8.2. Saving and Loading a DataSet from XML

Problem

You need to save a DataSet as an XML file and create a DataSet from an XML file.

Solution

Use the XmlTextWriter and XmlTextReader classes.

The sample code contains three event handlers:

Write Button.Click

Creates a DataSet containing the Orders and Order Details tables from Northwind and a relation between the two tables. The XML schema and data for the DataSet is written both to a file and to a text box on the form.

Read Button.Click

Creates a DataSet and reads in schema and data from a file containing a previously serialized XML. The XML is written from the DataSet to a stream and displayed.

Clear Button.Click

Clears the data grid and the result text box.

The C# code is shown in Example 8-3.

Example 8-3. File: XmlFileForm.cs

// Namespaces, variables, and constants using System; using System.Configuration; using System.Windows.Forms; using System.Text; using System.IO; using System.Xml; using System.Xml.Schema; using System.Data; using System.Data.SqlClient; // Table name constants private const String ORDERS_TABLE = "Orders"; private const String ORDERDETAILS_TABLE = "OrderDetails"; // Relation name constants private const String ORDERS_ORDERDETAILS_RELATION = "Orders_OrderDetails_Relation"; // Field name constants private const String ORDERID_FIELD = "OrderID"; // . . . private void writeXmlButton_Click(object sender, System.EventArgs e) { DataSet ds = new DataSet( ); SqlDataAdapter da; // Fill the Order table and add it to the DataSet. ...

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