Serializing Lists of Classes to XML

Just to check, have you marked Bar as [Serializable]?

Also, you need a parameter-less ctor on Bar, to deserialize

Hmm, I used:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {

        Foo f = new Foo();

        f.BarList = new List<Bar>();

        f.BarList.Add(new Bar { Property1 = "abc", Property2 = "def" });

        XmlSerializer ser = new XmlSerializer(typeof(Foo));

        using (FileStream fs = new FileStream(@"c:\sertest.xml", FileMode.Create))
        {
            ser.Serialize(fs, f);
        }
    }
}

public class Foo
{
    [XmlArray("BarList"), XmlArrayItem(typeof(Bar), ElementName = "Bar")]
    public List<Bar> BarList { get; set; }
}

[XmlRoot("Foo")]
public class Bar
{
    public string Property1 { get; set; }
    public string Property2 { get; set; }
}

And that produced:

<?xml version="1.0"?>
<Foo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <BarList>
    <Bar>
      <Property1>abc</Property1>
      <Property2>def</Property2>
    </Bar>
  </BarList>
</Foo>

Everything looks great. As @Carl said you need to add the [Serializable] attibute to your classes, but other than that your XML creation should work find.

Foo

[Serializable]
[XmlRoot("Foo")]
public class Foo
{
    [XmlArray("BarList"), XmlArrayItem(typeof(Bar), ElementName = "Bar")]
    public List<Bar> BarList { get; set; }
}

Bar

[Serializable]
public class Bar
{
    public string Property1 { get; set; }
    public string Property2 { get; set; }
}

Code to test

Foo f = new Foo();
f.BarList = new List<Bar>();
f.BarList.Add(new Bar() { Property1 = "s", Property2 = "2" });
f.BarList.Add(new Bar() { Property1 = "s", Property2 = "2" });

FileStream fs = new FileStream("c:\\test.xml", FileMode.OpenOrCreate);
System.Xml.Serialization.XmlSerializer s = new System.Xml.Serialization.XmlSerializer(typeof(Foo));
s.Serialize(fs, f);

Output

<?xml version="1.0" ?> 
<Foo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <BarList>
        <Bar>
            <Property1>s</Property1> 
            <Property2>2</Property2> 
        </Bar>
        <Bar>
            <Property1>s</Property1> 
            <Property2>2</Property2> 
        </Bar>
    </BarList>
</Foo>

var xmlfromLINQ = new XElement("BarList",
            from c in BarList 
            select new XElement("Bar",
                new XElement("Property1", c.Property1),
                new XElement("Property2", c.Property2)
             ));