Question

My code crashes when using the XmlWriter, saying it is used by another process.

    private void generateXml(Control receivedControl)
    {
        foreach (Control subCtrl in receivedControl.Controls)
        {
            using (XmlWriter writer = XmlWriter.Create("C:\\ui.xml"))
            {
                writer.WriteStartElement(subCtrl.Name);
                generateXml(subCtrl);
                writer.WriteEndElement();
            }
        }
    }

    private void button2_Click(object sender, EventArgs e)
    {
        foreach (Control c in this.Controls)
        {
            generateXml(c);
        }
    }

Here’s the error I get debugging:

Additional information: The process cannot access the file ‘C:\ui.xml’ because it is being used by another process.

EDIT: So thanks to you I’ve managed to get the recursion working, but it only writes the last object in the xml file, anybody knows why? Here’s the updated code:

    private void generateXml(XmlWriter receivedWriter, Control receivedControl)
    {
        receivedWriter.WriteStartElement(receivedControl.Name);
        foreach (Control subCtrl in receivedControl.Controls)
        {
            generateXml(receivedWriter, subCtrl);
        }
        receivedWriter.WriteEndElement();
    }
    private void button2_Click(object sender, EventArgs e)
    {
        foreach (Control c in this.Controls)
        {
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.Indent = true;

            using(XmlWriter writer = XmlWriter.Create("c:\\ui.xml", settings))
            {
                writer.WriteStartDocument();
                writer.WriteStartElement("Form");
                generateXml(writer, c);
                writer.WriteEndElement();
                writer.WriteEndDocument();
            }
        }
    }

Answer 1

The file when accessed by the XmlWriter will become locked, so an subsequent attempts to read it result in error.

You can change the function to pass the writer as a parameter, thereby have one copy and hopefully avoid the issue.

private void generateXml(XmlWriter writer, Control receivedControl)
{
    foreach (Control subCtrl in receivedControl.Controls)
    {
            writer.WriteStartElement(subCtrl.Name);
            generateXml(writer, subCtrl);
            writer.WriteEndElement();
    }
}

private void button2_Click(object sender, EventArgs e)
{
    using (XmlWriter writer = XmlWriter.Create("C:\\ui.xml"))
    {
        writer.WriteStartDocument();
        writer.WriteStartElement(this.Name); // This is the document element
        foreach (Control c in this.Controls)
        {
            generateXml(writer, c);
        }
        writer.WriteEndDocument(); // Close any open tags
    }
}

Above is a sample – not tested.

Edit : Updated to include root element