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creating dynamic controls with MVVM

I am trying to create a dynamic control with using mvvm for the first time. I want to generate buttons dynamically and have the content display inside of the buttons. I am sure I am missing something really easy here, but I have no idea what it could be. When I run the code, nothing appears on the interface, though I can see AvailableMonitorOC populate in the constructor...
Here is my ViewModel where I manually add buttons to an observable collection for simplicity sake of this example:
public class CreateAndDisplayViewModel {
public ObservableCollection<AvailableMonitorBo> AvailableMonitorOC = new ObservableCollection<AvailableMonitorBo>();
public CreateAndDisplayViewModel() {
availableMonitorBo = new AvailableMonitorBo();
availableMonitorBo.AvailableMonitorLabel = "Label 1";
AvailableMonitorOC.Add(availableMonitorBo);
availableMonitorBo.AvailableMonitorLabel = "Label 2";
AvailableMonitorOC.Add(availableMonitorBo);
}
private AvailableMonitorBo availableMonitorBo;
public AvailableMonitorBo AvailableMonitorBo {
get { return availableMonitorBo; }
set {
availableMonitorBo = value;
}
}
}
Here is my model:
public class AvailableMonitorBo : INotifyPropertyChanged {
private string availableMonitorLabel { get; set; }
public string AvailableMonitorLabel {
get { return availableMonitorLabel; }
set {
availableMonitorLabel = value;
OnPropertyChanged("AvailableMonitorLabel");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName) {
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) {
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
And here is the xaml:
<ListView Grid.Row="2" Grid.Column="1"
ItemsSource="{Binding AvailableMonitorOC, Mode=TwoWay}">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel>
<Button Content="{Binding AvailableMonitorLabel}"
Width="100"
Height="25"/>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

The main reason for you lack of display is that AvailableMonitorOC needs to be a property of CreateAndDisplayViewModel, not a field as it is currently.
You're also only creating one AvailableMonitorBo instance and changing its caption each time.

WPF ~ Trouble with Binding & INotifyPropertyChanged

WPF n00bie here, trying to get his UI to work properly.
So I made this test example. The textblock bound to HeaderText1 changes correctly at the launch of the app, but the textblock bound to HeaderText2 doesn't update after clicking the button.
What am I doing wrong? Thanks in advance!!
<Window x:Class="DataBinding.DataContextSample"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="DataContextSample" Height="142.596" Width="310">
<StackPanel Margin="15">
<WrapPanel>
<TextBlock Text="Window title: " />
<TextBox Name="txtWindowTitle" Text="{Binding Title, UpdateSourceTrigger=Explicit}" Width="150" />
<Button Name="btnUpdateSource" Click="btnUpdateSource_Click" Margin="5,0" Padding="5,0">*</Button>
</WrapPanel>
<TextBlock Text="{Binding Path=DataContext.HeaderText}"></TextBlock>
<TextBlock Text="{Binding Path=DataContext.HeaderText2}"></TextBlock>
</StackPanel>
</Window>
Main window class:
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
namespace DataBinding
{
public partial class DataContextSample : Window
{
public string HeaderText { set; get; }
public DataContextSample()
{
HeaderText = "YES";
InitializeComponent();
this.DataContext = this;
}
private void btnUpdateSource_Click(object sender, RoutedEventArgs e)
{
BindingExpression binding = txtWindowTitle.GetBindingExpression(TextBox.TextProperty);
binding.UpdateSource();
Source source = new Source();
source.HeaderText2 = "YES2";
}
}
}
And the INotifyPropertyChanged class
using System.ComponentModel;
namespace DataBinding
{
public class Source : INotifyPropertyChanged
{
public string HeaderText2 { set; get; }
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
}
}

First of all you are doing many things wrong.
You should not be using the window as it's own datacontext, you should have a viewmodel that you set.
You should not be using event handlers in the view to manipulate the viewmodel. You should bind the button to a command.
Your source seems to be a "viewmodel", consider renaming it to MainWindowViewModel (for clarity) and then do this.
public class MainWindowViewModel : INotifyPropertyChanged
{
private string headerText;
private string headerText2;
private ICommand updateHeaderText2;
public string HeaderText
{
set
{
return this.headerText;
}
get
{
this.headerText = value;
// Actually raise the event when property changes
this.OnPropertyChanged("HeaderText");
}
}
public string HeaderText2
{
set
{
return this.headerText2;
}
get
{
this.headerText2 = value;
// Actually raise the event when property changes
this.OnPropertyChanged("HeaderText2");
}
}
public ICommand UpdateHeaderText2
{
get
{
// Google some implementation for ICommand and add the MyCommand class to your solution.
return new MyCommand (() => this.HeaderText2 = "YES2");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
}
And set this viewmodel to the datacontext of your window.
this.DataContext = new MainWindowViewModel();
And then in your xaml you should bind to the viewmodel as such
<Window x:Class="DataBinding.DataContextSample"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="DataContextSample" Height="142.596" Width="310">
<StackPanel Margin="15">
<WrapPanel>
<TextBlock Text="Window title: " />
<!-- Not sure what this binding is? -->
<TextBox Name="txtWindowTitle" Text="{Binding Title, UpdateSourceTrigger=Explicit}" Width="150" />
<Button Name="btnUpdateSource" Command="{Binding UpdateHeaderText2}" Margin="5,0" Padding="5,0">*</Button>
</WrapPanel>
<TextBlock Text="{Binding HeaderText}"></TextBlock>
<TextBlock Text="{Binding HeaderText2}"></TextBlock>
</StackPanel>
</Window>

You set the DataContext to this (the window). You don't have a property named HeaderText2 in the DataContext so the second binding won't work.
I'd do this (without changing your code too much, in reality I'd do a proper MVVM approach):
public partial class DataContextSample : Window
{
public Source Source { get; set; }
public string HeaderText { set; get; }
public MainWindow()
{
InitializeComponent();
HeaderText = "YES";
Source = new Source { HeaderText2 = "YES" };
DataContext = this;
}
private void btnUpdateSource_Click(object sender, RoutedEventArgs e)
{
BindingExpression binding = txtWindowTitle.GetBindingExpression(TextBox.TextProperty);
if (binding != null)
{
binding.UpdateSource();
}
Source.HeaderText2 = "YES2";
}
}
I added a new property called Source which is of type Source. Set its initial HeaderText2 to the same "YES" in the constructor and in the button click change that to "YES2".
You have to change your Source class as well, to actually notify about changes:
public class Source : INotifyPropertyChanged
{
private string _headerText2;
public string HeaderText2
{
get { return _headerText2; }
set
{
_headerText2 = value;
OnPropertyChanged("HeaderText2");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
}
And then in your XAML:
<StackPanel Margin="15">
<WrapPanel>
<TextBlock Text="Window title: " />
<TextBox Name="txtWindowTitle" Text="{Binding Title, UpdateSourceTrigger=Explicit}" Width="150" />
<Button Name="btnUpdateSource" Click="btnUpdateSource_Click" Margin="5,0" Padding="5,0">*</Button>
</WrapPanel>
<TextBlock Text="{Binding Path=HeaderText}"></TextBlock>
<TextBlock Text="{Binding Path=Source.HeaderText2}"></TextBlock>
</StackPanel>

Well there are a few issues with your code.
First of all, you never assign your "Source" to a datacontext, so there's no way for your second TextBlock to find the value of "HeaderText2".
If however you would assign your "Source" to the textblocks datacontext then we could fetch the value of "HeaderText2". Consider the code below
<Window x:Class="DataBinding.DataContextSample"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="DataContextSample" Height="142.596" Width="310">
<StackPanel Margin="15">
<WrapPanel>
<TextBlock Text="Window title: " />
<TextBox Name="txtWindowTitle" Text="{Binding Title, UpdateSourceTrigger=Explicit}" Width="150" />
<Button Name="btnUpdateSource" Click="btnUpdateSource_Click" Margin="5,0" Padding="5,0">*</Button>
</WrapPanel>
<TextBlock Text="{Binding Path=HeaderText}"></TextBlock>
<TextBlock Name="TextBlock2" Text="{Binding Path=HeaderText2}"></TextBlock>
</StackPanel>
</Window>
We have given your second Textblock a name, "TextBlock2" and also removed the "Datacontext"-part from your binding.
Then we have moved the Creation of your "Source" object from the button event to the windows constructor (there is no need to make a new one everytime we click a button when all we want to do is to update a property)
public partial class DataContextSample : Window
{
public string HeaderText { set; get; }
private Source source { get; set; }
public DataContextSample()
{
...
source = new Source();
TextBlock2.DataContext = source;
...
}
...
}
And then in your buttons click-event we assign your databound property a value of "YES2".
private void btnUpdateSource_Click(object sender, RoutedEventArgs e)
{
...
source.HeaderText2 = "YES2";
}
There is however one more detail. Your class "Source" does implement "INotifyPropertyChanged", but it never "uses" it. By that I mean, that when you assign a value to your property "HeaderText2" you never actually "notify" the UI that something has changed with it, and thus the UI will not fetch the new value. Consider the code below:
public class Source : INotifyPropertyChanged
{
public string HeaderText2 { set
{
headerText2 = value;
OnPropertyChanged("HeaderText2");
}
get
{
return headerText2;
}
}
string headerText2;
...
}
So let's take a look at what we've done with the property "HeaderText2". Everytime the "HeaderText2" gets a value assigned, it will first save the value in a privat property (so that we can read from it later). But in addition to that we also call the "OnPropertyChanged" method with our Propertys name. That method will in turn check if anyone is "listening" to our "PropertyChanged"-event (and since we have a databinding on the current object, someone is listening), and create a new event.
Now we have assigned a datasource to your textblock with a path to "HeaderText2", we are notifying all listeners when we update "HeaderText2" on the datasource and we are updating "HeaderText2" on the buttons click event.
Happy coding!

Simple XAML binding in a textblock text

I have a TextBlock control inside a HubSection in a Windows 8.1 Universal app.
<TextBlock x:Name="api_enabled_label"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
Text="{Binding APIinfotext}" />
Now when the page is launched, in the contrustor, there is a method that is run.
public string APIinfotext { get; set; }
public sealed partial class MainPage : Page {
VoipMS voip_service = new VoipMS("shoukatali#hotmail.com", "Kitt0cat");
public string APIinfotext { get; set; }
public MainPage() {
this.InitializeComponent();
// disable sections until API is enabled
mainpagehub.Sections[1].IsEnabled = false;
mainpagehub.Sections[2].IsEnabled = false;
//check for API and enable sections
checkAPI();
}
private async void checkAPI() {
//irrelevant code above
switch (result) {
case "success":
APIinfotext = "Your API is connected";
break;
//irrelevant code below
}
}
So why dosnt this work? I set the DataContext of the Textblock to the current class (which is the MainPage partial class) and the property is a public property.
Note: Today is my first time working with .net 4.5 with XAML after a huge break at the .net 2.0 framework with WinForms.

Your binding doesn't know that APIinfotext property has changed. To let the bindings know that the property has changed you can do one of the following. The first one is the easiest.
1) implement INotifyPropertyChanged interface and raise the PropertyChanged changed event once APIinfotext has changed (PropertyChanged("APIinfotext"));
2) Have an event called APIinfotextChanged with the standard event signature and raise that event after the property has changed.
3) Implement your property as a DependencyProperty (not an ideal solution in this case).

You might be missing the part where you have to RaiseProperyChange NotifyPropertyChage to update the bindings. your Model should implement the INotifyPropertyChanged interface
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
then
RaisePropertyChanged("APIinfotext");
http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.propertychanged.aspx

Looks like you need a very simple example of what the other two are talking about. Let's assume nothing. You need to set the DataContext correctly, plus raise the event. This is as simple as I can put it, when you click on the button it will change the TextBox because I change the Property which raises the event.
XAML
<Page>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<StackPanel>
<TextBox Text="{Binding APIinfotext}" Height="100" Width="400" HorizontalAlignment="Left"/>
<Button x:Name="myButton" Content="Change Text" Height="200" Width="400" Click="myButton_Click"/>
</StackPanel>
</Grid>
</Page>
C# (Pay attention, to the SET part of the APIinfotext)
using System.ComponentModel; // INotifyPropertyChanged
public sealed partial class MainPage : Page, INotifyPropertyChanged
{
private string _apiinfotext = "Default Text";
public string APIinfotext
{
get { return _apiinfotext; }
set
{
_apiinfotext = value;
RaisePropertyChanged("APIinfotext");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
public MainPage()
{
this.InitializeComponent();
this.DataContext = this;
}
private void myButton_Click(object sender, RoutedEventArgs e)
{
this.APIinfotext = "Don't confuse movement for progress.";
}
}

WPF data binding with inner elements

I want to bind my StackPanel component to an object and its properties to elements it the StackPanel
<StackPanel Grid.Column="0" Grid.Row="0" Name="device1" Background="#CC119EDA" DataContext="{Binding}">
<Label FontSize="22" Foreground="White">Desk #1</Label>
<TextBox Text="{Binding Name}" />
</StackPanel>
In code behind
device1.DataContext = new Class { Name = "Name" };
What is wrong with this binding? Thanks

You could try like this. When u set the property to the Object , the UI Thread is not aware of the change , so you need to Implement RaisePropertyChange Mechanism. Using MvvmLight Toolkit is great advantage . Here the window datacontext is set to so could inherit all elements.
public partial class MainWindow : Window, INotifyPropertyChanged
{
private string _name;
public string MyName
{
get { return _name; }
set
{
_name = value;
OnPropertyChanged("MyName");
}
}
public MainWindow()
{
InitializeComponent();
MyName = "Eldho";
this.DataContext = this;
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
Xaml
<StackPanel>
<Label>Hi,</Label>
<TextBox Text="{Binding MyName}"/>
</StackPanel>

No binding Value Property of Slider in Windows Phone 8

I'm new to programming in Windows Phone 8. I am studying "The Binding". I try to bind the property "Value" of a Slider, but when running the application I do not see any change.
The XAML code is this:
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<StackPanel>
<Slider Minimum="1" Maximum="100" Value="{Binding Valor}" />
</StackPanel>
</Grid>
The ViewModelBase class is this:
public class VMBase : INotifyPropertyChanged {
public event PropertyChangedEventHandler PropertyChanged;
public VMBase() {}
public void RaisePropertyChanged(string PropertyName) {
if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));
}
}
The ViewModel class is this:
public class VMSlider : VMBase {
private int _valor;
public VMSlider() {
_valor = 43;
}
public int Valor {
get { return _valor; }
set {
_valor = value;
RaisePropertyChanged("Valor");
}
}
}
In the code-behind class of my XAML y write this:
this.DataContext = new ViewModel.VMSlider();
I need to say why.
Thank you.

The Value property on the Slider control is of type Double. Your Binding doesn't work because Valor is a value of the wrong type.
You must either implement a Value Converter or change Valor to a Double.