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selected value cannot be set

I have a combobox which gets its Items from some scan function.
If the user select an element, in the next time, the user's chosen item should be selected (if it is present on the scan function output). The problem is that I cannot select it.
Here is the declaration of the ComboBox:
<ComboBox Grid.Column="1" Grid.Row="0" Margin="5" Name="SerialPortNames" Text="{Binding Name}" IsEditable="False"/>
and here what I have tried so far:
private void Window_Loaded(object sender, RoutedEventArgs e)
{
string portNameSetting = Settings.Default["SerialPortName"].ToString();
SerialPortNames.ItemsSource = SerialPort.GetPortNames();
foreach (string SerialPortNameItem in SerialPortNames.Items)
{
if (SerialPortNameItem == portNameSetting)
{
SerialPortNames.Text = SerialPortNameItem; // why this is not working
break;
}
}
}
by debugging this, I get the item selected in the combobox, but it seems that something override it and it is empty!

In your code you Binded the Text propery and also setting it from code behind
Remove Text="{Binding Name}" from the combobox
<ComboBox Width="200" Height="200" Grid.Column="1" Grid.Row="0" Margin="5" Name="SerialPortNames" IsEditable="False"/>

ListBox filled with binding doesn't select item on click

I'm trying to use a ListBox to choose an entry and then display a picture belonging to this selected entry. But just at the beginning I got my first problem: filling the ListBox with binding is working, but if I click on one line in my running program, it doesn't select the line. I can just see the highlighted hover effect, but not select a line. Any ideas what my mistake could be?
This is my XAML:
<ListBox x:Name="entrySelection" ItemsSource="{Binding Path=entryItems}" HorizontalAlignment="Left" Height="335" Margin="428,349,0,0" VerticalAlignment="Top" Width="540" FontSize="24"/>
And in MainWindow.xaml.cs I'm filling the ListBox with entries:
private void fillEntrySelectionListBox()
{
//Fill listBox with entries for active user
DataContext = this;
entryItems = new ObservableCollection<ComboBoxItem>();
foreach (HistoryEntry h in activeUser.History)
{
var cbItem = new ComboBoxItem();
cbItem.Content = h.toString();
entryItems.Add(cbItem);
}
this.entrySelection.ItemsSource = entryItems;
labelEntrySelection.Text = "Einträge für: " + activeUser.Id;
//show image matching the selected entry
if (activeUser.History != null)
{
int index = entrySelection.SelectedIndex;
if (index != -1 && index < activeUser.History.Count)
{
this.entryImage.Source = activeUser.History[index].Image;
}
}
}
So I can see my ListBox correctly filled, but not select anything - so I can't go on with loading the picture matching the selected entry.
I'm still quite new to programming, so any help would be great :)
EDIT: If someone takes a look at this thread later: here's the - quite obvious -solution
XAML now looks like this
<ListBox x:Name="entrySelection" ItemsSource="{Binding Path=entryItems}" HorizontalAlignment="Left" Height="335" Margin="428,349,0,0" VerticalAlignment="Top" Width="540" FontFamily="Siemens sans" FontSize="24">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Text}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Code behind to fill it:
//Fill listbox with entries for selected user
DataContext = this;
entryItems = new ObservableCollection<DataItem>();
foreach (HistoryEntry h in selectedUser.History)
{
var lbItem = new DataItem(h.toString());
entryItems.Add(lbItem);
}
this.entrySelection.ItemsSource = entryItems;
labelEntrySelection.Text = "Einträge für: " + selectedUser.Id;
And new Class DataItem:
class DataItem
{
private String text;
public DataItem(String s)
{
text = s;
}
public String Text
{
get
{
return text;
}
}
}

You are filling it with ComboBoxItem, which is not relevant to the ListBox, and also wrong by definition.
You need to have the ObservableCollection filled with data items.
Meaning, make a class that contains the data you want to store, and the ListBox will generate a ListBoxItem automatically per data item.
http://www.wpf-tutorial.com/list-controls/listbox-control/

Handling WPF Editable combobox when entered text is not a part of datsource

I have a Combobox in WPF, I have set Is Editable="true" which allows me enter any text in the combobox. I would like to restrict users from entering text outside datasource.
Xaml:
<ComboBox Name="service" Margin="0,0,0,4"
IsEditable="True"
Grid.Column="1"
Grid.ColumnSpan="2" Grid.Row="4"
SelectedValuePath="Id"
DisplayMemberPath="Service"
SelectedValue="{Binding Controller.Service1}"
ItemsSource="{Binding}" />
C#:
System.Data.DataView vw = tableAdapterServices.GetData().DefaultView;
service.ItemsSource = vw;
service.SelectedIndex = 0;
I do not want to allow users to enter text which is not present in the datasource, or handle it if the user enters any other text.
Update:
Thanks for the solution #Vishal, LostFocus event is handling the issue, but it gave rise to another issue. I have a button which is used to submit the combobox value along with other textbox values to the server. I am setting default value in the combobox in lostfocus event. But I need to prevent the button click event if some value other that datasource value is added in combobox.

You can check for selectedIndex in Lostfocus event :
private void ComboBox_LostFocus(object sender, EventArgs e)
{
if(((ComboBox)sender).SelectedIndex == -1)
{
//Text entered by user is not a part your ItemsSource's Item
SaveButton.IsEnabled = false;
}
else
{
//Text entered by user is a part your ItemsSource's Item
SaveButton.IsEnabled = true;
}
}

You can try handling the ComboBox's TextInput or PreviewTextInput events, doing the text search yourself, selecting the most appropriate item, and setting "e.Handled = true."
This works for a single character (i.e. if you enter the letter "j", it will select the first item that contains a "j" or "J"), but I'm sure there's a way to do this with your control. Just include a little more logic to achieve this.
private void MyComboBox_PreviewTextInput(object sender, TextCompositionEventArgs e) {
foreach (ComboBoxItem i in MyComboBox.Items) {
if (i.Content.ToString().ToUpper().Contains(e.Text.ToUpper())) {
MyComboBox.SelectedItem = i;
break;
}
}
e.Handled = true;
}

Ok, from what I understand the behaviour of the combobox should disregard an inserted character if there is no item in the datasource that contains the resulted string.
I believe you are doing it in a MVVM style since you are using binding. What you can do is to bind the ComboBox text to a property and the PreviewTextInput event to a command and do the filtering there.
XAML:
<ComboBox Name="service"
Margin="0,0,0,4"
IsEditable="True"
Grid.Column="1"
Grid.ColumnSpan="2"
Grid.Row="4"
SelectedValuePath="Id"
DisplayMemberPath="Service"
SelectedValue="{Binding Controller.Service1}"
ItemsSource="{Binding}"
Text="{Binding Text, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
>
<i:Interaction.Triggers>
<i:EventTrigger EventName="PreviewTextInput">
<cmd:EventToCommand Command="{Binding TextInputCommand}" PassEventArgsToCommand="True" />
</i:EventTrigger>
</i:Interaction.Triggers>
</Combobox>
C# ViewModel:
public RelayCommand<object> TextInputCommand { get; set; }
public bool CanExecuteTextInputCommand(object param)
{
return true;
}
public void ExecuteTextInputCommand(object param)
{
TextCompositionEventArgs e = param as TextCompositionEventArgs;
string currentText = this.Text;
string entireText = string.Format("{0}{1}", currentText, e.Text);
var item = this.Items.Where(d => d.StartsWith(entireText)).FirstOrDefault();
if (item == null)
{
e.Handled = true;
this.Text = currentText;
}
}
Where Items is the ObservableCollection containing the items (in this case it's a list of strings) and Text is the property binded to the Combobox text.
EDIT: Ok so what you need to do to make it work is to go to your project, right click on References, choose Manage NuGet Packages, search and install MVVM Light. Two dlls that start with GalaSoft will be added to your references. After this, in your xaml code add these namespaces:
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.WPF4"
What this allows you to do is to bind an event to a ICommand object.

Preselect Value of Treeview inside combobox

I am looking to implement a treeview inside a combobox. Basically I want it to show as a combobox when collapsed but a treeview inside combo box when expanded. When a user clicks on a node, I want it to show in the collapsed combo box. I have got this working so far.
The problem I am having is that how do I show a default value from c# when this combo box is loaded. Please help guys as I am running out of ideas :)
Thanks in advance.
Data Template
<DataTemplate x:Key="TreeViewExpanded" >
<StackPanel>
<TreeView x:Name="DPointTree" Margin="5" ItemsSource="{Binding Datapoint}"
Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ComboBox}}}"
>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Field}">
<TextBlock Text="{Binding Name}"/>
<HierarchicalDataTemplate.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}"/>
</DataTemplate>
</HierarchicalDataTemplate.ItemTemplate>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
</StackPanel>
<DataTemplate.Triggers>
<DataTrigger Binding = "{Binding Path=SelectedFieldName, Mode=TwoWay}" Value = "">
<Setter Property = "Visibility" Value = "Collapsed"/>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
Here is the Xaml
<ComboBox Name="cmbFieldName" Width="150" Background="White" ItemsSource="{Binding}" SelectedItem="{Binding SelectedFieldName , Mode=TwoWay}" >
<ComboBox.ItemTemplateSelector>
<local:TreeViewSelector/>
</ComboBox.ItemTemplateSelector>
</ComboBox>
Here is the DataSet passed to this.
Datapoint _datapoint2 = new Datapoint();
_datapoint2.Name = "Alpha";
_datapoint2.FieldID.Add("Contains Elements");
_datapoint2.Field.Add("1 Year");
_datapoint2.Field.Add("2 Year");
_datapoint2.Field.Add("3 Year");

Try this:
private void TreeView_Loaded(object sender, RoutedEventArgs e)
{
TreeView areaTreeView = sender as TreeView;
// Expand the treeview
if (areaTreeView != null)
{
ExpandCollapseTreeNodes(areaTreeView, true);
}
}
public static void ExpandCollapseTreeNodes(ItemsControl parentContainer, bool isExpanded)
{
foreach (Object item in parentContainer.Items)
{
TreeViewItem currentContainer = parentContainer.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;
if (currentContainer != null) // && currentContainer.Items.Count > 0
{
//expand the item
currentContainer.IsExpanded = isExpanded;
//if the item's children are not generated, they must be expanded
if (isExpanded && currentContainer.ItemContainerGenerator.Status != GeneratorStatus.ContainersGenerated)
{
//store the event handler in a variable so we can remove it (in the handler itself)
EventHandler eh = null;
eh = new EventHandler(delegate
{
//once the children have been generated, expand those children's children then remove the event handler
if (currentContainer.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
{
ExpandCollapseTreeNodes(currentContainer, isExpanded);
currentContainer.ItemContainerGenerator.StatusChanged -= eh;
}
});
currentContainer.ItemContainerGenerator.StatusChanged += eh;
}
//otherwise the children have already been generated, so we can now expand those children
else
{
ExpandCollapseTreeNodes(currentContainer, isExpanded);
}
}
}
}

it is not pretty but works to select a node in the tree
// in code behind after the tree is declared, e.g. after InitializeComponent();
SynchronizationContext.Current.Post(delegate
{
// expand the tree to the selected node after loading
treeView.ExpandAll(); // or if path is known treeView.ExpandPath(...);
SynchronizationContext.Current.Post(delegate
{
treeView.GetContainerFromItem(root.Children[0]).IsSelected = true;
}, null);
}, null);

DataGridCheckBox initialize to all checked

I'm using .Net 3.5 with WPF and XAML.
I have a datagrid with the first column being a DataGridCheckBoxColumn.
This is inside of a window popup.
In the constructor, I sometimes want to initialize all rows to be selected, and other cases no rows to be selected.
Using data binding, I can initialize the checkbox on a row to either checked or not checked.
But I can't get the header checkbox checked along with all the checks on the rows in the case when all rows are to be checked. How can I get to the checkbox?
<toolkit:DataGridCheckBoxColumn CellStyle="{StaticResource SingleClickEditing}" Visibility="{Binding exists}" Binding="{Binding Path=toTransfer, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" IsReadOnly="False">
<toolkit:DataGridCheckBoxColumn.HeaderTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox Checked="CheckBox_Checked" Unchecked="CheckBox_Checked"/>
</StackPanel>
</DataTemplate>
</toolkit:DataGridCheckBoxColumn.HeaderTemplate>
</toolkit:DataGridCheckBoxColumn>
I'm doing something like:
public MyPopupWindow()
{
InitializeComponent();
if(checkMode.Equals("all"))
{
// Check all the items
foreach (var item in bindList)
{
item.toTransfer = true;
}
// How to check the header checkbox?
}

I'm not sure if this is the best way to do this but you can do
<CheckBox Checked="CheckBox_Checked" Unchecked="CheckBox_Checked" Loaded="CheckBox_Loaded"/>
and
void CheckBox_Loaded(object sender, RoutedEventArgs e)
{
CheckBox checkBox = sender as CheckBox;
if(checkMode.Equals("all"))
{
checkBox.IsChecked = true;
}
}