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I need to get attribute of listbox selecteditem wpf

I have that listbox: my bind is ProdutoGrupoViewModel, and list named as ListBoxGrupos
<ListBox HorizontalAlignment="x:Name="ListBoxGrupos"
ItemsSource="{Binding ProdutoGrupoViewModel}"
SelectionChanged="ListBoxGrupos_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate x:Name="ListViewGrupos">
<StackPanel>
<TextBlock Text="{Binding Descricao}"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
and when i get on my xaml.cs the property ListBoxGrupos.selectedItem, that returns for me an object
that object have some attributes
Obj.Descricao = "Pizzas"
Obj.GrupoCor = "FF8040"
Obj.GrupoID = 3
Obj.Image = "..."
Obj.Position = "0" ```
(i tried to upload the image of that obj, but need reputation, so i tried to explain)
i want to know how can i get the attribute GrupoID.

You need to cast the object to specified class
Grupo gru = (Grupo)ListBoxGrupos.SelectedItem;
gru.GrupoID = 3;

TextBlock with text highlighting

Faced the need to select a fragment of text in TextBlock, namely certain keywords on which the ListBox was filtered, this text block itself and containing
XAML variant, title property is not bound
<ListBox Name="ProcedureList" ItemsSource="{Binding Path=ProceduresView.View}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Name="ProcedurePanel" PreviewMouseDown="ProcedurePanel_OnPreviewMouseDown">
<DockPanel Width="{c:Binding ElementName=MainPanel, Path=Width-40}">
<!--<TextBlock Name="MainText" TextWrapping="Wrap" FontSize="16" Text="{Binding Path=title}" HorizontalAlignment="Left" />-->
<htb:HighlightTextBlock Name="MainText" TextWrapping="Wrap" FontSize="16" Text="{Binding Path=title}" HorizontalAlignment="Left">
<htb:HighlightTextBlock.HighlightRules>
<htb:HighlightRule
IgnoreCase="{Binding IgnoreCase, Source={StaticResource SourceVm}}"
HightlightedText="{Binding Path=title, Converter={StaticResource getFilter}}">
<htb:HighlightRule.Highlights>
<htb:HighlightBackgroung Brush="Yellow"/>
</htb:HighlightRule.Highlights>
</htb:HighlightRule>
</htb:HighlightTextBlock.HighlightRules>
</htb:HighlightTextBlock>
</DockPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
A component written by our compatriot with open source is used
Component
Description of component
The commented code is an old TexBlock with no selection
The new HighlightTextBlock component perfectly selects the text if you use a static resource, as in the example, but when I try to bind it to the current text it can not find this field :(, I'm new in WPF help figure it out
HightlightedText="{Binding Path=title, Converter={StaticResource getFilter}}"
How correctly to anchor this property to title?
DataContext structure
public ObservableCollection<Procedure> Procedures { set; get; }
public CollectionViewSource ProceduresView { set; get; } = new CollectionViewSource();
....
Procedures = new ObservableCollection<Procedure>();
ProceduresView.Filter += Procedures_Filter;
ProceduresView.Source = Procedures;
....
public class Procedure : ObservableObject
{
....
public String title { get; set; }
....
}
....
// Simple filtering
void Procedures_Filter(object sender, FilterEventArgs e)
{
Procedure procedure = (Procedure) e.Item;
Boolean flag = false;
if (!string.IsNullOrEmpty(filter))
{
Setting.Filter sfilter = new Setting.Filter();
sfilter.type = "искать везде";
sfilter.text = filter;
ObservableCollection<Setting.Filter> arr = new ObservableCollection<Setting.Filter>();
arr.Add(sfilter);
if (Utils.AssignedProcedureFromFilter(procedure, arr)) flag = true;
}
else flag = true;
e.Accepted = flag;
}
Video with problem description
Simplified project emitting my functional
On the Russian-speaking forum they explained to me that:
Your case, in fact, is more serious. DataContext you, apparently, the
right one. But your Binding expression is inside the HighlightRules
property setter, which is not part of the visual tree (because it is
not available as a Child element of your control). And elements that
are not inside the visual tree, participate in bindings are only
limited: they do not inherit DataContext, nor access by name through
ElementName. As a solution, bind to an element via x: Reference. In my
(heavily cut) test case, HightlightedText = "{Binding Path =
DataContext.title, Source = {x: Reference MainText}} is triggered."
But, if directly replaced by this, a strange error works: 'Can not
call MarkupExtension. ProvideValue because of a cyclic dependency. The
properties inside the MarkupExtension can not reference objects that
reference the MarkupExtension result.
The workaround for the error was found here: you need to put your element in resources. We get this:
XAML, modified according to the recommendations
<ListBox Name="ProcedureList" ItemsSource="{Binding Path=ProceduresView.View}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Name="ProcedurePanel" PreviewMouseDown="ProcedurePanel_OnPreviewMouseDown">
<DockPanel Width="{c:Binding ElementName=MainPanel, Path=Width-40}">
<!--<TextBlock Name="MainText" TextWrapping="Wrap" FontSize="16" Text="{Binding Path=title}" HorizontalAlignment="Left" />-->
<htb:HighlightTextBlock Name="MainText" TextWrapping="Wrap" FontSize="16"
Text="{Binding Path=title}" HorizontalAlignment="Left">
<htb:HighlightTextBlock.Resources>
<htb:HighlightRule x:Key="HR"
IgnoreCase="{Binding IgnoreCase, Source={StaticResource SourceVm}}"
HightlightedText="{Binding Path=DataContext.title, Source={x:Reference MainText}, Converter={StaticResource getFilter}}">
<htb:HighlightRule.Highlights>
<htb:HighlightBackgroung Brush="Yellow"/>
</htb:HighlightRule.Highlights>
</htb:HighlightRule>
</htb:HighlightTextBlock.Resources>
<htb:HighlightTextBlock.HighlightRules>
<htb:HighlightRulesCollection>
<StaticResource ResourceKey="HR"/>
</htb:HighlightRulesCollection>
</htb:HighlightTextBlock.HighlightRules>
</htb:HighlightTextBlock>
</DockPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I was given advice on the restructuring of XAML, through resources, this partially solved the problem (I successfully got the title text in the converter), but the element ceased to perform its functions (allocation) During the discussion, it was suggested that the component itself should be finalized
#iRumba: In theory, the whole trick should not be necessary if you put
the HighlighRule collection (also) in a visual tree. Then the
DataContext will be automatically inherited and on idea the binding
through ElementName too will work.
#iRumba: I do not remember exactly. It seems, it is necessary to
specify to add all HighlightRule as LogicalChildren (for this purpose
on idea it is necessary to redefine protected internal override
IEnumerator LogicalChildren). This is a complicated, advanced
technique, yes.
Sorry for Google Translator

Found a solution
public class SearchHightlightTextBlock : TextBlock
{
public SearchHightlightTextBlock() : base() { }
public String SearchText
{
get { return (String)GetValue(SearchTextProperty); }
set { SetValue(SearchTextProperty, value); }
}
private static void OnDataChanged(DependencyObject source,
DependencyPropertyChangedEventArgs e)
{
TextBlock tb = (TextBlock)source;
if (tb.Text.Length == 0)
return;
string textUpper = tb.Text.ToUpper();
String toFind = ((String)e.NewValue).ToUpper();
int firstIndex = textUpper.IndexOf(toFind);
String firstStr = "";
String foundStr = "";
if (firstIndex != -1)
{
firstStr = tb.Text.Substring(0, firstIndex);
foundStr = tb.Text.Substring(firstIndex, toFind.Length);
}
String endStr = tb.Text.Substring(firstIndex + toFind.Length,
tb.Text.Length - (firstIndex + toFind.Length));
tb.Inlines.Clear();
tb.FontSize = 16;
var run = new Run();
run.Text = firstStr;
tb.Inlines.Add(run);
run = new Run();
run.Background = Brushes.Yellow;
run.Text = foundStr;
tb.Inlines.Add(run);
run = new Run();
run.Text = endStr;
tb.Inlines.Add(run);
}
public static readonly DependencyProperty SearchTextProperty =
DependencyProperty.Register("SearchText",
typeof(String),
typeof(SearchHightlightTextBlock),
new FrameworkPropertyMetadata(null, OnDataChanged));
}
Use
<parser:SearchHightlightTextBlock SearchText="{Binding Path=title, Converter={StaticResource getFilter}}" Text="{Binding title}"/>

MVVM SelectedValue from ComboBox returns Null

I have a problem. I have a car class with string brand, string model,..
I also have a view with a ComboBox containing Data. When I select an item from the ComboBox "carBrand" or the ComboBox "carModel" and click on a button, I want to create a new car object. But after clicking on the button, the carBrand.SelectedValue.ToString() is delivering a Null value, same for carModel, although I selected an item from the ComboBox.
In my VMClass:
Add a1 = new Add();
c_car m1 = param as c_car;
a1.DataContext = m1;
a1.ShowDialog();
if (a1.DialogResult.HasValue && a1.DialogResult.Value)
{
m1.c_brand = a1.carBrand.SelectedValue.ToString(); //causes NullReferenceException
m1.c_model = a1.carModel.SelectedValue.ToString(); //causes NullReferenceException
m1.c_year = a1.carYear.Content.ToString(); //this works perfectly
m1.c_km = Int32.Parse(a1.carKm.Content.ToString()); //this also works properly
//...
}
Now my View Class:
<!--CarModel ComboBox-->
<ComboBox x:Name="carModel" Style="{StaticResource combobox}" Grid.Column="1"
Margin="20,15,17,14"
ItemsSource="{Binding ModelSelectedBrand}" DisplayMemberPath="c_model" MouseLeave="carModel_MouseLeave"
Grid.Row="2" VerticalAlignment="Center" Height="30" MouseDoubleClick="carModel_MouseDoubleClick">
</ComboBox>
<!--CarYear EditableLabel-->
<Label x:Name="carYear" Content="{Binding ElementName=carModel, Path=SelectedValue.c_year}" Margin="20,14,17,14"
Style="{StaticResource EditableLabelStyle}" Foreground="White"
Grid.Column="1" Grid.Row="5" VerticalAlignment="Center" Height="30">
</Label>
<!--CarKM EditableLabel-->
<Label x:Name="carKm"
Content="{Binding ElementName=carModel, Path=SelectedItem.c_km}" Style="{StaticResource EditableLabelStyle}"
Margin="20,14,17,14"
Grid.Column="1" Grid.Row="3" Foreground="White" VerticalAlignment="Center" Height="30">
</Label>
I hope someone can help me fixing this issue.
Thanks in advance!

So the simple answer (I think, I haven't tested yet) is that there isn't a SelectedValuePath set on your ComboBox (As stated by vesan in the comments).
This means that SelectedValue will always be null.
You could use SelectedItem to return the selected Car and then get the property from that or just set the SelectedValuePath on the ComboBox.
Now, this could of course be made better by using bindings but that is up to you whether you want to implement this.

How to bind an object to a ComboBox, but update a different object when it changes?

I have a Zone object that contains
public int Block {get;set;}
I also have a configuration object which contains minimum and maximum Block values, which are 0 and 2 respectively.
I need to display a ComboBox with the range of valid values, but I need to have the selected value bound to Block.
What's the best way for me to do this?
I've been trying the following:
var blocks = new Dictionary<string, int>();
for (int i = _currentZone.Constraints.Block.Min; i <= _currentZone.Constraints.Block.Max; i++)
{
blocks.Add("Block " + i, i);
}
var blocksCombo = new ComboBoxControl(blocks, GetCurrentBlockValue());
with ComboBoxControl defined as
public ComboBoxControl(Dictionary<string, int> comboItems, int? selectedValue)
{
InitializeComponent();
cboItems.ItemsSource = comboItems;
cboItems.SelectedValue = selectedValue;
}
and the XAML defined as
<Grid>
<ComboBox x:Name="cboItems"
SelectionChanged="combo_SelectionChanged"
Height="25"
SelectedValuePath="Value">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Key}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
</Grid>
When the combo_SelectionChanged event is triggered I manually update the Block value, which isn't ideal.
What I'd like is to be able to set the combo box with the items in the dictionary, but when I change the selected item the value is bound to a different object - the Block. Is this possible?
If so, how can I implement this? If not, is there a better way for me to go about this than what I'm currently doing?

I believe it's as simple as changing you xaml to have...
<ComboBox x:Name="cboItems"
SelectionChanged="combo_SelectionChanged"
Height="25"
SelectedValuePath="Value"
SelectedItem="{Binding Block}">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Key}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
Assuming the data context is setup correctly, you probably need to set the datacontext of the combobox to your Zone object at some point, maybe pass it along with the constructor...
var blocksCombo = new ComboBoxControl(blocks, GetCurrentBlockValue(), this);
public ComboBoxControl(Dictionary<string, int> comboItems, int? selectedValue, Zone zone)
{
InitializeComponent();
cboItems.ItemsSource = comboItems;
cboItems.SelectedValue = selectedValue;
cboItems.DataContext = zone;
}
edit:
Also I think Henk is right, you might want to change the dictionary to instead be a ObservableCollection of Block. (actually just realized block is just an int, this will probably work as a dictionary)

I hope I understood everything right. You have the combobox and want to bind to one specific zone?
<ComboBox ItemsSource="{Binding ValidValuesList}" ItemStringFormat="Block {0}" SelectedItem="{Binding MyZone.Block}"/>
This binds to
public List<int> ValidValuesList
{
get { return new List<int> { 0, 1, 2 }; }
}
and to
public Zone MyZone { get; set; }
in your usercontrols DataContext.

ComboBox SelectedItem binding not updating

I'm a bit puzzled:
this works:
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
<Label Content="Rol" />
<ComboBox ItemTemplate="{StaticResource listRollen}"
Height="23" Width="150"
SelectedItem="{Binding Path=SelectedRol, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
ItemsSource="{Binding Path=allRollen, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
and the property for SelectedRol is:
public TblRollen SelectedRol
{
get { return _selectedRol; }
set
{
if (_selectedRol != value)
{
_selectedRol = value;
OnPropertyChanged("SelectedRol");
}
}
}
But this doesn't work:
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
<Label Content="Soort" />
<ComboBox ItemTemplate="{StaticResource listSoorten}"
Height="23" Width="150"
ItemsSource="{Binding Path=allSoorten}"
SelectedItem="{Binding Path=SelectedProduct, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
</StackPanel>
with following property SelectedProduct:
public TblProduktSoorten SelectedProduct
{
get { return _selectedPSoort; }
set
{
if (_selectedPSoort != value)
{
_selectedPSoort = value;
OnPropertyChanged("SelectedProduct");
}
}
}
somewhere in my code I set SelectedProduct = p.TblProduktSoorten and while debugging, I see the property gets set correctly...

Combobox inside a DataGrid?
If the combobox is in a DataGrid you must add this :
Mode=TwoWay, UpdateSourceTrigger=PropertyChanged
See this : https://stackoverflow.com/a/5669426/16940

Try to use not selected item but value path look at the code sample
<ComboBox Name="projectcomboBox" ItemsSource="{Binding Path=Projects}" IsSynchronizedWithCurrentItem="True" DisplayMemberPath="FullName"
SelectedValuePath="Name" SelectedIndex="0" Grid.Row="1" Visibility="Visible" Canvas.Left="10" Canvas.Top="24" Margin="11,6,13,10">
</ComboBox>
the binding property is
public ObservableCollection<Project> Projects
{
get { return projects; }
set
{
projects = value;
RaisePropertyChanged("Projects");
}
}

This might be related to the fact that apparently attribute order does matter, in your second case the ItemsSource and SelectedItem declarations are swapped.

If you set the SelectedProduct property when SelectedProduct is changed in the property changed event handler, you need to set this property asynchronously.
private void ViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "SelectedProduct")
App.Current.Dispatcher.InvokeAsync(() => SelectedProduct = somevalue);
}

My problem was caused by my own tired brain. Same symptom, maybe it will kick you into seeing your problem.
Setting the SelectedItem must be given an item in the List!! (duhh) Normally this happens naturally but I had a case I got a "Role" from another service (Same object type) and was trying to set it and expecting the combobox to change! ;(
instead of -
Roles = roles;
CurrentRole = role;
remember to do this -
Roles = roles;
CurrentRole = roles.FirstOrDefault(e=> e.ID == role.ID); //(System.Linq)

I don't know if you fixed it yet, but I encountered the same issue today.
It was fixed by making sure the collection for selecteditems was an ObservableCollection.

I think this problem is caused by the type of ItemSource and SelectedItem is mitchmatched.
For example, if the ItemSource is binded to a List of int and the SelectedItem is binded to a string. If you set selected item to null or empty string, the combobox cannot know what item is selected. So the combobox will show nothing.

This might be old but I have not seen the trick that did it for me; I had to add NotifyOnSourceupdate=true to my SelectedItem in the ComboBox

This had me stumped for a while inside a DataGrid, using SelectedItem. Everything was fine but I am deserializing the app state which loads the items and also has a selected item. The collection was there but the selected isn't actually visible until I used the Text="{Binding Path=Score.SelectedResult.Offset}"
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox ToolTip="Score offset results"
ItemsSource="{Binding Score.SearchResults,UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding Score.SelectedResult, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Text="{Binding Path=Score.SelectedResult.Offset}"
SelectedValuePath="Offset"
DisplayMemberPath="Offset"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>