First time using a ListBox and after following this , I'm having issues having data actually display. The ListBox is just empty and white with no text in it.
I made a separate textbox to test an individual "Tweet" object out and it is indeed outputting what I want it to. I think my issue either lies in XAML or Tweets. But nothing looks out of place.
Tracing reveals that Tweets successfully adds a proper Tweet object with what I need. But my ListBox Count is always 0.
<Grid Opacity="0.8">
<Grid.Resources>
<local:Tweets x:Key="tweets"/>
</Grid.Resources>
<Rectangle Fill="Gray" Margin="1523,0,0,729" Height="321" Width="389">
<Rectangle.Effect>
<DropShadowEffect/>
</Rectangle.Effect></Rectangle>
<ListBox ItemsSource="{StaticResource tweets}" Height="321" Margin="340,40,1096,0" x:Name="twitterBox" VerticalAlignment="Top" Width="476">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Height="132">
<!--<Image Source="{Binding imgSrc}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>-->
<StackPanel Width="370">
<TextBlock Text="{Binding user}" FontSize="28" />
<TextBlock Text="{Binding tweet}" TextWrapping="Wrap" FontSize="24" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
In my cs:
public class Tweet
{
public String imgSrc { get; set; }
public String user { get; set; }
public String tweet { get; set; }
public Tweet(String user, String tweet, String img)
{
this.imgSrc = img;
this.user = user;
this.tweet = tweet;
}
}
public class Tweets : ObservableCollection<Tweet>
{
public Tweets()
{
}
public void addTweet(Tweet tweet)
{
Add(tweet);
}
}
public void SomeFunction()
{
Tweets myTwitter = new Tweets();
myTwitter.addTweet(new Tweet(tweet.User.ScreenName, tweet.Text, tweet.User.ProfileImageUrl));
}
ItemTemplate code is ok but you should remove this Margin="1523,0,0,729".
ListBox is empty because items source is empty. You should add some items.
To add items in XAML you should add default constructor to Tweet class.
public class Tweet
{
public String imgSrc { get; set; }
public String user { get; set; }
public String tweet { get; set; }
public Tweet(){}
public Tweet(String user, String tweet, String img)
{
this.imgSrc = img;
this.user = user;
this.tweet = tweet;
}
}
And now you can write something like this:
...
<Grid.Resources>
<local:Tweets x:Key="tweets">
<local:Tweet imgSrc="imgSrc1" user="user1" tweet="tweet1" />
<local:Tweet imgSrc="imgSrc2" user="user2" tweet="tweet2" />
</local:Tweets>
</Grid.Resources>
...
Result:
Add items in code-behind.
To do that you should use function: FindResource (msdn).
XAML:
<Grid Name="mainGrid" Opacity="0.8">
<Grid.RowDefinitions>
<RowDefinition Height="30" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid.Resources>
<local:Tweets x:Key="tweets">
<local:Tweet imgSrc="imgSrc1" user="user1" tweet="tweet1" />
<local:Tweet imgSrc="imgSrc2" user="user2" tweet="tweet2" />
</local:Tweets>
</Grid.Resources>
<Button Content="Add new item" Click="Button_Click" />
<ListBox x:Name="twitterBox" ItemsSource="{StaticResource tweets}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
Grid.Row="1">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Height="132">
<!--<Image Source="{Binding imgSrc}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>-->
<StackPanel Width="370">
<TextBlock Text="{Binding user}" FontSize="28" />
<TextBlock Text="{Binding tweet}" TextWrapping="Wrap" FontSize="24" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
Code-behind:
private void Button_Click(object sender, RoutedEventArgs e)
{
var coll = mainGrid.FindResource("tweets") as Tweets;
if (coll != null)
{
coll.Add(new Tweet("user", "name", "url"));
}
}
Second solution:
The better solution will be if you will create an instance of class Tweets in code behind.
XAML:
<Grid Name="mainGrid" Opacity="0.8">
<Grid.RowDefinitions>
<RowDefinition Height="30" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Button Content="Add new item" Click="Button_Click" />
<ListBox x:Name="twitterBox" ItemsSource="{Binding tweets}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
Grid.Row="1">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Height="132">
<!--<Image Source="{Binding imgSrc}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>-->
<StackPanel Width="370">
<TextBlock Text="{Binding user}" FontSize="28" />
<TextBlock Text="{Binding tweet}" TextWrapping="Wrap" FontSize="24" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
Code-behind:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
tweets = new Tweets();
tweets.Add(new Tweet("user1", "name1", "url1"));
tweets.Add(new Tweet("user2", "name2", "url2"));
tweets.Add(new Tweet("user3", "name3", "url3"));
this.DataContext = this;
}
public Tweets tweets { get; set; }
private void Button_Click(object sender, RoutedEventArgs e)
{
tweets.Add(new Tweet("user4", "name4", "url4"));
}
}
You add tweets to a different collection than the one displayed by the listbox.
Related
I need to change the color of a rectangle in a GridView when the item is selected.
Unselected item
Selected item
My Main Page in XAML.
<Page
x:Class="GridViewWithSelectedItem.Views.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:views="using:GridViewWithSelectedItem.Views"
Style="{StaticResource PageStyle}"
mc:Ignorable="d">
<Page.Resources>
<DataTemplate x:Key="TileTemplate" x:DataType="views:Article">
<Border BorderThickness="2,2,2,2" BorderBrush="#FF868484" Margin="3,3,3,3" HorizontalAlignment="Stretch" MaxWidth="600" MinWidth="525">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="10"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="60"/>
<RowDefinition/>
</Grid.RowDefinitions>
<Rectangle Fill="Black" Grid.RowSpan="3"/>
<StackPanel Orientation="Horizontal" Grid.Row="0" Grid.Column="1">
<TextBlock FontSize="20" Margin="0,0,5,0" TextWrapping="Wrap" Foreground="DarkBlue" FontWeight="Bold" Text="{x:Bind Number}"/>
<TextBlock FontSize="20" TextWrapping="Wrap" Foreground="DarkBlue" Text="{x:Bind Title}" FontWeight="Bold"/>
</StackPanel>
<TextBlock Grid.Row="1" Grid.Column="1" FontSize="20" Text="{x:Bind Description}" TextWrapping="WrapWholeWords"/>
<StackPanel Background="LightBlue" Padding="5,0,0,0" Grid.Row="2" Grid.Column="1">
<StackPanel Orientation="Horizontal">
<TextBlock FontSize="20" Margin="0,0,5,0" TextWrapping="Wrap">Date :</TextBlock>
<TextBlock Foreground="Red" FontSize="20" TextWrapping="Wrap" Text="{x:Bind Date}" FontWeight="Bold"/>
</StackPanel>
</StackPanel>
</Grid>
</Border>
</DataTemplate>
</Page.Resources>
<Grid x:Name="ContentArea" Margin="{StaticResource MediumLeftRightMargin}">
<Grid Background="White" VerticalAlignment="Top" HorizontalAlignment="Stretch" Margin="0,25,0,0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="600"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="60"/>
<RowDefinition Height="800"/>
</Grid.RowDefinitions>
<TextBlock Text="The Guardian" FontSize="35" FontWeight="Bold" Grid.ColumnSpan="2" HorizontalAlignment="Center"/>
<GridView
BorderThickness="2,2,0,2" BorderBrush="#FF868484"
MinWidth="600"
Grid.Column="0"
Grid.Row="1"
Padding="5,5,5,5"
HorizontalAlignment="Center"
CanDragItems="False"
IsItemClickEnabled="true"
IsTapEnabled="False"
IsSwipeEnabled="False"
ItemsSource="{x:Bind Articles}"
ItemTemplate="{StaticResource TileTemplate}"
SelectedItem="{x:Bind Mode=TwoWay, Path=SelectedArticle}"
/>
<RelativePanel Grid.Row="1" Grid.Column="1" Background="WhiteSmoke" BorderThickness="2" BorderBrush="#FF868484" Padding="10">
<Grid RelativePanel.AlignLeftWithPanel="True" RelativePanel.AlignRightWithPanel="True">
<Grid VerticalAlignment="Top">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<StackPanel Orientation="Horizontal" Grid.Row="0">
<TextBlock FontSize="20" Margin="0,0,5,0" TextWrapping="Wrap" Foreground="DarkBlue" FontWeight="Bold" Text="{x:Bind Path=SelectedArticle.Number, Mode=OneWay}"/>
<TextBlock FontSize="20" TextWrapping="Wrap" Foreground="DarkBlue" Text="{x:Bind Path=SelectedArticle.Title, Mode=OneWay}" FontWeight="Bold"/>
</StackPanel>
<TextBlock Grid.Row="1" FontSize="20" Text="{x:Bind Path=SelectedArticle.Description, Mode=OneWay}" TextWrapping="WrapWholeWords"/>
</Grid>
</Grid>
<RelativePanel Background="LightBlue" Padding="5,0,0,0" RelativePanel.AlignBottomWithPanel="True" RelativePanel.AlignLeftWithPanel="True" RelativePanel.AlignRightWithPanel="True">
<StackPanel Orientation="Horizontal">
<TextBlock FontSize="20" Margin="0,0,5,0" TextWrapping="Wrap">Date :</TextBlock>
<TextBlock Foreground="Red" FontSize="20" TextWrapping="Wrap" Text="{x:Bind Path=SelectedArticle.Date, Mode=OneWay}" FontWeight="Bold"/>
</StackPanel>
</RelativePanel>
</RelativePanel>
</Grid>
</Grid>
</Page>
And the class of my XAML Page.
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using Windows.UI.Xaml.Controls;
namespace GridViewWithSelectedItem.Views
{
public sealed partial class MainPage : Page, INotifyPropertyChanged
{
public ObservableCollection<Article> Articles;
private Article _selectedArticle;
public Article SelectedArticle
{
get { return _selectedArticle; }
set { Set(ref _selectedArticle, value); }
}
public MainPage()
{
InitializeComponent();
Articles = new ObservableCollection<Article>();
Articles.Add(new Article(0, "Uighurs", "Being young' leads to detention in China's Xinjiang region", DateTime.Parse("09/12/2020")));
Articles.Add(new Article(1, "Brexit", "Chances of Brexit deal hang on Boris Johnson and Ursula von der Leyen dinner", DateTime.Parse("09/12/2020")));
Articles.Add(new Article(2, "Environment", "Secretive ‘gold rush’ for deep-sea mining dominated by handful of firms", DateTime.Parse("09/12/2020")));
Articles.Add(new Article(3, "Juukan Gerge induiry", "Juukan Gorge inquiry: Rio Tinto's decision to blow up Indigenous rock shelters 'inexcusable'", DateTime.Parse("09/12/2020")));
Articles.Add(new Article(4, "Australia", "British journalist uncovered Australian woman's alleged plan to kill parents on dark web, police say", DateTime.Parse("09/12/2020")));
Articles.Add(new Article(5, "Coronavirus", "Nine out of 10 in poor nations to miss out on inoculation as west buys up Covid vaccines", DateTime.Parse("09/12/2020")));
}
public event PropertyChangedEventHandler PropertyChanged;
private void Set<T>(ref T storage, T value, [CallerMemberName]string propertyName = null)
{
if (Equals(storage, value))
{
return;
}
storage = value;
OnPropertyChanged(propertyName);
}
private void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public class Article
{
public int Number { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public DateTime Date { get; set; }
public Article(int number, string title, string description, DateTime date)
{
Number = number;
Title = title;
Description = description;
Date = Date;
}
}
}
I see AutomationProperty.name can help me but i don't understand how to use it.
I found a way to change the color of a selected item in my class but i need to recreate the collection and i cost lot of resources. I think its possible to make it in XAML code.
Edit: I made a simple exemple of my code.
OneDrive link
You could add a Brush property into the Article class, and bind the Brush property to Rectangle.Fill property of your DataTemplate to change the color when an item of GridView control is selected.
Please check the following code:
In DataTemplate of your xaml file:
<Rectangle x:Name="rectangle" Fill="{x:Bind Brush}" Grid.RowSpan="3"/>
……
<GridView …… SelectionChanged="GridView_SelectionChanged" />
In code-behind:
public class Article
{
……
public SolidColorBrush Brush { get; set; }
public Article(int number, string title, string description, DateTime date)
{
……
Brush = new SolidColorBrush(Colors.Black);
}
}
Add a _preSelectedArticle property to save the previous item in MainPage class:
private Article _preSelectedArticle;
Change the value of Brush property of selected item and previous selected item:
private void GridView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if(_preSelectedArticle==null)
{
SelectedArticle.Brush.Color = Colors.Green;
_preSelectedArticle = SelectedArticle;
}
if (_preSelectedArticle!=null&&_preSelectedArticle!= SelectedArticle)
{
_preSelectedArticle.Brush.Color = Colors.Black;
SelectedArticle.Brush.Color = Colors.Green;
_preSelectedArticle = SelectedArticle;
}
}
I am trying to make a button in a viewmodel recognize that a radio button in another view model (a UserControl that is activated on the first viewmodel) has been selected, thus enabling the button in the first viewmodel.
I have a UserControl AlbumsDisplayViewModel within my base view model BaseViewModel.
In BaseView XAML There's a button (OpenAlbum) which is supposed to be enabled when a radio button on the AlbumsDisplayView is selected (see CanOpenAlbum).
BaseView XAML:
<Canvas x:Name="cnvsInputWrapper" Background="LightGray"
Grid.Column="4" Grid.Row="1" Grid.RowSpan="4"
Margin="5">
<Canvas.OpacityMask>
<VisualBrush Visual="{Binding ElementName=maskRoundEdges}" />
</Canvas.OpacityMask>
<DockPanel Margin="15, 25">
<ContentControl x:Name="ActiveItem" />
</DockPanel>
</Canvas>
<!-- Action Buttons section -->
<Grid Grid.Row="3" Grid.Column="1" Grid.RowSpan="2">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="12" />
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="12" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="12" />
<RowDefinition Height="auto" />
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
<RowDefinition Height="12" />
</Grid.RowDefinitions>
<Button Grid.Row="1" Grid.Column="1" x:Name="OpenAlbum"
IsEnabled="{Binding CanOpenAlbum}">
<StackPanel Orientation="Vertical">
<TextBlock>Open</TextBlock>
<TextBlock>Album</TextBlock>
</StackPanel>
</Button>
</Grid>
BaseViewModel C#:
public class BaseViewModel : Conductor<object>
{
private AlbumsDisplayViewModel m_vmAlbumsDisplay; // Initialized in another function.
public BaseViewModel()
{
}
public bool CanOpenAlbum() => (m_vmAlbumsDisplay != null) && (m_vmAlbumsDisplay.GetSelectedAlbum() != null);
public void OpenAlbum()
{
AlbumModel album = m_vmAlbumsDisplay.GetSelectedAlbum();
//ActivateItem(/*albumViewModel(album)*/);
}
}
AlbumsDisplayView XAML:
<ItemsControl x:Name="Albums" FlowDirection="LeftToRight"
Margin="10, 0">
<ItemsControl.ItemTemplate>
<DataTemplate DataType="{x:Type vms:AlbumViewModel}">
<StackPanel Orientation="Horizontal" Margin="0, 5">
<RadioButton GroupName="rdbtnAlbums"
IsChecked="{Binding IsSelected}" />
<!-- Album Details -->
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
AlbumsDisplayViewModel C#:
class AlbumsDisplayViewModel : Screen
{
private ObservableCollection<AlbumViewModel> m_albums;
public AlbumsDisplayViewModel()
{
}
public ObservableCollection<AlbumViewModel> Albums
{
get { return m_albums; }
set
{
m_albums = value;
NotifyOfPropertyChange(() => Albums);
}
}
public AlbumModel GetSelectedAlbum()
{
AlbumModel res = null;
foreach (var vmAlbum in Albums)
{
if (vmAlbum.IsSelected)
{
res = vmAlbum.Album;
break;
}
}
return res;
}
}
And last, AlbumViewModel C#:
class AlbumViewModel : Screen
{
private AlbumModel m_albumModel;
private bool m_isSelected;
public AlbumViewModel(AlbumModel albumModel)
{
m_albumModel = albumModel;
}
public AlbumModel Album
{
get { return m_albumModel; }
set
{
m_albumModel = value;
NotifyOfPropertyChange(() => Album);
}
}
public bool IsSelected
{
get { return m_isSelected; }
set
{
m_isSelected = value;
NotifyOfPropertyChange(() => IsSelected);
}
}
}
I expected that when IsSelected in AlbumViewModel is changed (when the user selects a radio button), the OpenAlbum button will be enabled, because CanOpenAlbum will return true, but I have realized that CanOpenAlbum wasn't even called for some reason. What do I need to do so CanOpenAlbum will be notified to be called whenever a radio button is selected?
After searching for an answer for a long time, I decided that it will be better to search for a better solution, instead of an answer. I've discovered that a ListBox element has a SelectedItem property, which eliminates the need for radio buttons.
Eventually, I replaced the ItemsControl with a ListBox, and I;m happy with the results.
AlbumDisplayView XAML (only this has changed):
<ScrollViewer x:Name="Scroller" Height="300"
FlowDirection="RightToLeft">
<ListBox x:Name="Albums" FlowDirection="LeftToRight"
Background="Transparent" Margin="10, 0"
BorderThickness="0" SelectedItem="{Binding SelectedAlbum}">
<ItemsControl.ItemTemplate>
<DataTemplate DataType="{x:Type vms:AlbumViewModel}">
<StackPanel Orientation="Horizontal" Margin="0, 5">
<!-- Album Details -->
<StackPanel Orientation="Vertical">
<StackPanel Grid.Row="1" Grid.Column="1"
Orientation="Horizontal" Margin="12, 0">
<TextBlock Text="{Binding Album.Name}" />
<TextBlock Text=" - User#" />
<TextBlock Text="{Binding Album.OwnerID}" />
</StackPanel>
<TextBlock Text="{Binding Album.CreationDate}"
FontSize="12" Margin="12, 0" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ListBox>
</ScrollViewer>
I have a list on page one with car objects. I want to click on a car from the list and click a button which will send the selected car to a list on another uwp page.
I am trying to put the listCar.selecteditems in an empty list I created called purchase and display purchase on page 2. With the code I have at the moment, it is only displaying ProjectName_Car in the list on page 2.
Any help on displaying this properly is appreciated.
Page1.xaml.cs
private void Add_Click(object sender, RoutedEventArgs e)
{
var query = listCars.SelectedItems.ToList().Cast<Car>();
foreach (var item in query)
{
purchase.Add(item);
}
liistCar.ItemsSource = purchase;
Frame.Navigate(typeof(Page2), listCar.Items);
}
Page2.xaml.cs
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
lstCars.ItemsSource = e.Parameter as List<Car> ;
}
Edit: Page1.xaml
<ListBox Name="listCars" ItemsSource="{x:Bind cars}" >
<ListBox.ItemTemplate>
<DataTemplate x:DataType="Car">
<StackPanel Padding="20">
<Image Width="200" Height="150" HorizontalAlignment="Left" Source="{x:Bind imgCar}" />
<TextBlock FontSize="22" HorizontalAlignment="Left" Text="{x:Bind Name}" Style="{StaticResource HeaderTextBlockStyle}"/>
<TextBlock FontSize="16" HorizontalAlignment="Left"> € <Run Text="{Binding Price}" /></TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
This one transfers your selected car list object to next page as parameter with all its properties.
MainPage.xaml
<Page
x:Class="App1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App1"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Name="YourPage"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<StackPanel x:Name="Stacky" HorizontalAlignment="Stretch" Background="Aqua" VerticalAlignment="Stretch">
<ListBox Name="listCars" ItemsSource="{x:Bind cars}" SelectionMode="Multiple" Grid.Column="0" Grid.Row="1" Background="#FFF1EFEF" Opacity="0.7" Foreground="Black" Margin="10,10,94,10" Grid.RowSpan="2">
<ListBox.ItemTemplate>
<DataTemplate x:DataType="local:Car">
<StackPanel Padding="20" BorderThickness="2" BorderBrush="Black">
<Image Width="200" Height="150" HorizontalAlignment="Left" Source="{x:Bind imgCar}" />
<TextBlock FontSize="22" HorizontalAlignment="Left" Text="{x:Bind name}" Style="{StaticResource HeaderTextBlockStyle}"/>
<TextBlock FontSize="16" HorizontalAlignment="Left"> € <Run Text="{x:Bind price}" /></TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Button Content="Done Selecting" Click="Add_Click"></Button>
</StackPanel>
</Page>
MainPage.xaml.cs
public sealed partial class MainPage : Page
{
List<Car> cars = new List<Car>();
public MainPage()
{
cars.Add(new Car() { imgCar = "ms-appx:///Assets/1.jpg", name = "Car1", price = "10000" });
cars.Add(new Car() { imgCar = "ms-appx:///Assets/2.jpg", name = "Car2", price = "10001" });
cars.Add(new Car() { imgCar = "ms-appx:///Assets/3.jpg", name = "Car3", price = "10002" });
this.InitializeComponent();
}
private void Add_Click(object sender, RoutedEventArgs e)
{
List<Car> mySelectedItems = new List<Car>();
foreach (Car item in listCars.SelectedItems)
{
mySelectedItems.Add(item);
}
Frame.Navigate(typeof(Page2), mySelectedItems);
}
}
public class Car
{
public string imgCar { get; set; }
public string name { get; set; }
public string price { get; set; }
}
Page2.xaml
<Page
x:Class="App1.Page2"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App1"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<ListBox Name="listCars" SelectionMode="Multiple" Grid.Column="0" Grid.Row="1" Background="#FFF1EFEF" Opacity="0.7" Foreground="Black" Margin="10,10,94,10" Grid.RowSpan="2">
<ListBox.ItemTemplate>
<DataTemplate x:DataType="local:Car">
<StackPanel Padding="20" BorderThickness="2" BorderBrush="Black">
<Image Width="200" Height="150" HorizontalAlignment="Left" Source="{x:Bind imgCar}" />
<TextBlock FontSize="22" HorizontalAlignment="Left" Text="{x:Bind name}" Style="{StaticResource HeaderTextBlockStyle}"/>
<TextBlock FontSize="16" HorizontalAlignment="Left"> € <Run Text="{x:Bind price}" /></TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Page>
Page2.xaml.cs
public sealed partial class Page2 : Page
{
public Page2()
{
this.InitializeComponent();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
var items = e.Parameter as List<Car>;
listCars.ItemsSource = items;
base.OnNavigatedTo(e);
}
}
I am trying to build a diary app that uses hub as user interface and update the UI after saving the diary. I already implemented the INotifyPropertyChanged but it didn't work. I want the item that is added after saving to appear on the hub immediately.
public class SampleDataGroup : INotifyPropertyChanged
{
public SampleDataGroup()
{
UniqueId = string.Empty;
Title = string.Empty;
Subtitle = string.Empty;
Description = string.Empty;
ImagePath = string.Empty;
Items = new ObservableCollection<DiaryData>();
}
public string UniqueId { get; private set; }
public string Title { get; private set; }
public string Subtitle { get; private set; }
public string Description { get; private set; }
public string ImagePath { get; private set; }
private ObservableCollection<DiaryData> _items;
public ObservableCollection<DiaryData> Items { get{return _items;} private set
{
OnPropertyChanged("Items");
_items = value;
} }
public override string ToString()
{
if (this.Title != null)
{
return this.Title;
}
else
{
System.Diagnostics.Debug.WriteLine("this is null at tostring");
return null;
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
}
public sealed class SampleDataSource : INotifyPropertyChanged
{
private static SampleDataSource _sampleDataSource = new SampleDataSource();
private ObservableCollection<SampleDataGroup> _groups = new ObservableCollection<SampleDataGroup>();
public ObservableCollection<SampleDataGroup> Groups
{
get { return this._groups; }
set { }
}
public static async Task<IEnumerable<SampleDataGroup>> GetGroupsAsync()
{
await _sampleDataSource.GetSampleDataAsync();
return _sampleDataSource.Groups;
}
public static async Task<SampleDataGroup> GetGroupAsync(string uniqueId)
{
System.Diagnostics.Debug.WriteLine("GetGroupAsync is entered phase 1");
await _sampleDataSource.GetSampleDataAsync();
// Simple linear search is acceptable for small data sets
System.Diagnostics.Debug.WriteLine("GetGroupAsync is entered phase 2");
var matches = _sampleDataSource.Groups.Where((group) => group.UniqueId.Equals(uniqueId));
if (matches.Count() == 1) return matches.First();
return null;
}
public static async Task<DiaryData> GetItemAsync(string uniqueId)
{
await _sampleDataSource.GetSampleDataAsync();
System.Diagnostics.Debug.WriteLine("GetItemAsync is entered");
// Simple linear search is acceptable for small data sets
var matches = _sampleDataSource.Groups.SelectMany(group => group.Items).Where((item) => item.UniqueId.Equals(uniqueId));
if (matches.Count() == 1) return matches.First();
else return null;
}
private async Task GetSampleDataAsync()
{
System.Diagnostics.Debug.WriteLine("GetSampleDataAsync is entered");
//if (this._groups.Count != 0)return;
Uri dataUri = new Uri("ms-appdata:///local/data.json");
StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(dataUri);
string jsonText = await FileIO.ReadTextAsync(file);
JsonArray jsonArray = JsonArray.Parse(jsonText);
SampleDataGroup group = new SampleDataGroup();
foreach (JsonValue itemValue in jsonArray)
{
JsonObject itemObject = itemValue.GetObject();
group.Items.Add(new DiaryData(itemObject["Title"].GetString(),
itemObject["Content"].GetString(),
itemObject["Coordinate"].GetString(),
itemObject["UniqueId"].GetString(),
itemObject["ImagePath"].GetString(),
itemObject["VideoPath"].GetString()));
System.Diagnostics.Debug.WriteLine(itemObject["Title"].GetString());
}
this.Groups.Add(group);
System.Diagnostics.Debug.WriteLine("GetSampleDataAsync is finished");
}
//}
public event PropertyChangedEventHandler PropertyChanged;
}
here's my XAML File
<Page
x:Class="DiaryAppHub.HubPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:DiaryAppHub"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:data="using:DiaryAppHub.Data"
DataContext="{Binding DefaultViewModel, RelativeSource={RelativeSource Self}}"
d:DataContext="{Binding Source={d:DesignData Source=/DataModel/SampleData.json, Type=data:data.json}}"
mc:Ignorable="d">
<Page.Resources>
<DataTemplate x:Key="HubSectionHeaderTemplate">
<TextBlock Margin="0,0,0,-9.5" Text="{Binding}"/>
</DataTemplate>
<!-- Grid-appropriate item template as seen in section 2 -->
<DataTemplate x:Key="Standard200x180TileItemTemplate">
<Grid Margin="0,0,9.5,9.5" Background="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}">
<Image Source="{Binding ImagePath}" Stretch="UniformToFill" AutomationProperties.Name="{Binding Title}" Height="138.5" Width="138.5"/>
<TextBlock Text="{Binding Title}" VerticalAlignment="Bottom" Margin="9.5,0,0,6.5" Style="{ThemeResource BaseTextBlockStyle}"/>
</Grid>
</DataTemplate>
<DataTemplate x:Key="StandardTripleLineItemTemplate">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Border Background="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}" Margin="0,9.5,0,0" Grid.Column="0" HorizontalAlignment="Left">
<Image Source="{Binding ImagePath}" Stretch="UniformToFill" AutomationProperties.Name="{Binding Title}" Height="79" Width="79"/>
</Border>
<StackPanel Grid.Column="1" Margin="14.5,0,0,0">
<TextBlock Text="{Binding Title}" Style="{ThemeResource ListViewItemTextBlockStyle}"/>
<TextBlock Text="{Binding Description}" Style="{ThemeResource ListViewItemContentTextBlockStyle}" Foreground="{ThemeResource PhoneMidBrush}" />
<TextBlock Text="{Binding Subtitle}" Style="{ThemeResource ListViewItemSubheaderTextBlockStyle}" />
</StackPanel>
</Grid>
</DataTemplate>
<DataTemplate x:Key="StandardDoubleLineItemTemplate">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Border Background="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}" Margin="0,9.5,0,0" Grid.Column="0" HorizontalAlignment="Left">
<Image Source="{Binding ImagePath}" Stretch="UniformToFill" AutomationProperties.Name="{Binding Title}" Height="79" Width="79"/>
</Border>
<StackPanel Grid.Column="1" Margin="14.5,0,0,0">
<TextBlock Text="{Binding Title}" Style="{ThemeResource ListViewItemTextBlockStyle}" Foreground="Black"/>
<TextBlock Text="{Binding Subtitle}" Style="{ThemeResource ListViewItemSubheaderTextBlockStyle}" Foreground="DimGray"/>
</StackPanel>
</Grid>
</DataTemplate>
</Page.Resources>
<Page.BottomAppBar>
<CommandBar Background="Transparent">
<AppBarButton Icon="Add" Label="Add" Click="add_onclick"/>
<AppBarButton Icon="Add" Label="Shake it!" />
</CommandBar>
</Page.BottomAppBar>
<Grid x:Name="LayoutRoot">
<Hub x:Name="Hub" x:Uid="Hub" Header="diary app hub" Margin="0,0,0,-59" Foreground="DimGray">
<Hub.Background>
<ImageBrush ImageSource="ms-appx:/Assets/desk_paper.png" Stretch="None"/>
</Hub.Background>
<!--<HubSection x:Uid="HubSection1" Header="SECTION 1" DataContext="{Binding Groups}" HeaderTemplate="{ThemeResource HubSectionHeaderTemplate}">
<DataTemplate>
<ListView
ItemsSource="{Binding}"
IsItemClickEnabled="True"
ItemClick="GroupSection_ItemClick"
ContinuumNavigationTransitionInfo.ExitElementContainer="True">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Margin="0,0,0,27.5">
<TextBlock Text="{Binding Title}" Style="{ThemeResource ListViewItemTextBlockStyle}" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</DataTemplate>
</HubSection>-->
<HubSection x:Uid="HubSection5" Header="Recent"
DataContext="{Binding Groups[0]}" HeaderTemplate="{ThemeResource HubSectionHeaderTemplate}">
<DataTemplate>
<ListView
AutomationProperties.AutomationId="ItemListViewSection5"
AutomationProperties.Name="Items In Group"
SelectionMode="None"
IsItemClickEnabled="True"
ItemsSource="{Binding Items}"
ItemTemplate="{StaticResource StandardDoubleLineItemTemplate}"
ItemClick="ItemView_ItemClick"
ContinuumNavigationTransitionInfo.ExitElementContainer="True">
</ListView>
</DataTemplate>
</HubSection>
<HubSection x:Uid="HubSection2" Header="All notes" Width ="Auto"
DataContext="{Binding Groups[0]}" HeaderTemplate="{ThemeResource HubSectionHeaderTemplate}" Height="659" >
<DataTemplate>
<GridView
Margin="0,9.5,0,0"
ItemsSource="{Binding Items}"
AutomationProperties.AutomationId="ItemGridView"
AutomationProperties.Name="Items In Group"
ItemTemplate="{StaticResource Standard200x180TileItemTemplate}"
SelectionMode="None"
IsItemClickEnabled="True"
ItemClick="ItemView_ItemClick"
ContinuumNavigationTransitionInfo.ExitElementContainer="True">
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<ItemsWrapGrid />
</ItemsPanelTemplate>
</GridView.ItemsPanel>
</GridView>
</DataTemplate>
</HubSection>
</Hub>
</Grid>
You need to raise the PropertyChanged event for the model's properties. The UI doesn't get notified as properties like Title,Subtitle don't raise the PropertyChanged event when they are modified. It should be like this:
private string _title;
public string Title
{
get
{
return _title;
}
set
{
if(_title!=value)
{
_title=value;
OnPropertyChanged("Title");
}
}
}
Do this similarly for other properties. Also, you don't need to raise the PropertyChanged event for an ObservableCollection as an ObservableCollection implements INotifyPropertyChanged by default.
So, I am on my way learning MVVM Pattern for Windows Phone, and stuck how to bind the View to my ViewModel. App that I build now is getting current and next 5 days weather and display it to one of my panorama item on MainPage.xaml using UserControl.
I cannot just simply set the Forecasts.ItemsSource = forecast; in my WeatherViewModel, it says that Forecasts (Listbox element name in WeatherView) not exist in the current context.
Can anybody teach me how to bind it? and anybody have a good source/example sample to mvvm pattern in windows-phone? Thanks before.
EDIT:
WeatherModel.cs
namespace JendelaBogor.Models
{
public class WeatherModel
{
public string Date { get; set; }
public string ObservationTime { get; set; }
public string WeatherIconURL { get; set; }
public string Temperature { get; set; }
public string TempMaxC { get; set; }
public string TempMinC { get; set; }
public string Humidity { get; set; }
public string WindSpeedKmph { get; set; }
}
}
WeatherViewModel.cs
namespace JendelaBogor.ViewModels
{
public class WeatherViewModel : ViewModelBase
{
private string weatherURL = "http://free.worldweatheronline.com/feed/weather.ashx?q=";
private const string City = "Bogor,Indonesia";
private const string APIKey = "APIKEY";
private IList<WeatherModel> _forecasts;
public IList<WeatherModel> Forecasts
{
get
{
if (_forecasts == null)
{
_forecasts = new List<WeatherModel>();
}
return _forecasts;
}
private set
{
_forecasts = value;
if (value != _forecasts)
{
_forecasts = value;
this.NotifyPropertyChanged("Forecasts");
}
}
}
public WeatherViewModel()
{
WebClient downloader = new WebClient();
Uri uri = new Uri(weatherURL + City + "&num_of_days=5&extra=localObsTime&format=xml&key=" + APIKey, UriKind.Absolute);
downloader.DownloadStringCompleted += new DownloadStringCompletedEventHandler(ForecastDownloaded);
downloader.DownloadStringAsync(uri);
}
private void ForecastDownloaded(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Result == null || e.Error != null)
{
MessageBox.Show("Cannot load Weather Forecast!");
}
else
{
XDocument document = XDocument.Parse(e.Result);
var current = from query in document.Descendants("current_condition")
select new WeatherModel
{
ObservationTime = DateTime.Parse((string)query.Element("localObsDateTime")).ToString("HH:mm tt"),
Temperature = (string)query.Element("temp_C"),
WeatherIconURL = (string)query.Element("weatherIconUrl"),
Humidity = (string)query.Element("humidity"),
WindSpeedKmph = (string)query.Element("windspeedKmph")
};
this.Forecasts = (from query in document.Descendants("weather")
select new WeatherModel
{
Date = DateTime.Parse((string)query.Element("date")).ToString("dddd"),
TempMaxC = (string)query.Element("tempMaxC"),
TempMinC = (string)query.Element("tempMinC"),
WeatherIconURL = (string)query.Element("weatherIconUrl")
}).ToList();
}
}
}
}
WeatherView.xaml
<UserControl x:Class="JendelaBogor.Views.WeatherView"
xmlns:vm="clr-namespace:JendelaBogor.ViewModels">
<UserControl.DataContext>
<vm:WeatherViewModel />
</UserControl.DataContext>
<Grid Margin="0,-10,0,0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid x:Name="Current" Grid.Row="0" Height="150" VerticalAlignment="Top">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="150"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Image Grid.Column="0" delay:LowProfileImageLoader.UriSource="{Binding WeatherIconURL}" Width="120" Height="120" VerticalAlignment="Top"/>
<StackPanel Grid.Column="1" Height="200" VerticalAlignment="Top">
<TextBlock Text="{Binding Temperature}" FontSize="22"/>
<TextBlock Text="{Binding ObservationTime}" FontSize="22"/>
<TextBlock Text="{Binding Humidity}" FontSize="22"/>
<TextBlock Text="{Binding Windspeed}" FontSize="22"/>
</StackPanel>
</Grid>
<Grid Grid.Row="1" Height="300" VerticalAlignment="Bottom" Margin="10,0,0,0">
<StackPanel VerticalAlignment="Top">
<StackPanel Height="40" Orientation="Horizontal" Margin="0,0,0,0">
<TextBlock Text="Date" FontSize="22" Width="170"/>
<TextBlock Text="FC" FontSize="22" Width="60"/>
<TextBlock Text="Max" TextAlignment="Right" FontSize="22" Width="90"/>
<TextBlock Text="Min" TextAlignment="Right" FontSize="22" Width="90"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<ListBox ItemsSource="{Binding Forecasts}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Height="40" Orientation="Horizontal" Margin="0,10,0,0">
<TextBlock Text="{Binding Date}" FontSize="22" TextAlignment="Left" Width="170" />
<Image delay:LowProfileImageLoader.UriSource="{Binding WeatherIconURL}" Width="40" Height="40" />
<TextBlock Text="{Binding TempMaxC, StringFormat='\{0\} °C'}" TextAlignment="Right" FontSize="22" Width="90" />
<TextBlock Text="{Binding TempMinC, StringFormat='\{0\} °C'}" TextAlignment="Right" FontSize="22" Width="90" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</StackPanel>
</Grid>
</Grid>
</UserControl>
MainPage.xaml
<controls:PanoramaItem x:Name="Weather" Header="weather">
<views:WeatherView />
</controls:PanoramaItem>
You need to tell the view what viewmodel you are using. By adding
<UserControl
xmlns:vm="clr-namespace:JendelaBogor.ViewModels">
<UserControl.DataContext>
<vm:WeatherViewModel />
</UserControl.DataContext>
</UserControl>
all {Binding}'s are mapped to the class WeatherViewModel. By using the ItemsSource property on the listbox as Reed suggests you can then bind all items from a list that you expose through a property.
If the list is ever changed while running the application, consider using an ObservableCollection and clearing it and adding all new items when new data is received. If you do, your GUI will simply update with it.
The ViewModel doesn't know about the view.
You need to make a Forecasts property on the ViewModel, and bind the ItemsSource to it from your View. In your view, change the ListBox to:
<!-- No need for a name - just add the binding -->
<ListBox ItemsSource="{Binding Forecasts}">
Then, in your ViewModel, add:
// Add a backing field
private IList<WeatherModel> forecasts;
// Add a property implementing INPC
public IList<WeatherModel> Forecasts
{
get { return forecasts; }
private set
{
forecasts = value;
this.RaisePropertyChanged("Forecasts");
}
}
You can then set this in your method:
this.Forecasts = (from query in document.Descendants("weather")
select new WeatherModel
{
Date = DateTime.Parse((string)query.Element("date")).ToString("dddd"),
TempMaxC = (string)query.Element("tempMaxC"),
TempMinC = (string)query.Element("tempMinC"),
WeatherIconURL = (string)query.Element("weatherIconUrl")
})
.ToList(); // Turn this into a List<T>