Im trying to create a button from code behind that has the same attributes as this:
<Button Content="Find Student" Tag="FindStudent" HorizontalAlignment="Right" x:Name="btnFindStudent" Click="btnGeneral_Click" />
Code behind:
Button btnFindStudent = new Button();
btnFindStudent.Click += this.btnGeneral_Click;
btnFindStudent.Name = Convert.ToString("btnFindStudent");
btnFindStudent.Tag = Convert.ToString("FindStudent");
btnFindStudent.Content = Convert.ToString("View");
btnFindStudent.HorizontalAlignment = HorizontalAlignment.Right;
btnFindStudent.Height = 20;
btnFindStudent.Width = 36;
The problem is when I click the button I get an error
Value cannot be null.
Parameter name: Children of 'System.Windows.Controls.UIElementCollection' cannot be null. Object derived from UIElement expected.
And im not quite sure whats missing, this is the full code:
public partial class FindStudent : UserControl
{
private Dictionary<string, UserControl> _userControls = new Dictionary<string, UserControl>();
public Dictionary<string, UserControl> GetUserControls()
{
return _userControls;
}
private static readonly Random rand = new Random();
public FindStudent()
{
InitializeComponent();
List<string> userControlKeys = new List<string>();
userControlKeys.Add("FindStudent");
Type type = this.GetType();
Assembly assembly = type.Assembly;
foreach (string userControlKey in userControlKeys)
{
string userControlFullName = String.Format("{0}.AppPages.{1}", type.Namespace, userControlKey);
UserControl userControl = (UserControl)assembly.CreateInstance(userControlFullName);
_userControls.Add(userControlKey, userControl);
}
for (int i = 1; i <= 10; i++)
{
Button btnFindStudent = new Button();
btnFindStudent.Click += this.btnGeneral_Click;
btnFindStudent.Name = Convert.ToString("btnFindStudent");
btnFindStudent.Tag = Convert.ToString("FindStudent");
btnFindStudent.Content = Convert.ToString("View {0}", i);
btnFindStudent.HorizontalAlignment = HorizontalAlignment.Right;
btnFindStudent.Height = 20;
btnFindStudent.Width = 36;
StackPanel stackPanel = new StackPanel();
stackPanel.Children.Add(btnFindStudent);
MainArea.Children.Add(stackPanel);
}
}
private void btnGeneral_Click(object sender, RoutedEventArgs e)
{
PanelMainContent.Children.Clear();
Button button = (Button)e.OriginalSource;
Type type = this.GetType();
Assembly assembly = type.Assembly;
PanelMainContent.Children.Add(_userControls[button.Tag.ToString()]);
// error on above line.
}
}
Xaml:
<UserControl x:Class="WpfApplication4.AppPages.FindStudent"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<DockPanel HorizontalAlignment="Stretch" >
<ScrollViewer VerticalScrollBarVisibility="Hidden">
<DockPanel x:Name="PanelMainWrapper" Margin="10,20,0,0">
<DockPanel x:Name="PanelMainContent" HorizontalAlignment="Stretch" VerticalAlignment="Top" Margin="0,30,0,0">
<ScrollViewer VerticalScrollBarVisibility="Hidden">
<WrapPanel x:Name="MainArea" VerticalAlignment="Bottom" HorizontalAlignment="Left">
</WrapPanel>
</ScrollViewer>
</DockPanel>
</DockPanel>
</ScrollViewer>
</DockPanel>
</UserControl>
It should just reload the page I am currently using and I can set the appPage at a later date, but it doesnt want to play ball. This works in my main window just not on my control but I dont set the button from code behind I use the xaml I first mention in my main window. Which tells me I am missing something from button click (I think is set correct), tag is set correctly but I am not sure name will be x:Name like my xaml code.
Although your code really confuses me, here is what isn't working. Your constructing a fully qualified type name by
String.Format("{0}.AppPages.{1}", type.Namespace, userControlKey)
where type.Namespace
already contains the complete namespace of the type in question and hence the "AppPages" part is needless. Instead, you should write
String.Format("{0}.{1}", type.Namespace, userControlKey)
And why not simply do
assembly.CreateInstance(type.FullName);
when you only want to create a new instance of FindStudent
(which i guess is what you want to do).