
   }
   // Print the original values.
   if(myTable.Rows[0].HasVersion(DataRowVersion.Original)){
      Console.WriteLine(myTable.Rows[0]["col1", DataRowVersion.Original]);
      Console.WriteLine(myTable.Rows[0]["col2", DataRowVersion.Original]);
   }
   // Cancel the edit.
   myTable.Rows[0].CancelEdit();
   // Print the Current values.
   if(myTable.Rows[0].HasVersion(DataRowVersion.Current)){
      Console.WriteLine(myTable.Rows[0]["col1", DataRowVersion.Current]);
      Console.WriteLine(myTable.Rows[0]["col2", DataRowVersion.Current]);
   }
   // Try to print the proposed values again--gone after cancel edit.
   // Print the proposed values.
   if(myTable.Rows[0].HasVersion(DataRowVersion.Proposed)){
      Console.WriteLine(myTable.Rows[0]["col1", DataRowVersion.Proposed]);
      Console.WriteLine(myTable.Rows[0]["col2", DataRowVersion.Proposed]);
   }
   // Change the values again.
   myTable.Rows[0].BeginEdit();
   myTable.Rows[0]["col1"]="New Value";
   myTable.Rows[0]["col2"]=100.1;
   // Print the proposed values.
   PrintRowVersion(myTable, DataRowVersion.Proposed);
   // End the edit.
   myTable.Rows[0].EndEdit();
   PrintRowVersion(myTable, DataRowVersion.Current);
   PrintRowVersion(myTable, DataRowVersion.Proposed);
   // Add a new row.
   newRow = myTable.NewRow();
   myTable.Rows.Add(newRow);
   // Print default rows.
   PrintRowVersion(myTable, DataRowVersion.Default);
   // Try to print original rows--there is only one row.
   PrintRowVersion(myTable, DataRowVersion.Original);
   // Try to print proposed version--there are no rows.
   PrintRowVersion(myTable, DataRowVersion.Proposed);
   // Print the current version--two rows.
   PrintRowVersion(myTable, DataRowVersion.Current);
   // Invoke AcceptChanges on the new row.
   myTable.Rows[1].AcceptChanges();
   // Print the original rows--two are now available.
   PrintRowVersion(myTable, DataRowVersion.Original);
}  
 
private void PrintRowVersion(DataTable dt, DataRowVersion ver){
   // Print a new line and the version using the ReturnRowVersion function.
   Console.WriteLine("\n" + ver.ToString() + " Version:");
   // Print the value of each column in each row.
   try{
      foreach(DataRow row in dt.Rows ) {
      // Print the specified version of the row's value.
      Console.Write(row[0,ver] + ", ");
      Console.Write(row[1,ver] + "\n");
      }
   }
   catch(Exception e) {
   // Process exception and return.
       System.Diagnostics.EventLog log = new System.Diagnostics.EventLog();
       log.Source = "My Application";
       log.WriteEntry(e.ToString());
       Console.WriteLine("Exception of type {0} occurred.", e.GetType());
   }
}

[C++] 
private:
 void DemonstrateRowVersions(){
    // Create a DataTable.
    DataTable* myTable = new DataTable(S"myTable");
    // Create two columns. Set DataType and DefaultValue properties.
    DataColumn* col1 = new DataColumn(S"col1");
    col1->DataType=System::Type::GetType(S"System.String");
    col1->DefaultValue= S"myDefaultValue";
    DataColumn* col2 = new DataColumn(S"col2");
    col2->DataType=System::Type::GetType(S"System.Decimal");
    col2->DefaultValue=__box(.1);
    // Add Columns to the DataTable.
    myTable->Columns->Add (col1);
    myTable->Columns->Add(col2);
    DataRow* newRow;
    // Create one row and add it to the DataRow collection.
    newRow = myTable->NewRow();
    newRow->Item[col1]=S"Nitrogen";
    newRow->Item[col2]=__box(33);
    myTable->Rows->Add(newRow);
    // Invoke AcceptChanges on the table.
    myTable->AcceptChanges();
    // Print the current values:
    PrintRowVersion(myTable, DataRowVersion::Current);
 
    // Change values in the table. 
    myTable->Rows->Item[0]->BeginEdit();
    myTable->Rows->Item[0]->Item[S"col1"]= S"New Component";
    myTable->Rows->Item[0]->Item[S"col2"]= __box(100);
    // Print the proposed values.
    if(myTable->Rows->Item[0]->HasVersion(DataRowVersion::Proposed)){
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col1", DataRowVersion::Proposed]);
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col2", DataRowVersion::Proposed]);
    }
    // Print the original values.
    if(myTable->Rows->Item[0]->HasVersion(DataRowVersion::Original)){
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col1", DataRowVersion::Original]);
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col2", DataRowVersion::Original]);
    }
    // Cancel the edit.
    myTable->Rows->Item[0]->CancelEdit();
    // Print the Current values.
    if(myTable->Rows->Item[0]->HasVersion(DataRowVersion::Current)){
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col1", DataRowVersion::Current]);
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col2", DataRowVersion::Current]);
    }
    // Try to print the proposed values again--gone after cancel edit.
    // Print the proposed values.
    if(myTable->Rows->Item[0]->HasVersion(DataRowVersion::Proposed)){
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col1", DataRowVersion::Proposed]);
       Console::WriteLine(myTable->Rows->Item[0]->Item[S"col2", DataRowVersion::Proposed]);
    }
    // Change the values again.
    myTable->Rows->Item[0]->BeginEdit();
    myTable->Rows->Item[0]->Item[S"col1"]=S"New Value";
    myTable->Rows->Item[0]->Item[S"col2"]=__box(100.1);
    // Print the proposed values.
    PrintRowVersion(myTable, DataRowVersion::Proposed);
    // End the edit.
    myTable->Rows->Item[0]->EndEdit();
    PrintRowVersion(myTable, DataRowVersion::Current);
    PrintRowVersion(myTable, DataRowVersion::Proposed);
    // Add a new row.
    newRow = myTable->NewRow();
    myTable->Rows->Add(newRow);
    // Print default rows.
    PrintRowVersion(myTable, DataRowVersion::Default);
    // Try to print original rows--there is only one row.
    PrintRowVersion(myTable, DataRowVersion::Original);
    // Try to print proposed version--there are no rows.
    PrintRowVersion(myTable, DataRowVersion::Proposed);
    // Print the current version--two rows.
    PrintRowVersion(myTable, DataRowVersion::Current);
    // Invoke AcceptChanges on the new row.
    myTable->Rows->Item[1]->AcceptChanges();
    // Print the original rows--two are now available.
    PrintRowVersion(myTable, DataRowVersion::Original);
 }  
  
 void PrintRowVersion(DataTable* dt, DataRowVersion ver){
    // Print a new line and the version using the ReturnRowVersion function.
    Console::WriteLine(S"\n{0} Version:", __box(ver));
    // Print the value of each column in each row.
    try{
       System::Collections::IEnumerator* myEnum = dt->Rows->GetEnumerator();
       while (myEnum->MoveNext())
       {
          DataRow* row = __try_cast<DataRow*>(myEnum->Current);
       // Print the specified version of the row's value.
       Console::Write(S"{0}, ", row->Item[0,ver]);
       Console::Write(S"{0}\n", row->Item[1,ver]);
       }
    }
    catch(Exception* e) {
    // Process exception and return.
        System::Diagnostics::EventLog* log = new System::Diagnostics::EventLog();
        log->Source = S"My Application";
        log->WriteEntry(e->ToString());
        Console::WriteLine(S"Exception of type {0} occurred.", e->GetType());
    }
 }

[JScript] JScript のサンプルはありません。Visual Basic、C#、および C++ のサンプルを表示するには、このページの左上隅にある言語のフィルタ ボタン をクリックします。

必要条件

名前空間: System.Data

プラットフォーム: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 ファミリ, .NET Compact Framework - Windows CE .NET

アセンブリ: System.Data (System.Data.dll 内)

参照

DataRowView メンバ | System.Data 名前空間 | DataRow