Hi All,

Been trying to create a custom datatype which contains two textbox controls and a content picker.

My starting poiint was the excellent video 'create a custom datatype using the umbraco usercontrol wrapper.'  This part works fine.  But from here I've added the content picker which is rendering correctly.  However when I try and save the page a 'value cannot be null' error is displayed.

The code I have is:

 public partial class LinkBox : System.Web.UI.UserControl, umbraco.editorControls.userControlGrapper.IUsercontrolDataEditor
    {
        ContentPicker mp = new ContentPicker();

        protected void Page_Load(object sender, EventArgs e)
        {
            ContentPicker mp = new ContentPicker();
            mp.AppAlias = "media";
            mp.TreeAlias = "media";
            mp.ID = "mediaPicker";

            mediaPickerPlaceHolder.Controls.Add(mp);
        
        }

        #region IUsercontrolDataEditor Members

        public object value
        {
            get
            {
                XDocument values = new XDocument(
                    new XElement("textBoxes",
                        new XElement("textBox",
                            new XAttribute("id", linkText.ID),
                            new XElement("value", new XCData(linkText.Text))
                        ),
                        new XElement("textBox",
                            new XAttribute("id", linkUrl.ID),
                            new XElement("value", new XCData(linkUrl.Text))
                        )
                    ),
                    new XElement("mediaNode",
                        new XAttribute("id", mp.ID),
                        new XElement("value", new XCData(mp.Value))
                    )
                );
                return values.ToString();
            }
            set
            {
                if (value != null)
                {
                    try
                    {
                        XDocument savedValues = XDocument.Parse(value.ToString());
                        IEnumerable<TextBox> textBoxes = linkPanel.Controls.OfType<TextBox>();
                        foreach (TextBox textBox in textBoxes)
                        {
                            string inputId = textBox.ID;
                            var vstr = (from xml in savedValues.Descendants("textBox") where xml.Attribute("id").Value == inputId select xml).Single().Element("value").Value;
                            textBox.Text = vstr;
                        }
                        IEnumerable<ContentPicker> contentPickers = mediaPickerPlaceHolder.Controls.OfType<ContentPicker>();
                        foreach (ContentPicker contentPicker in contentPickers)
                        {
                            string inputId = contentPicker.ID;
                            var mvstr = (from xml in savedValues.Descendants("mediaNode") where xml.Attribute("id").Value == inputId select xml).Single().Element("value").Value;
                            contentPicker.Value = mvstr;
                        }
                    }
                    catch (System.Xml.XmlException e)
                    {
                        //No root node element
                    }
                }
            }
        }

        #endregion

Would be grateful if someone could point me in the right direction.

Thanks,

Eddie