I have recently started with XAML and WPF. I just created a new project in wpf and add the below XAML code. But...none of the items which are added inside "Listbox.ItemTemplate" or "ListView.ItemTemplate" for that matter show up in designer window. what am i doing wrong? This is a fresh project and so no code-behind stuff added yet. i scratched my head for 15 mins with this but with no success. Please help
<Window x:Class="WpfApplication3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid Margin="10">
<ListBox Margin="10">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Name: " />
<TextBlock Text="Age: " />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>
You should bind your ListBox or entire Window to some DataContext (usually this is viewmodel with the data you need to display) or specify items of the list explicitly.
In your snippet you specified only an item template, not the items itself.
The example of XAML-defined items (simple strings):
<Window x:Class="WpfApplication3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid Margin="10">
<ListBox Margin="10">
<ListBox.Items>
<ListBoxItem>123</ListBoxItem>
<ListBoxItem>456</ListBoxItem>
</ListBox.Items>
</ListBox>
</Grid>
</Window>
The example with DataContext and Bindings.
XAML:
<Window x:Class="WpfApplication3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid Margin="10">
<ListBox Margin="10" ItemsSource="{Binding Path=Persons}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Label>Name:</Label><TextBlock VerticalAlignment="Center" Text="{Binding Path=Name}" />
<Label>Age:</Label><TextBlock VerticalAlignment="Center" Text="{Binding Path=Age}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>
Codebehind:
namespace WpfApplication3
{
public class PersonViewModel
{
public PersonViewModel(string name, int age)
{
this.name = name;
this.age = age;
}
public string Name
{
get { return name; }
}
private string name;
public int Age
{
get { return age; }
}
private int age;
}
public class MainViewModel
{
public MainViewModel()
{
persons = new ObservableCollection<PersonViewModel>()
{
new PersonViewModel("Lez", 146),
new PersonViewModel("Binja", 158),
new PersonViewModel("Rufus the Destroyer", 9000)
};
}
public ObservableCollection<PersonViewModel> Persons
{
get { return persons; }
}
private ObservableCollection<PersonViewModel> persons;
}
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.DataContext = new MainViewModel();
}
}
}
IMPORTANT: Don't forget to properly implement INotifyPropertyChanged in case of mutable properties of viewmodels (for example, if you will have setters for "Name" and "Age" properties of PersonViewModel).
You don't see any items because your ListBox doesn't contain any data in the designer view. To populate it, a list should be binded to the property "ItemsSource" of your ListBox, or adding datas directly to the property "Items" (XAML or code behind).
If you want to show items in the designer view properly, you should have a ViewModel binding to the DataContext of your page and create a "Sample data" file (via Blend for example).
Item Templates are basically used to show customize data. Just Use simple string items first. It will show in list box.
Related
I have TabControl that has already define some TabItems on XAML. I need to create new TabItems and add to it.
If I use ItemSource I get an exception Items collection must be empty before using ItemsSource.
The solution I have found so far is to create those TabItems I have already defined on XAML but programmatically on the ViewModel, so I can created the others I really need, but doesn't seems to be a good solution.
Other solution would be to add the TabControl as a property and use the Code-Behind to bind it to the ViewModel, which I would like to avoid.
So, I'm just wondering if there is a way to do this only with XAML and MVVM.
Edit:
ItemSource attempt, which is working.
XAML:
<TabControl Grid.Row="1"
Grid.Column="0"
VerticalAlignment="Stretch"
BorderThickness="0.5"
BorderBrush="Black"
ItemsSource="{Binding Model.TabItems, Mode=TwoWay}">
<!--<TabControl.Items>
</TabControl.Items>-->
</TabControl>
Model
public ObservableCollection<TabItem> TabItems {get;set;}
VM
TabItem tabItem = new TabItem { Content = new DetailedViewModel((MyObject)inCommandParameter) };
Model.TabItems.Add(tabItem);
What you are doing here is NOT MvvM. Idea behind it is to keep parts of the app separate, i.e. Model should NOT return any UI elements. If you want to use this with any other UI framework for example WinForms then it will fail and will require additional work.
What you need is something like this, bear in mind that this is an example and you will need to modify this to comply with your requirements.
Model class:
namespace Model
{
public class Profile
{
public string Name { get; set; }
public static int I { get; set; } = 2;
}
}
After this you will need the ViewModel:
namespace VM
{
public class MainViewModel : BaseViewModel
{
public MainViewModel()
{
ProfilesCollection = new List<Profile>();
for (int i = 0; i < 100; i++)
{
ProfilesCollection.Add(new Profile() {Name = $"Name {i}"});
}
}
private List<Profile> profilesCollection;
public List<Profile> ProfilesCollection
{
get { return profilesCollection; }
set { profilesCollection = value; OnPropertyChanged(); }
}
}
}
Now we have base to work with. After that I assume you know how to add the relevant references in your xaml, but this might be seen by other people so I will include it anyway.
Here is a complete MainWindow.xaml:
<Window x:Class="SO_app.MainWindow"
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:vm="clr-namespace:VM;assembly=VM"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:converter="clr-namespace:SO_app.Converters"
xmlns:validation="clr-namespace:SO_app.Validation"
xmlns:scm="clr-namespace:System.ComponentModel;assembly=WindowsBase"
xmlns:local="clr-namespace:SO_app"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
xmlns:model="clr-namespace:Model;assembly=Model"//reference to my model
mc:Ignorable="d"
Title="MainWindow" Height="452.762" Width="525" Closing="Window_Closing">
<!-- d:DataContext="{d:DesignInstance Type=vm:MainViewModel, IsDesignTimeCreatable=True}" -->
<Window.Resources>
<CollectionViewSource Source="{Binding ProfilesCollection}" x:Key="profiles"/> // this corresponds to our collection in VM
</Window.Resources>
<Window.DataContext>
<vm:MainViewModel/>//Data Context of the Window
</Window.DataContext>
<Window.Background>
<VisualBrush>
<VisualBrush.Visual>
<Rectangle Width="50" Height="50" Fill="ForestGreen"></Rectangle>
</VisualBrush.Visual>
</VisualBrush>
</Window.Background>
<TabControl>
<TabControl.Resources>
<DataTemplate DataType="{x:Type model:Profile}">//this data template will be used by the TabControl
<Grid>
<TextBlock Text="{Binding Name}"/>
</Grid>
</DataTemplate>
</TabControl.Resources>
<TabControl.ItemsSource>
<CompositeCollection>
<TabItem Header="First Item"/>
<TabItem Header="SecondItem"/>
<CollectionContainer Collection="{Binding Source={StaticResource profiles}}"/>
</CompositeCollection>
</TabControl.ItemsSource>
</TabControl>
If you want to add more items then just use Command which would be implemented in VM and just add profile to it and enjoy the show.
Add collections of buttons in my userControl (Options).
In xaml disigner the are displayed.
Output
When i run my application:
If Options not initialized, then an error XamlObjectWriterException: Property collection "WpfAppUserControl.Buttons"."Options" (null).
If Options = new List(), then window without buttons
MainWindow.xaml
<Window x:Class="WpfAppUserControl.MainWindow"
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:local="clr-namespace:WpfAppUserControl"
mc:Ignorable="d"
Title="MainWindow" Height="250" Width="300">
<Grid>
<local:Buttons x:Name="Buttons"
VerticalAlignment="Center"
HorizontalAlignment="Center"
HorizontalContentAlignment="Center">
<local:Buttons.Options>
<Button Content="Agudabi 1" Height="20" Margin="2" />
<Button Content="Agudabi 2" Height="20" Margin="2" />
<Button Content="Agudabi 3" Height="20" Margin="2" />
</local:Buttons.Options>
</local:Buttons>
</Grid>
</Window>
Buttons.xaml
<UserControl x:Class="WpfAppUserControl.Buttons"
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"
xmlns:local="clr-namespace:WpfAppUserControl"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<WrapPanel x:Name="InternalContainer" Orientation="Horizontal" HorizontalAlignment="Center"/>
</Grid>
</UserControl>
Buttons.xaml.cs
#region Usings
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
#endregion
namespace WpfAppUserControl
{
public partial class Buttons : UserControl
{
public Buttons()
{
//Options = new ObservableCollection<Button>();
InitializeComponent();
}
public ObservableCollection<Button> Options
{
get { return (ObservableCollection<Button>) GetValue(OptionsProperty); }
set { SetValue(OptionsProperty, value); }
}
public static readonly DependencyProperty OptionsProperty =
DependencyProperty.Register(nameof(Options), typeof(ObservableCollection<Button>), typeof(Buttons),
new PropertyMetadata(/*new ObservableCollection<Button>()*/, PropertyChangedCallback));
private static void PropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var obj = d as Buttons;
foreach (var button in obj.Options)
{
obj.InternalContainer.Children.Add(button);
}
}
}
}
Here is an example of what you should actually do.
Instead of a UserControl with a collection property, use an ItemsControl like this:
<ItemsControl ItemsSource="{Binding Options}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Content="{Binding Name}" Command="{Binding Command}"
Height="20" Margin="2"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Then create a view model with a collection of data items with properties for the Button Content and Command:
public class ViewModel
{
public ObservableCollection<Option> Options { get; }
= new ObservableCollection<Option>();
}
public class Option
{
public string Name { get; set; }
public ICommand Command { get; set; }
}
Initialize it like shown below, where the ICommand implementation is ommited for brevity. Search the web for RelayCommand for a the implementation details.
public MainWindow()
{
InitializeComponent();
var vm = new ViewModel();
vm.Options.Add(new Option { Name = "Agudabi 1" });
vm.Options.Add(new Option { Name = "Agudabi 2" });
vm.Options.Add(new Option { Name = "Agudabi 3" });
DataContext = vm;
}
first initialize OptionsProperty with an empty ObservableCollection:
public partial class Buttons : UserControl
{
public Buttons()
{
Options = new ObservableCollection<Button>();
InitializeComponent();
}
public ObservableCollection<Button> Options
{
get { return (ObservableCollection<Button>) GetValue(OptionsProperty); }
set { SetValue(OptionsProperty, value); }
}
public static readonly DependencyProperty OptionsProperty =
DependencyProperty.Register("Options", typeof(ObservableCollection<Button>), typeof(Buttons));
}
Clemens commented that "Never set the default value of a collection type DP to anything else than null. Otherwise all instances of the UserControl class will operate on the same default collection instance." The same is true about any reference type. So property initialization is done in constructor.
you can do without PropertyChangedCallback, because it is possible to display collection more effectively using ItemsControl:
<UserControl x:Name="myUC" x:Class="WpfAppUserControl.Buttons"
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"
xmlns:local="clr-namespace:WpfAppUserControl"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<ItemsControl ItemsSource="{Binding Path=Options, ElementName=myUC}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel x:Name="InternalContainer" Orientation="Horizontal" HorizontalAlignment="Center"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</Grid>
</UserControl>
note that PropertyChangedCallback is not triggered when you add items to collections because collection property itself hasn't changed, it is the same reference
I'm trying to design the DataTemplate for my ItemsControl and I need some mock data to populate the template. I read using d:DataContext is enough so that I don't have to create a mock class. How can I do this?
The instance you have to use with d:DataContext must be declared in the XAML, with a StaticResource for example.
Here is how you could do it:
<UserControl x:Class="WpfApplication1.UserControl1"
xmlns:local="clr-namespace:WpfApplication1"
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">
<UserControl.Resources>
<local:MyViewModel x:Key="mockViewModel"/>
</UserControl.Resources>
<Grid>
<ItemsControl d:DataContext="{StaticResource mockViewModel}"
ItemsSource="{Binding Items}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
</UserControl>
The class I used as data context is defined as follows:
namespace WpfApplication1
{
public class Item
{
public Item(string name)
{
Name = name;
}
public string Name { get; private set; }
}
public class MyViewModel
{
public List<Item> Items
{
get
{
return new List<Item>() { new Item("Thing 1"), new Item("Thing 2") };
}
}
}
}
Of course, you can also set the data context on the UserControl or on your Window.
Here's the result:
I am currently working within a WPF user control using MVVM. My MainWindow.xaml looks like below.
MainWindow.xaml
<Window.Resources>
<ObjectDataProvider x:Key="TabsList" ObjectType="{x:Type local:MainWindowModel}" MethodName="GetTabs"/>
</Window.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<ListBox Grid.Column="0" ItemsSource="{Binding Source={StaticResource TabsList}}" IsSynchronizedWithCurrentItem="True">
<ListBox.ItemTemplate>
<DataTemplate>
<Label Content="{Binding Path=TabName}" Margin="10"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ContentControl Grid.Column="1" Content="{Binding Source={StaticResource TabsList}, Path=MyUserControl}"/>
</Grid>
Data provider class is as below
public class MainWindowModel
{
public List<TabInfo> GetTabs()
{
return new List<TabInfo>()
{
new TabInfo() { TabName="Tab1", MyUserControl = new UserControl1()},
new TabInfo() { TabName="Tab2", MyUserControl = new UserControl2()}
};
}
}
public class TabInfo
{
public string TabName { get; set; }
public UserControl MyUserControl { get; set; }
}
And now I have two usercontrols UserControl1 and UserControl2 each has a text box control. I would like to update the Text property of the textbox control in the UserControl1 whenever the Text property of the Textbox control in the UserControl2 is updated. To do this, I tried as below.
UserControl1
<UserControl x:Class="MoreOnBinding2.UserControl1"
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">
<Grid>
<TextBox Width="200" Height="20" Text="{Binding Path=UserControl1Text}"/>
</Grid>
UserControl1ViewModel
public class UserControl1VM : ViewModelBase
{
public UserControl1VM()
{
this.UserControl1Text = "10";
}
private string userControl1Text;
public string UserControl1Text
{
get { return userControl1Text; }
set
{
if (userControl1Text != value)
{
userControl1Text = value;
RaisePropertyChanged(() => UserControl1Text);
}
}
}
}
UserControl2
<UserControl x:Class="MoreOnBinding2.UserControl2"
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"
xmlns:local="clr-namespace:MoreOnBinding2"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<TextBox Width="200" Height="20"
Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type local:UserControl1}},
UpdateSourceTrigger=PropertyChanged, Path=UserControl1Text}" />
</Grid>
But it is not working. It seems there is a problem in the RelativeSource tag in the UserControl2. Can someone help on this.
You could use a Dependency Property on your user controls this would give you a bind able property. see link
EDIT 1
Just had another look at your class setup. If you are following the MVVM approach I don't think you should have a reference to your user control in your view model
View Model should be more Like
public Class
{
ObservableCollection<TabInfo> _Tabs = new ObservableCollection<TabInfo>();
public ObservableCollection<TabInfo> Tabs
{
get{return _Tabs;}
set {_Tabs = value;}//Need to implement INotifyPropertyChanged [Link][2]
}
public TabInfo SelectedTab {get;set;}
}
public class TabInfo
{
public string TabName { get; set; }
public UserControlViewModel MyUserControlViewModel{ get; set; }
}
Then in your View
<Window.DataContext>
<vm:MainWindowModel />
</Window.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<ListBox Grid.Column="0" ItemsSource="{Binding Tabs}" IsSynchronizedWithCurrentItem="True" SelectedValue="{Binding SelectedTab}">
<ListBox.ItemTemplate>
<DataTemplate>
<Label Content="{Binding Path=TabName}" Margin="10"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ContentControl Grid.Column="1" Content="{Binding SelectedTab.MyUserControlViewModel"/>
</Grid>
This should give you a list of Tabs and then when one is selected it will set the content of the ContentControl to the MyUserControlViewModel.
You would then need to use some sort of template selector to control the ContentTemplate to load different UserControls into the ContentControl
I haven't tested the code works and you would need to implement the INotifyPropertyChanged on all the public properties so the bindings update as the properties value is changed.
Hope that helps a bit.
We are using Resharper and of course we want to take advantage of Resharper's xaml intellisense.
Our View's Data Context are bound to a CurrentViewmodel property of type ViewModelBase. At runtime this Property is set with a View model inheritating from ViewModelBase.
I already added those lines in the View model to set the correct Type:
xmlns:vms="clr-namespace:PQS.ViewModel.Report"
d:DataContext="{d:DesignInstance vms:ReportFilterViewModel, IsDesignTimeCreatable=False}"
But Resharper still keeps looking in ViewModelbase for the Properties.
What else can i try?
Some more Code:
Setting the DataContext:
<UserControl.DataContext>
<Binding Path="ReportMainViewModel.CurrentVm" Source="{StaticResource Locator}"/>
</UserControl.DataContext>
Binding Something (Products is a Property on ReportFilterViewmodel, r# keeps looking for it in ViewModelBase):
<ListBox ItemsSource="{Binding Products.View}" Background="White" DisplayMemberPath="Name.ActualTranslation">
</ListBox>
R# can't statically find concrete view model type that will be available in runtime, so you need to annotate data context type manually like this:
using System.Collections.Generic;
public partial class MainWindow {
public MainWindow() {
Current = new ConcreteViewModel {
Products = {
new Product(),
new Product()
}
};
InitializeComponent();
}
public ViewModelBase Current { get; set; }
}
public class ViewModelBase { }
public class ConcreteViewModel : ViewModelBase {
public ConcreteViewModel() {
Products = new List<Product>();
}
public List<Product> Products { get; private set; }
}
public class Product {
public string ProductName { get { return "Name1"; } }
}
And XAML part:
<Window x:Class="MainWindow" x:Name="MainWin"
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:global="clr-namespace:" mc:Ignorable="d"
DataContext="{Binding ElementName=MainWin, Path=Current}">
<!-- here the type of data context is ViewModelBase -->
<Grid d:DataContext="{d:DesignInstance global:ConcreteViewModel}">
<!-- and here is ConcreteViewModel -->
<ListBox ItemsSource="{Binding Path=Products}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding ProductName}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>
Or like this:
<Window x:Class="MainWindow" x:Name="MainWin"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:global="clr-namespace:"
DataContext="{Binding ElementName=MainWin, Path=Current}">
<Grid>
<ListBox ItemsSource="{Binding Path=(global:ConcreteViewModel.Products)}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding ProductName}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>