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DataSet.WriteXml Method (TextWriter, XmlWriteMode)

Writes the current data, and optionally the schema, for the DataSet using the specified TextWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.

Namespace:  System.Data
Assembly:  System.Data (in System.Data.dll)

public void WriteXml(
	TextWriter writer,
	XmlWriteMode mode
)

Parameters

writer
Type: System.IO.TextWriter

A System.IO.TextWriter object used to write the document.

mode
Type: System.Data.XmlWriteMode

One of the XmlWriteMode values.

The WriteXml method provides a way to write either data only, or both data and schema from a DataSet into an XML document, whereas the WriteXmlSchema method writes only the schema. To write both data and schema, set the mode parameter to WriteSchema.

Note that the same is true for the ReadXml and ReadXmlSchema methods, respectively. To read XML data, or both schema and data into the DataSet, use the ReadXml method. To read just the schema, use the ReadXmlSchema method.

NoteNote

An InvalidOperationException will be thrown if a column type in the DataRow being read from or written to implements IDynamicMetaObjectProvider and does not implement IXmlSerializable.

The following example first creates a simple DataSet with one DataTable, two columns, and ten rows. The DataSet schema and data are written to disk by invoking the WriteXml method. A second DataSet is created and the ReadXml method is used to fill it with schema and data.

private void DemonstrateReadWriteXMLDocumentWithFileStream()
{
    // Create a DataSet with one table and two columns.
    DataSet originalDataSet = new DataSet("dataSet");
    DataTable table = new DataTable("table");
    DataColumn idColumn = new DataColumn("id", 
        Type.GetType("System.Int32"));
    idColumn.AutoIncrement= true;

    DataColumn itemColumn = new DataColumn("item");
    table.Columns.Add(idColumn);
    table.Columns.Add(itemColumn);
    originalDataSet.Tables.Add(table);
    // Add ten rows.

    DataRow newRow;
    for(int i = 0; i < 10; i++)
    {
        newRow = table.NewRow();
        newRow["item"]= "item " + i;
        table.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 FileStream. 
    string xmlFilename = "XmlDocument.xml";
    System.IO.FileStream streamWrite = new System.IO.FileStream
        (xmlFilename, System.IO.FileMode.Create);

    // Use WriteXml to write the XML document.
    originalDataSet.WriteXml(streamWrite);

    // Close the FileStream.
    streamWrite.Close();

    // Dispose of the original DataSet.
    originalDataSet.Dispose();
    // Create a new DataSet.
    DataSet newDataSet = new DataSet("New DataSet");

    // Read the XML document back in.  
    // Create new FileStream to read schema with.
    System.IO.FileStream streamRead = new System.IO.FileStream
        (xmlFilename,System.IO.FileMode.Open);
    newDataSet.ReadXml(streamRead);

    // Print out values of each table in the DataSet  
    // using the function defined below.
    PrintValues(newDataSet,"New DataSet");
}

private void PrintValues(DataSet dataSet, string label)
{
    Console.WriteLine("\n" + label);
    foreach(DataTable table in dataSet.Tables)
    {
        Console.WriteLine("TableName: " + table.TableName);
        foreach(DataRow row in table.Rows)
        {
            foreach(DataColumn column in table.Columns)
            {
                Console.Write("\table " + row[column] );
            }
            Console.WriteLine();
        }
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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