指定した TextWriter と XmlWriteMode を使用して、 DataSet の現在のデータを書き込みます。オプションでスキーマを書き込むこともできます。スキーマを書き込むには、 XMLWriteMode パラメータの値を WriteSchema に設定します。
Overloads Public Sub WriteXml( _
ByVal writer As TextWriter, _ ByVal mode As XmlWriteMode _)
[C#]
public void WriteXml(TextWriterwriter,XmlWriteModemode);
[C++]
public: void WriteXml(TextWriter* writer,XmlWriteModemode);
[JScript]
public function WriteXml(
writer : TextWriter,mode : XmlWriteMode);
パラメータ
- writer
ドキュメントの書き込みに使用する System.IO.TextWriter オブジェクト。 - mode
XmlWriteMode 値の 1 つ。
解説
WriteXml メソッドを使用すると、 DataSet から XML ドキュメントに、データだけ、またはデータとスキーマの両方を書き込むことができます。これに対して、 WriteXmlSchema メソッドは、スキーマだけを書き込みます。データとスキーマの両方を書き込むには、 WriteXmlMode パラメータを WriteSchema に設定します。
それぞれ ReadXml メソッドと ReadXmlSchema メソッドでも同様です。XML データ、またはスキーマとデータの両方を DataSet に読み込むには、 ReadXml メソッドを使用します。スキーマだけを読み込むには、 ReadXmlSchema メソッドを使用します。
使用例
[Visual Basic, C#, C++] 初めに 1 つの DataTable 、2 列、および 10 行で単純な DataSet を作成する例を次に示します。 DataSet のスキーマとデータは、 WriteXml メソッドの呼び出しによってディスクに書き込みます。2 番目の DataSet を作成し、 ReadXml メソッドを使用して、スキーマとデータを格納します。
Private Sub DemonstrateReadWriteXMLDocumentWithStreamReader()
' Create a DataSet with one table and two columns.
Dim OriginalDataSet As New DataSet("myDataSet")
OriginalDataSet.Namespace = "NetFrameWork"
Dim myTable As New DataTable("myTable")
Dim c1 As New DataColumn("id", Type.GetType("System.Int32"))
c1.AutoIncrement = True
Dim c2 As New DataColumn("item")
myTable.Columns.Add(c1)
myTable.Columns.Add(c2)
OriginalDataSet.Tables.Add(myTable)
' Add ten rows.
Dim newRow As DataRow
Dim i As Integer
For i = 0 To 9
newRow = myTable.NewRow()
newRow("item") = "item " + i.ToString()
myTable.Rows.Add(newRow)
Next i
OriginalDataSet.AcceptChanges()
' Print out values of each table in the DataSet using the
' function defined below.
PrintValues(OriginalDataSet, "Original DataSet")
' Write the schema and data to XML file with StreamWriter.
Dim xmlFilename As String = "myXmlDocument.xml"
' Create a new StreamWriter.
Dim myStreamWriter As New System.IO.StreamWriter(xmlFilename)
' Use WriteXml to write the document.
OriginalDataSet.WriteXml(myStreamWriter)
' Close the FileStream.
myStreamWriter.Close()
' Dispose of the original DataSet.
OriginalDataSet.Dispose()
' Create a new DataSet.
Dim newDataSet As New DataSet("New DataSet")
' Create a StreamReader to read the file.
Dim myStreamReader As New System.IO.StreamReader(xmlFilename)
' Read the XML document into the DataSet.
newDataSet.ReadXml(myStreamReader)
' Close the StreamReader.
myStreamReader.Close()
' Print out values of each table in the DataSet using the
' function defined below.
PrintValues(newDataSet, "New DataSet")
End Sub
Private Sub PrintValues(ds As DataSet, label As String)
Console.WriteLine(ControlChars.Cr + label)
Dim t As DataTable
For Each t In ds.Tables
Console.WriteLine("TableName: " + t.TableName)
Dim r As DataRow
For Each r In t.Rows
Dim c As DataColumn
For Each c In t.Columns
Console.Write(ControlChars.Tab + " " + r(c).ToString())
Next c
Console.WriteLine()
Next r
Next t
End Sub
[C#]
private void DemonstrateReadWriteXMLDocumentWithStreamReader(){
// Create a DataSet with one table and two columns.
DataSet OriginalDataSet = new DataSet("myDataSet");
OriginalDataSet.Namespace= "NetFrameWork";
DataTable myTable = new DataTable("myTable");
DataColumn c1 = new DataColumn("id", Type.GetType("System.Int32"));
c1.AutoIncrement= true;
DataColumn c2 = new DataColumn("item");
myTable.Columns.Add(c1);
myTable.Columns.Add(c2);
OriginalDataSet.Tables.Add(myTable);
// Add ten rows.
DataRow newRow;
for(int i = 0; i < 10; i++){
newRow = myTable.NewRow();
newRow["item"]= "item " + i;
myTable.Rows.Add(newRow);
}
OriginalDataSet.AcceptChanges();
// Print out values of each table in the DataSet using the
// function defined below.
PrintValues(OriginalDataSet, "Original DataSet");
// Write the schema and data to XML file with StreamWriter.
string xmlFilename = "myXmlDocument.xml";
// Create a new StreamWriter.
System.IO.StreamWriter myStreamWriter =
new System.IO.StreamWriter(xmlFilename);
// Use WriteXml to write the document.
OriginalDataSet.WriteXml(myStreamWriter);
// Close the FileStream.
myStreamWriter.Close();
// Dispose of the original DataSet.
OriginalDataSet.Dispose();
// Create a new DataSet.
DataSet newDataSet = new DataSet("New DataSet");
// Create a StreamReader to read the file.
System.IO.StreamReader myStreamReader =
new System.IO.StreamReader(xmlFilename);
// Read the XML document into the DataSet.
newDataSet.ReadXml(myStreamReader);
// Close the StreamReader.
myStreamReader.Close();
// Print out values of each table in the DataSet using the
// function defined below.
PrintValues(newDataSet,"New DataSet");
}
private void PrintValues(DataSet ds, string label){
Console.WriteLine("\n" + label);
foreach(DataTable t in ds.Tables){
Console.WriteLine("TableName: " + t.TableName);
foreach(DataRow r in t.Rows){
foreach(DataColumn c in t.Columns){
Console.Write("\t " + r[c] );
}
Console.WriteLine();
}
}
}
[C++]
private:
void DemonstrateReadWriteXMLDocumentWithStreamReader(){
// Create a DataSet with one table and two columns.
DataSet* OriginalDataSet = new DataSet(S"myDataSet");
OriginalDataSet->Namespace= S"NetFrameWork";
DataTable* myTable = new DataTable(S"myTable");
DataColumn* c1 = new DataColumn(S"id", Type::GetType(S"System.Int32"));
c1->AutoIncrement= true;
DataColumn* c2 = new DataColumn(S"item");
myTable->Columns->Add(c1);
myTable->Columns->Add(c2);
OriginalDataSet->Tables->Add(myTable);
// Add ten rows.
DataRow* newRow;
for(int i = 0; i < 10; i++){
newRow = myTable->NewRow();
newRow->Item[S"item"]= String::Format( S"item {0}", __box(i));
myTable->Rows->Add(newRow);
}
OriginalDataSet->AcceptChanges();
// Print out values of each table in the DataSet using the
// function defined below.
PrintValues(OriginalDataSet, S"Original DataSet");
// Write the schema and data to XML file with StreamWriter.
String* xmlFilename = S"myXmlDocument.xml";
// Create a new StreamWriter.
System::IO::StreamWriter* myStreamWriter =
new System::IO::StreamWriter(xmlFilename);
// Use WriteXml to write the document.
OriginalDataSet->WriteXml(myStreamWriter);
// Close the FileStream.
myStreamWriter->Close();
// Dispose of the original DataSet.
OriginalDataSet->Dispose();
// Create a new DataSet.
DataSet* newDataSet = new DataSet(S"New DataSet");
// Create a StreamReader to read the file.
System::IO::StreamReader* myStreamReader =
new System::IO::StreamReader(xmlFilename);
// Read the XML document into the DataSet.
newDataSet->ReadXml(myStreamReader);
// Close the StreamReader.
myStreamReader->Close();
// Print out values of each table in the DataSet using the
// function defined below.
PrintValues(newDataSet,S"New DataSet");
}
void PrintValues(DataSet* ds, String* label){
Console::WriteLine(S"\n{0}", label);
System::Collections::IEnumerator* myEnum = ds->Tables->GetEnumerator();
while (myEnum->MoveNext())
{
DataTable* t = __try_cast<DataTable*>(myEnum->Current);
Console::WriteLine(S"TableName: {0}", t->TableName);
System::Collections::IEnumerator* myEnum1 = t->Rows->GetEnumerator();
while (myEnum1->MoveNext())
{
DataRow* r = __try_cast<DataRow*>(myEnum1->Current);
System::Collections::IEnumerator* myEnum2 = t->Columns->GetEnumerator();
while (myEnum2->MoveNext())
{
DataColumn* c = __try_cast<DataColumn*>(myEnum2->Current);
Console::Write(S"\t {0}", r->Item[c] );
}
Console::WriteLine();
}
}
}
[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 .gif)
をクリックします。
必要条件
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
参照
DataSet クラス | DataSet メンバ | System.Data 名前空間 | DataSet.WriteXml オーバーロードの一覧 | ReadXml | ReadXmlSchema | WriteXml | WriteXmlSchema