DataTable.WriteXml Method

Writes the current contents of the DataTable as XML.

This member is overloaded. For complete information about this member, including syntax, usage, and examples, click a name in the overload list.

  Name Description
Public method WriteXml(Stream) Writes the current contents of the DataTable as XML using the specified Stream.
Public method WriteXml(String) Writes the current contents of the DataTable as XML using the specified file.
Public method WriteXml(TextWriter) Writes the current contents of the DataTable as XML using the specified TextWriter.
Public method WriteXml(XmlWriter) Writes the current contents of the DataTable as XML using the specified XmlWriter.
Public method WriteXml(Stream, Boolean) Writes the current contents of the DataTable as XML using the specified Stream. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
Public method WriteXml(Stream, XmlWriteMode) Writes the current data, and optionally the schema, for the DataTable to the specified file using the specified XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Public method WriteXml(String, Boolean) Writes the current contents of the DataTable as XML using the specified file. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
Public method WriteXml(String, XmlWriteMode) Writes the current data, and optionally the schema, for the DataTable using the specified file and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Public method WriteXml(TextWriter, Boolean) Writes the current contents of the DataTable as XML using the specified TextWriter. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
Public method WriteXml(TextWriter, XmlWriteMode) Writes the current data, and optionally the schema, for the DataTable using the specified TextWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Public method WriteXml(XmlWriter, Boolean) Writes the current contents of the DataTable as XML using the specified XmlWriter.
Public method WriteXml(XmlWriter, XmlWriteMode) Writes the current data, and optionally the schema, for the DataTable using the specified XmlWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema.
Public method WriteXml(Stream, XmlWriteMode, Boolean) Writes the current data, and optionally the schema, for the DataTable to the specified file using the specified XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
Public method WriteXml(String, XmlWriteMode, Boolean) Writes the current data, and optionally the schema, for the DataTable using the specified file and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
Public method WriteXml(TextWriter, XmlWriteMode, Boolean) Writes the current data, and optionally the schema, for the DataTable using the specified TextWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
Public method WriteXml(XmlWriter, XmlWriteMode, Boolean) Writes the current data, and optionally the schema, for the DataTable using the specified XmlWriter and XmlWriteMode. To write the schema, set the value for the mode parameter to WriteSchema. To save the data for the table and all its descendants, set the writeHierarchy parameter to true.
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The WriteXml method provides a way to write either data only, or both data and schema from a DataTable into an XML document, whereas the WriteXmlSchema method writes only the schema. To write both data and schema, use one of the overloads that include the XmlWriteMode parameter, and set its value 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 DataTable, use the ReadXml method. To read just the schema, use the ReadXmlSchema method.

Note Note

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 console application creates two DataTable instances, adds each to a DataSet, creates a DataRelation relating the two tables, and then uses the WriteXml method to write the data contained within the parent table to a TextWriter. The example demonstrates the behavior when setting the writeHierarchy parameter to each of its values.

Note Note

This example shows how to use one of the overloaded versions of WriteXml. For other examples that might be available, see the individual overload topics.

static void Main()
{
    DataSet ds = new DataSet();
    DataTable customerTable = GetCustomers();
    DataTable orderTable = GetOrders();

    ds.Tables.Add(customerTable);
    ds.Tables.Add(orderTable);
    ds.Relations.Add("CustomerOrder",
        new DataColumn[] { customerTable.Columns[0] },
        new DataColumn[] { orderTable.Columns[1] }, true);

    System.IO.StringWriter writer = new System.IO.StringWriter();
    customerTable.WriteXml(writer, XmlWriteMode.WriteSchema, false);
    PrintOutput(writer, "Customer table, without hierarchy");

    writer = new System.IO.StringWriter();
    customerTable.WriteXml(writer, XmlWriteMode.WriteSchema, true);
    PrintOutput(writer, "Customer table, with hierarchy");

    Console.WriteLine("Press any key to continue.");
    Console.ReadKey();
}

private static DataTable GetCustomers()
{
    // Create sample Customers table, in order 
    // to demonstrate the behavior of the DataTableReader.
    DataTable table = new DataTable();

    // Create two columns, ID and Name.
    DataColumn idColumn = table.Columns.Add("ID", typeof(System.Int32));
    table.Columns.Add("Name", typeof(System.String));

    // Set the ID column as the primary key column.
    table.PrimaryKey = new DataColumn[] { idColumn };

    table.Rows.Add(new object[] { 1, "Mary" });
    table.Rows.Add(new object[] { 2, "Andy" });
    table.Rows.Add(new object[] { 3, "Peter" });
    table.Rows.Add(new object[] { 4, "Russ" });
    table.AcceptChanges();
    return table;
}

private static DataTable GetOrders()
{
    // Create sample Customers table, in order 
    // to demonstrate the behavior of the DataTableReader.
    DataTable table = new DataTable();

    // Create three columns; OrderID, CustomerID, and OrderDate.
    table.Columns.Add(new DataColumn("OrderID", typeof(System.Int32)));
    table.Columns.Add(new DataColumn("CustomerID", typeof(System.Int32)));
    table.Columns.Add(new DataColumn("OrderDate", typeof(System.DateTime)));

    // Set the OrderID column as the primary key column.
    table.PrimaryKey = new DataColumn[] { table.Columns[0] };

    table.Rows.Add(new object[] { 1, 1, "12/2/2003" });
    table.Rows.Add(new object[] { 2, 1, "1/3/2004" });
    table.Rows.Add(new object[] { 3, 2, "11/13/2004" });
    table.Rows.Add(new object[] { 4, 3, "5/16/2004" });
    table.Rows.Add(new object[] { 5, 3, "5/22/2004" });
    table.Rows.Add(new object[] { 6, 4, "6/15/2004" });
    table.AcceptChanges();
    return table;
}

private static void PrintOutput(System.IO.TextWriter writer, string caption)
{
    Console.WriteLine("==============================");
    Console.WriteLine(caption);
    Console.WriteLine("==============================");
    Console.WriteLine(writer.ToString());
}

The example displays the following output in the console window:

==============================
Customer table, without hierarchy
==============================
<NewDataSet>
  <xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema
" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
    <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:MainDataTable="Table1">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="Table1">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="ID" type="xs:int" />
                <xs:element name="Name" type="xs:string" minOccurs="0" />
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:complexType>
      <xs:unique name="Constraint1" msdata:PrimaryKey="true">
        <xs:selector xpath=".//Table1" />
        <xs:field xpath="ID" />
      </xs:unique>
    </xs:element>
  </xs:schema>
  <Table1>
    <ID>1</ID>
    <Name>Mary</Name>
  </Table1>
  <Table1>
    <ID>2</ID>
    <Name>Andy</Name>
  </Table1>
  <Table1>
    <ID>3</ID>
    <Name>Peter</Name>
  </Table1>
  <Table1>
    <ID>4</ID>
    <Name>Russ</Name>
  </Table1>
</NewDataSet>
==============================
Customer table, with hierarchy
==============================
<NewDataSet>
  <xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema
" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
    <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:MainDataTable="Table1">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="Table1">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="ID" type="xs:int" />
                <xs:element name="Name" type="xs:string" minOccurs="0" />
              </xs:sequence>
            </xs:complexType>
          </xs:element>
          <xs:element name="Table2">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="OrderID" type="xs:int" />
                <xs:element name="CustomerID" type="xs:int" minOccurs="0" />
                <xs:element name="OrderDate" type="xs:dateTime" minOccurs="0" />

              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:complexType>
      <xs:unique name="Constraint1" msdata:PrimaryKey="true">
        <xs:selector xpath=".//Table1" />
        <xs:field xpath="ID" />
      </xs:unique>
      <xs:unique name="Table2_Constraint1" msdata:ConstraintName="Constraint1" m
sdata:PrimaryKey="true">
        <xs:selector xpath=".//Table2" />
        <xs:field xpath="OrderID" />
      </xs:unique>
      <xs:keyref name="CustomerOrder" refer="Constraint1">
        <xs:selector xpath=".//Table2" />
        <xs:field xpath="CustomerID" />
      </xs:keyref>
    </xs:element>
  </xs:schema>
  <Table1>
    <ID>1</ID>
    <Name>Mary</Name>
  </Table1>
  <Table1>
    <ID>2</ID>
    <Name>Andy</Name>
  </Table1>
  <Table1>
    <ID>3</ID>
    <Name>Peter</Name>
  </Table1>
  <Table1>
    <ID>4</ID>
    <Name>Russ</Name>
  </Table1>
  <Table2>
    <OrderID>1</OrderID>
    <CustomerID>1</CustomerID>
    <OrderDate>2003-12-02T00:00:00.0000000-08:00</OrderDate>
  </Table2>
  <Table2>
    <OrderID>2</OrderID>
    <CustomerID>1</CustomerID>
    <OrderDate>2004-01-03T00:00:00.0000000-08:00</OrderDate>
  </Table2>
  <Table2>
    <OrderID>3</OrderID>
    <CustomerID>2</CustomerID>
    <OrderDate>2004-11-13T00:00:00.0000000-08:00</OrderDate>
  </Table2>
  <Table2>
    <OrderID>4</OrderID>
    <CustomerID>3</CustomerID>
    <OrderDate>2004-05-16T00:00:00.0000000-07:00</OrderDate>
  </Table2>
  <Table2>
    <OrderID>5</OrderID>
    <CustomerID>3</CustomerID>
    <OrderDate>2004-05-22T00:00:00.0000000-07:00</OrderDate>
  </Table2>
  <Table2>
    <OrderID>6</OrderID>
    <CustomerID>4</CustomerID>
    <OrderDate>2004-06-15T00:00:00.0000000-07:00</OrderDate>
  </Table2>
</NewDataSet>
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