[Solved] Using AlignmentContentPresenter - XamlParseException - Element is already the child of another element

[Rick Glos]

Hi there,

I'm attempting to refactor my original code to use the new AlignmentContentPresenter.

Here's a link to our old discussion.

As a quick recap, I'm dynamically creating the columns because users are defining 'views' dynamically - picking and choosing which columns are in the GridView.  Here's some link to our old discussions (dynamic columns & binding to an object built at run-time) I used to get it working.

Anyway...

I'm receiving an error with the message of "Element is already the child of another element."

I've been trying to troubleshoot this.  It's a strange one because if I just set the Header property it works fine.  The problem occurs only when I start using the AlignmentContentPresenter.  Then, when using the AlignmentContentPresenter, if I create the columns dynamically via the constructor it works fine but if I create the columns outside the constructor I get the error.

        public MainPage()
        {
            InitializeComponent();

            List<Person> people = new List<Person>();
            people.Add(new Person() { Name = "Joe Bob", Age = 37 });
            people.Add(new Person() { Name = "Johnny Lunchbox", Age = 25 });
            people.Add(new Person() { Name = "Jim Beam", Age = 25 });
            this.DataContext = people;

            // If I call CreateColumns() here it works hmm... but via the click event on the button it does not
            // CreateColumns()
        }

        private void CreateColumns()
        {
            // TODO: Simulate a long running process

            //Dispatcher.BeginInvoke(() => { uxRadGridView.Columns.Add(CreateColumn("Name", "Name 1", "This is the Name 1 column.")); });
            for (int i = 1; i < 26; i++)
            {
                uxRadGridView.Columns.Add(CreateColumn("Name", "Name " +  i, "This is the Name " + i + " column."));
                // This is where the XamlParseException will occur
                uxRadGridView.Columns.Add(CreateColumn("Age", "Age " + i, "This is the Age " + i + " column."));
            }
        }

        private GridViewColumn CreateColumn(string uniqueName, string headerText, string toolTipText)
        {
            GridViewDataColumn column = new GridViewDataColumn();
            column.UniqueName = uniqueName;

            //// This work either way - via button or constructor
            //column.Header = headerText;

            // This only works if CreateColumns() is called in the constructor
            AlignmentContentPresenter alignmentContentPresenter = new AlignmentContentPresenter();
            alignmentContentPresenter.TextWrapping = TextWrapping.Wrap;
            alignmentContentPresenter.Content = headerText;
            column.Header = alignmentContentPresenter;
            ToolTipService.SetToolTip(alignmentContentPresenter, toolTipText);

            return column;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            CreateColumns();
        }

        public class Person
        {
            public string Name { get; set; }
            public int Age { get; set; }
        }

I've created a sample to demonstrate the error.  Launch it and click on 'Create Columns' and you'll get the error.  Uncomment the line in the constructor and it works.  It also works if I comment out the block around the AlignmentContentPresenter.

Is this a bug with my code?  Am I using the AlignmentContentPresenter incorrectly?  I am hoping to use it to simplify my old code and add tool tips to the column headers.

Thanks!

[Pavel Pavlov]

Hi Rick,

This week we have fixed a problem related to this exception. When you place an UIElement within the header template, in specific scenarios it gave such exception.

I believe the problem is fixed now. Please give the latest internal build a try and let me know if you still have a trouble. ( You should have the binaries available for download in your Client.NET account).

In case you have any further problems, just let me know  and we will provide a fix as soon as possible.

Regards,
Pavel Pavlov
the Telerik team

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[Rick Glos]

The latest internal build, RadControls_for_Silverlight_2009_2_0911_Dev, fixed the problem.

Thank you.