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C# XAML UWP - MenuFlyoutItem List not updating consistently in MenuFlyoutSubItem

this is probably a simple solution - its just a bit long to explain.
I add custom list view items to a ListView at run-time. Each ListView item has a Name, a Bool and a button. The button when clicked displays a Flyout menu which has subitem menu as shown in the image. The subitem menu should only display the name of all other items not itself. The correct behavior is shown in the first image as the "Item 4" menu button was clicked we only see Items 0 to 3 listed in the submenu.
The issue is that if i navigate to a submenu and then later add new items to the listbox, the new items never appear in the submenu for the older items previously navigated to. Like in the image below, where i clicked Item 1 button but only Item 0 and Item 2 are listed and for some reason Items 3 and 4 are not.
Firstly there is a complete minimum VS2019 solution demonstrating the behavior i'm describing above on GitHub here, though i have summarised what i think are the key bits of code below.
Non-boiler plate XAML header (MainPage.Xaml)
xmlns:local="using:DynamicFlyoutMenuTest.ViewModels"
The main ListView defintion and its DataTemplate as well as a button to add ListView items at run-time:
<StackPanel>
<Button Name="AddCustomListItemBtn" Click="AddCustomListItemBtn_Click">Add Custom ListItem</Button>
<ListView
Name="LayerListBox"
Height="Auto"
BorderBrush="{ThemeResource SystemBaseLowColor}"
BorderThickness="1.0"
ItemsSource="{x:Bind ViewModel.MyCustomListItems}">
<ListView.HeaderTemplate>
<DataTemplate>
<Grid Padding="2" Background="{ThemeResource SystemBaseLowColor}">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="190" />
<ColumnDefinition Width="132" />
</Grid.ColumnDefinitions>
<TextBlock Style="{ThemeResource CaptionTextBlockStyle}" Text="Name" />
<TextBlock
Grid.Column="1"
Style="{ThemeResource CaptionTextBlockStyle}"
Text="Active" />
</Grid>
</DataTemplate>
</ListView.HeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate x:Name="TableDataTemplate" x:DataType="local:MyCustomListItem">
<Grid Height="48" AutomationProperties.Name="{x:Bind ItemName}">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="190" />
<ColumnDefinition Width="132" />
<ColumnDefinition Width="132" />
</Grid.ColumnDefinitions>
<TextBlock
Grid.Column="0"
Padding="10"
VerticalAlignment="Center"
Text="{x:Bind ItemName, Mode=OneWay}" />
<CheckBox
Grid.Column="1"
VerticalAlignment="Center"
IsChecked="{x:Bind isEditing, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<Button
Name="exportLayerButton"
Grid.Column="2"
HorizontalAlignment="Stretch"
VerticalAlignment="Center">
<Button.Flyout>
<MenuFlyout Opening="MenuFlyout_Opening">
<MenuFlyoutItem
Name="Action1Btn"
Click="Action1Btn_Click"
Text="Action 1" />
<MenuFlyoutItem
Name="Action2Btn"
Click="Action2Btn_Click"
Text="Action 2" />
<MenuFlyoutSubItem x:Name="SubActionsBtn" Text="Choose Sub Action">
<MenuFlyoutItem Name="NoSubActionBtn" Text="None" />
</MenuFlyoutSubItem>
</MenuFlyout>
</Button.Flyout>
<Polygon
Fill="Black"
Points="0,0 6,4,0,8"
Stroke="Black" />
</Button>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
MainPage.xaml.cs - Add Item to List and Update Flyout Sub Menu Items
private void MenuFlyout_Opening(object sender, object e)
{
//make MenuFlyoutSubItem list all Items in ListView except the one triggering this function
var menuFlyout = sender as MenuFlyout;
// get the menu list we want to add to
MenuFlyoutSubItem menuSubItems = menuFlyout.Items.Where(x => x.Name == "SubActionsBtn").FirstOrDefault() as MenuFlyoutSubItem;
// get the active maplayerlistitem (that triggered this menu opening event)
MyCustomListItem myCustomListItem = (menuFlyout.Target as Button).DataContext as MyCustomListItem;
menuSubItems.Items.Clear();
foreach (var targetItem in ViewModel.MyCustomListItems)
{
if (myCustomListItem.ItemName != targetItem.ItemName)
{
var tItem = new MenuFlyoutItem();
tItem.Text = targetItem.ItemName.ToString();
//tItem.Click += new Windows.UI.Xaml.RoutedEventHandler(DoSomethingBtn_Click);
menuSubItems.Items.Add(tItem);
}
}
}
private void AddCustomListItemBtn_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
{
// Update ListView
var newItem = new MyCustomListItem();
newItem.ItemName = "Item " + ViewModel.MyCustomListItems.Count.ToString();
newItem.isEditing = false;
ViewModel.MyCustomListItems.Add(newItem);
}
MainViewModel.cs
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using Microsoft.Toolkit.Mvvm.ComponentModel;
namespace DynamicFlyoutMenuTest.ViewModels
{
public class MainViewModel : ObservableObject
{
public ObservableCollection<MyCustomListItem> MyCustomListItems = new ObservableCollection<MyCustomListItem>();
public MainViewModel()
{
}
}
public class MyCustomListItem : INotifyPropertyChanged
{
public MyCustomListItem()
{
}
private bool _isEditing;
public bool isEditing
{
get { return _isEditing; }
set
{
_isEditing = value;
NotifyPropertyChanged(this, "isEditing");
}
}
private string _itemName;
public string ItemName
{
get { return _itemName; }
set
{
_itemName = value;
NotifyPropertyChanged(this, "ItemName");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void NotifyPropertyChanged(object sender, string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(sender, e);
}
}
}
}
EDIT
You can view the issue in video at https://www.youtube.com/watch?v=yPNNtsS-n5Q
You can reproduce the issue from the GitHub source by
adding 3 items to the ListView using the "Add..." button.
Navigating to the submenuFlyout of each ListViewItem
Add 2 more Listview Items using the "Add..." button
navigate to the submenuFlyout of the two new items and finally
navigate to submenuFlyout of the original 3 items and see that they haven't updated to reflect the additional ListView items added.

I found a workaround by removing the exsiting MenuFlyoutSubItem and adding a new one each time the Flyout is opened. So it's not ideal, but it does work.
If anyone has as an actual solution, id be happy to mark it as such.
Otherwise here is the workaround:
private void MenuFlyout_Opening(object sender, object e)
{
//make MenuFlyoutSubItem list all Items in ListView except the one triggering this function
var menuFlyout = sender as MenuFlyout;
// get the menu list we want to add to
MenuFlyoutSubItem menuSubItems = menuFlyout.Items.Where(x => x.Name == "SubActionsBtn").FirstOrDefault() as MenuFlyoutSubItem;
// get the active maplayerlistitem (that triggered this menu opening event)
MyCustomListItem myCustomListItem = (menuFlyout.Target as Button).DataContext as MyCustomListItem;
menuFlyout.Items.Remove(menuSubItems);
menuSubItems = new MenuFlyoutSubItem();
menuSubItems.Name = "SubActionsBtn";
menuSubItems.Text = "Choose Sub Action";
foreach (var targetItem in ViewModel.MyCustomListItems)
{
if (myCustomListItem.ItemName != targetItem.ItemName)
{
var tItem = new MenuFlyoutItem();
tItem.Text = targetItem.ItemName.ToString();
//tItem.Click += new Windows.UI.Xaml.RoutedEventHandler(DoSomethingBtn_Click);
menuSubItems.Items.Add(tItem);
}
}
menuFlyout.Items.Add(menuSubItems);
}

Reach a TextBlock from a specific ListViewItem from the ListView in Windows Phone 8.1 XAML programmatically

I am a new developer on Windows Phone 8.1, I am try to reach a specific ListView item from the ListView collection and be able to color it or color the TextBock inside of it, But I can't reach the item or reach any of items inside of ListView, Please take a look for my below code :
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
SQLiteRT db1 = new SQLiteRT();
var db_connection = await db1.Connection("MyDB.sqlite");
List<MyTBL> t_list = db1.GetTable("SELECT * FROM MyTBL LIMIT 4 ORDER BY RANDOM() ;");
db_connection.Close();
LV_Options.ItemsSource = t_list;
}
// my List View called LV_Options
private void LV_Options_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ListView lv1 = sender as ListView;
if (lv1 == null)
return;
MyTBL wrd = lv1.SelectedItem as MyTBL;
if (wrd == null)
return;
TextBlock tb = lv1.FindName("TB_AMean1") as TextBlock;
tb.FontSize = 17; // here I got debug error (it not worked !!!!!!!)
var item = LV_Options.Items.ElementAt(3); // this seems not work also !!!!
item.BackColor = Color.LightSteelBlue;
}
As you can see above, I tried to reach a specific item by LV_Options.Items.ElementAt(3) but it doesn't work! I also tried to reach the TextBlock from the selected List view item, but also not worked !
(Updated)
XAML code :
<!-- Title Panel -->
<StackPanel Grid.Row="0" Margin="19,0,0,0">
<TextBlock Name="TB_Rslt" Text="Here result of your answer" Style="{ThemeResource TitleTextBlockStyle}" Margin="0,12,0,0"/>
<TextBlock Text="page title" Margin="0,-6.5,0,26.5" Style="{ThemeResource HeaderTextBlockStyle}" CharacterSpacing="{ThemeResource PivotHeaderItemCharacterSpacing}"/>
</StackPanel>
<!--TODO: Content should be placed within the following grid-->
<Grid Grid.Row="1" x:Name="ContentRoot" Margin="19,10,19,15">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TextBlock Name="TB_Question" Text="Choose Answer " Margin="0,0,25,0" HorizontalAlignment="Right" FontWeight="Bold" FontSize="22" FontFamily="Verdana" RenderTransformOrigin="0.5,0.5" />
<TextBlock Name="TB_EnWord" Text="" Margin="90,0,15,0" HorizontalAlignment="Left" FontWeight="Bold" FontSize="22" FontFamily="Verdana" RenderTransformOrigin="0.5,0.5" TextAlignment="Right" />
<StackPanel Grid.Row="1" Margin="5,22,0,0">
<ListView Name="LV_Options" SelectionChanged="LV_Options_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Margin="6">
<StackPanel VerticalAlignment="Top" Margin="10,0,0,0">
<TextBlock Name="TB_AMean1" Text="{Binding AMean1}" TextWrapping="Wrap"/>
</StackPanel>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
<Button Name="Btn_Answer" Content="Ansewr" HorizontalAlignment="Left" Grid.Row="1" VerticalAlignment="Bottom" Click="Btn_Answer_Click"/>
My application is a quiz application that offer 4 choices/options as answers for each question, and when user select a true answer, I want to highlight the true answer(true choice) by make its background to green, and if the user selected wrong answer/option I want to make the background of that answer (a specific List View item) with red.
Any help please ?

You're not going to be able to access an element inside a data template like that. Instead, leverage the binding to a view model to set the color and other view-related properties. First, create a wrapper view model for your data class:
public class MyTBLViewModel : INotifyPropertyChanged
{
public MyTBL Entity
{
get { return _entity; }
}
private readonly MyTBL _entity;
public Brush Highlight
{
get { return _brush; }
set
{
_brush = value;
RaisePropertyChanged("Highlight");
}
}
private Brush _highlight;
public double ItemFontSize
{
get { return _itemFontSize; }
set
{
_itemFontSize = value;
RaisePropertyChanged("ItemFontSize");
}
}
private Brush _itemFontSize;
public MyTBLViewModel(MyTBL entity)
{
_entity = entity;
_highlight = new SolidColorBrush(Colors.Transparent);
_itemFontSize = 12;
}
public event PropertyChangedEventArgs PropertyChanged;
protected void RaisePropertyChanged(string propName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propName));
}
}
Use this as your ItemsSource:
List<MyTBLViewModel> t_list = db1.GetTable("SELECT * FROM MyTBL LIMIT 4 ORDER BY RANDOM() ;")
.AsEnumerable().Select(entity => new MyTBLViewModel(entity)).ToList();
Now in your view, bind the view elements to "Highlight" and "ItemFontSize", and to any other properties you like:
<ListView.ItemTemplate>
<DataTemplate>
<Grid Margin="6" Background="{Binding Highlight}">
<StackPanel VerticalAlignment="Top" Margin="10,0,0,0">
<TextBlock Name="TB_AMean1" Text="{Binding Entity.AMean1}" TextWrapping="Wrap"
FontSize="{Binding ItemFontSize}"/>
</StackPanel>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
Finally, you can get the data item from the SelectionChangedEventArgs -- use it to update your view-related properties:
private void LV_Options_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
foreach (var item in e.AddedItems.OfType<MyTBLViewModel>())
{
item.Highlight = new SolidColorBrush(Color.LightSteelBlue);
item.ItemFontSize = 17;
}
foreach (var item in e.RemovedItems.OfType<MyTBLViewModel>())
{
item.Highlight = new SolidColorBrush(Colors.Transparent);
item.ItemFontSize = 12;
}
}

var item = LV_Options.Items.ElementAt(3);
This line is incorrect. It will not return you a TextBlock. I don't know what a .BackColor is, and it should not compile. The Items property in a ListView will return you a list of ListViewItems. If you want to access the inside element from a ListViewItem, you'll need to access the ContentTemplateRoot property.
Do not use var ever. It lets you assume that you know the type, whereas if you explicitly typed the declaration you would realize you're doing it wrong.
MyTBL wrd = lv1.SelectedItem as MyTBL;
if (wrd == null)
return;
TextBlock tb = lv1.FindName("TB_AMean1") as TextBlock;
What is a MyTBL type? FindName is only available to framework DependencyObjects so I'm assuming it's a user control? You have to provide a lot more code to show us what you're doing and what you're setting the ListView's ItemsSource and ItemTemplate with and what these errors are and how you have 2 breaking debug errors at once and what the error messages are.
Comprehending runtime error messages is a huge part of being a good developer.

how to navigate from a listbox in windows phone 7 application

I am building an application for Windows Phone 7 where in a ListBox I am showing data from the web service.
The WebService contains the following data:
News Title, News Description, Date Start and image path.
In the list box I am showing News Title, Date Start and image path.
Now on clicking an item from the list box I want to navigate to another page which should show all the three details along with news description.
My xaml is:
<ListBox Name="listBox1" SelectionChanged="listBox1_SelectionChanged">
<!-- SelectionChanged="listBox1_SelectionChanged"-->
<ListBox.ItemTemplate>
<DataTemplate>
<Button>
<Button.Content>
<ScrollViewer HorizontalScrollBarVisibility="Auto" Height="80" Width="400">
<StackPanel Orientation="Horizontal" Margin="0,0,0,0">
<Image Source="{Binding ImageBind }" Height="80" Width="120"/>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding Path=News_Title}" TextWrapping="Wrap"></TextBlock>
<!-- <TextBlock Text="{Binding Path=News_Description}" TextWrapping="Wrap"></TextBlock>-->
<TextBlock Text="{Binding Path=Date_Start}" TextWrapping="Wrap" ></TextBlock>
</StackPanel>
</StackPanel>
</ScrollViewer>
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The .cs file is:
public News()
{
InitializeComponent();
KejriwalService.aapSoapClient client = new KejriwalService.aapSoapClient();
client.getarvindNewsCompleted += new EventHandler<KejriwalService.getarvindNewsCompletedEventArgs>(client_getarvindNewsCompleted);
client.getarvindNewsAsync();
progressName.Visibility = System.Windows.Visibility.Visible;
}
void client_getarvindNewsCompleted(object sender, KejriwalService.getarvindNewsCompletedEventArgs e)
{
string result = e.Result.ToString();
List<Newss> listData = new List<Newss>();
XDocument doc = XDocument.Parse(result);
progressName.Visibility = System.Windows.Visibility.Collapsed;
foreach (var location in doc.Descendants("UserDetails"))
{
Newss data = new Newss();
data.News_Title = location.Element("News_Title").Value;
//data.News_Description = location.Element("News_Description").Value;
data.Date_Start = location.Element("Date_Start").Value;
data.image_path = location.Element("image_path").Value;
data.ImageBind = new BitmapImage(new Uri( #"http://political-leader.vzons.com/ArvindKejriwal/images/uploaded/"+data.image_path, UriKind.Absolute));
listData.Add(data);
}
listBox1.ItemsSource = listData;
}
Now in a new page say newsdetails.xaml i want to navigate from this page and show the complete details.
Please help.
I am stuck in this as I am new in this domain.
I am almost done with my app if this is done.
private void listBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (listBox1.SelectedIndex == -1)
return;
var item = listBox1.SelectedItem as Newss;
if (!IsolatedStorageSettings.ApplicationSettings.Contains("SelectedObject"))
{
IsolatedStorageSettings.ApplicationSettings["SelectedObject"] = item;
NavigationService.Navigate(new Uri("/NewsDetails.xaml", UriKind.Relative));
}
}

Define static global variables in that page where your listbox selection change event is:
public static string title;
public static string news_description;
On listbox selection change assign these variables:
private void listBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (listBox1.SelectedIndex == -1)
return;
var item = listBox1.SelectedItem as Newss;
if (!IsolatedStorageSettings.ApplicationSettings.Contains("SelectedObject"))
{
IsolatedStorageSettings.ApplicationSettings["SelectedObject"] = item;
title=item.News_Title;
news_description=item.News_Description;
NavigationService.Navigate(new Uri("/NewsDetails.xaml", UriKind.Relative));
}
}
And in your navigation NewsDetails.cs page Access these items like this:
string Title=YourPageName.title;//
string Description=YourPageName.news_description;
show these values as you want

WP7 ListBox selected item is not changing the color

I have a ListBox in app, it has an image and textbox inside. I want to set 2 colors and 3rd one for selected item.
<ListBox.ItemTemplate>
<DataTemplate x:Name="Template1">
<StackPanel Orientation="Horizontal" >
<Image Width="100" Height="100" Source="{Binding SmallImage}"></Image>
<Grid>
<TextBlock Text="{Binding Caption}" Foreground="{Binding txtColor}"></TextBlock>
</Grid>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
when I'm changing the foreground color, then the selected item doesn't highlights (I kept it by default).
I tried to add an event to ListBox,
private void DList_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ListBoxItem selectedItem = DList.SelectedItem as ListBoxItem;
selectedItem.Foreground = new SolidColorBrush(Colors.Red);
}
but it shows an exception:
NullReferenceException
"Use the "new" keyword to create an object instance"

If you're going to handle the SelectionChanged event, then you might as well use the SelectionChangedEventArgs object:
private void DList_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
var selectedDataObject = e.AddedItems[0]; // assuming single selection
ListBoxItem selectedItem =
ListBoxName.ItemContainerGenerator.ContainerFromItem(selectedDataObject);
selectedItem.Foreground = new SolidColorBrush(Colors.Red);
}

Win8 ListView Tap does not select item

Hi so I'm doing a note taking app and Ive got it connected to my SQL Azure Database.
The items get automatically populated through MobileServiceCollectionView.
After tapping an item, a detailView should be opened to the right...
I dont know why but tapping an item does not select it, so I cant check for listView.SelectedItem in the noteListView_Tapped event.....
What is wrong with my listview?
<ListView x:Name="noteListView" Margin="20,0,0,0" Tapped="noteListView_Tapped">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="2">
<CheckBox x:Name="CheckBoxComplete" IsChecked="{Binding Complete, Mode=TwoWay}" Checked="CheckBoxComplete_Checked" Padding="3"/>
<TextBlock x:Name="TextBlockTodoItem" Text="{Binding Title}" Padding="3" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
And here the Tapped event.. It crashed on TodoItem t = (TodoItem)lv.SelectedItem;
So i added the if condition and now nothing happens except for the debug prints.
private void noteListView_Tapped(object sender, TappedRoutedEventArgs e)
{
Debug.WriteLine("0");
ListView lv = (ListView)sender;
if (lv.Items.Count > 0)
{
if (lv.SelectedItems.Count > 0)
{
TodoItem t = (TodoItem)lv.SelectedItem;
Debug.WriteLine("1");
Debug.WriteLine(t.Title);
try
{
Location l = TodoItem.StringToLocation(t.LocationTaken);
Debug.WriteLine("2");
MapLayer.SetPosition(locationIcon, l);
map.SetView(l, 15.0f);
}
catch (Exception ex)
{
Debug.WriteLine("Map set position failed.: " + ex.Message);
}
}
}
}
So what do I have to change or how do I know which item has been clicked/selected?

Why not just use the SelectionChanged event on the listview?
<ListView SelectionChanged="noteListView_SelectionChanged">
Then in your code behind
private void noteListView_SelectionChanged(object sender, RoutedEventArgs e)
{
if((sender as ListView).Items.Count > 0)
{
.....
}
}
I think (though I'm not sure) that your problem is that tapping the listView, and so the tapped event, is not the same as selecting an item in the list.