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How do i make a UIElement change when a propertie change?

I am trying to make a really simple app to learn DataBinding and events. The following code is supposed to change the label content when i click on a button, but actually it changes the property but doesn't update the label.
This is the main code :
public MainWindow()
{
InitializeComponent();
environments = new ObservableCollection<Env>();
environments.Add(new Env("env1", new ObservableCollection<Cell>()));
environments.Add(new Env("env2", new ObservableCollection<Cell>()));
foreach (Env e in environments)
{
Label label = new Label
{
Content = e.Name
};
pnlMain.Children.Add(label);
}
}
private void ChangeEnvName_Click(object sender, RoutedEventArgs e)
{
foreach (Env env in environments)
{
env.Name = "test";
}
}
And this is the Env class :
class Env : INotifyPropertyChanged
{
//membres
#region membres
private string _name;
private ObservableCollection<Cell> _cells;
#endregion
//propriétés
#region propriétés
public string Name
{
get { return this._name; }
set
{
if (this._name != value)
{
this._name = value;
this.NotifyPropertyChanged("Name");
}
}
}
public ObservableCollection<Cell> Cells
{
get { return this._cells; }
set
{
if (this._cells != value)
{
this._cells = value;
this.NotifyPropertyChanged("Cells");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
#endregion
//méthodes
#region méthodes
public void NotifyPropertyChanged(string propName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
#endregion
//constructeur
#region contructeur
public Env(string name, ObservableCollection<Cell> cells)
{
_name = name;
_cells = cells;
}
#endregion
}
What's the problem? Isn't it suppose the update the label.content when i update Env.Name ?

You haven't bound the Content property of the Label to the Name property. You have just set it to a string. Try this:
foreach (Env e in environments)
{
Label label = new Label();
label.SetBinding(Label.ContentProperty, new Binding("Name") { Source = e });
pnlMain.Children.Add(label);
}
Or create an Environments property that returns environments, set the DataContext to this and bind to Environments[index].Name. If you don specify an explicit Source of the binding, it will look for the property in its current DataContext which may be inherited from a parent element. Please see the docs for more information.

Why can't I reflect a list box choice in a text box in WPF?

I'm new to WPF and I'm having some trouble with my existing setup to get the list box selected item to appear in the text box.
The picture here represents the issue. I typed "12 HOUR" in the text box, which then filters the listbox to those items with "12 HOUR" anywhere in the string. But when I click "12 Hour Nasal" in the list box, I now want to reflect that choice back in the text box:
http://i.imgur.com/ZCYAolT.png
Here is my XAML for the user control containing the listbox and textbox:
<UserControl x:Class="SCM_AllergyRecModule.SearchAndSelectView"
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">
<StackPanel Width="300">
<TextBox x:Name="Filter" Text="{Binding Path=Filter, UpdateSourceTrigger=PropertyChanged}"/>
<ListBox Width ="300" Height="50" x:Name="ListBoxControl"
ItemsSource="{Binding Path=Allergens}"
SelectedItem="{Binding Path=SelectedAllergen}">
</ListBox>
</StackPanel>
And here is the ViewModel:
namespace SCM_AllergyRecModule
{
public class SearchAndSelectViewModel
{
private ICollectionView allergens;
private string selectedAllergen;
private string filter = "";
public string Filter
{
get
{
return this.filter.ToUpperInvariant();
}
set
{
if (this.filter != value)
{
this.filter = value;
this.Allergens.Refresh();
}
}
}
private bool ContainsFilter(object item)
{
var product = item as string;
if (product == null)
{
return false;
}
if (string.IsNullOrEmpty(this.Filter))
{
return true;
}
if (product.ToUpperInvariant().Contains(this.Filter))
{
return true;
}
return false;
}
public SearchAndSelectViewModel()
{
var cvs = new CollectionViewSource();
cvs.Source = MainWindow.scmAllergens;
this.allergens = cvs.View;
this.allergens.Filter = ContainsFilter;
}
public ICollectionView Allergens
{
get
{
return this.allergens;
}
}
public string SelectedAllergen
{
get
{
return this.selectedAllergen;
}
set
{
if (this.selectedAllergen != value)
{
this.selectedAllergen = value;
}
}
}
}
}
Update 1
I added the INotifyPropertyChanged interface to my class and have it being raised on SelectedAllergen in the setter. I added an event handler called SearchAndSelectViewModel_PropertyChanged to handle the SelectedAllergen property changing and set it in the constructor.
Now when I click an item in the listbox, I do see it setting the Filter to the SelectedItem and the list filters to that item so nothing else shows. But still, the text box text is not changing? See screenshot below. This is after I typed in "PEAN" in the textbox, then the listbox filtered to two choices, and I chose "PEANUTS (FOOD)", which then refiltered the list box to just show that choice but didn't set the text box to "PEANUTS (FOOD)":
http://imgur.com/dNxuVI5
Updated ViewModel
public class SearchAndSelectViewModel : INotifyPropertyChanged
{
private ICollectionView allergens;
private string selectedAllergen;
private string filter;
public string Filter
{
get
{
return this.filter.ToUpperInvariant();
}
set
{
if (this.filter != value)
{
this.filter = value;
this.Allergens.Refresh();
}
}
}
private bool ContainsFilter(object item)
{
var product = item as string;
if (product == null)
{
return false;
}
if (string.IsNullOrEmpty(this.Filter))
{
return true;
}
if (product.ToUpperInvariant().Contains(this.Filter))
{
return true;
}
return false;
}
private void SearchAndSelectViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
switch (e.PropertyName)
{
case "SelectedAllergen":
this.Filter = this.SelectedAllergen;
break;
}
}
public SearchAndSelectViewModel()
{
filter = "";
var cvs = new CollectionViewSource();
cvs.Source = MainWindow.scmAllergens;
this.allergens = cvs.View;
this.allergens.Filter = ContainsFilter;
this.PropertyChanged += SearchAndSelectViewModel_PropertyChanged;
}
public ICollectionView Allergens
{
get
{
return this.allergens;
}
}
public string SelectedAllergen
{
get
{
return this.selectedAllergen;
}
set
{
if (this.selectedAllergen != value && value != null)
{
this.selectedAllergen = value;
OnPropertyChanged("SelectedAllergen");
}
}
}
// INotifyPropertyChanged implementation
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}

You need to implement the INotifyPropertyChanged interface and you can raise it in your property setter. Since you are also binding your TextBox to the Filter property you need to set the Filter property when your SelectedAllergen changes.
INotifyPropertyChanged example:
public class MyViewModel : INotifyPropertyChanged
{
//...
private int myProperty = 0;
public int MyProperty
{
get { return myProperty; }
set
{
myProperty = value;
// Raise the property changed notification
OnPropertyChanged("MyProperty");
}
}
// INotifyPropertyChanged implementation
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if(handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}

How to filter table item by binding to checkbox ?

I have some table ( using ListView ) and i want to show in the table some object ( make filter ) if some checkbox is checked .... ( if the checkbox is not checked i want to show all the table items )
How can i do it by using mvvm ? I can't use the .cs file that bihind the xaml.
Thanks

here is a little example how it can works
code at your xaml, bind to the FilterItems property
<CheckBox Content="should i filter the view?" IsChecked="{Binding FilterItems}" />
<ListView ItemsSource="{Binding YourCollView}" />
code behond at your model view
public class MainModelView : INotifyPropertyChanged
{
public MainModelView()
{
var coll = new ObservableCollection<YourClass>();
yourCollView = CollectionViewSource.GetDefaultView(coll);
yourCollView.Filter += new Predicate<object>(yourCollView_Filter);
}
bool yourCollView_Filter(object obj)
{
return FilterItems
? false // now filter your item
: true;
}
private ICollectionView yourCollView;
public ICollectionView YourCollView
{
get { return yourCollView; }
set
{
if (value == yourCollView) {
return;
}
yourCollView = value;
this.NotifyPropertyChanged("YourCollView");
}
}
private bool _filterItems;
public bool FilterItems
{
get { return _filterItems; }
set
{
if (value == _filterItems) {
return;
}
_filterItems = value;
// filer your collection here
YourCollView.Refresh();
this.NotifyPropertyChanged("FilterItems");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String propertyName)
{
var eh = PropertyChanged;
if (eh != null) {
eh(this, new PropertyChangedEventArgs(propertyName));
}
}
}
EDIT
a complete example is located here
hope that helps

You can bind IsChecked property of checkbox in ViewModel. And in prpoperty setter you can filter your collection which gets binded to ListView.
XAML:
<CheckBox IsChecked="{Binding IsChecked}"/>
ViewModel:
private bool _isChecked;
public bool IsChecked
{
get
{
return _isChecked;
}
set
{
_isChecked = value;
//filer your collection here
}
}

INotifyPropertyChanged 'Double' binding

I'm trying to bind some XAML code to a property in my ViewModel.
<Grid Visibility="{Binding HasMovies, Converter={StaticResources VisibilityConverter}}">
...
</Grid>
My ViewModel is setup like this:
private bool _hasMovies;
public bool HasMovies
{
get { return _hasMovies; }
set { _hasMovies = value; RaisePropertyChanged("HasMovies"); }
}
In the constructor of the ViewModel, I set the HasMovies link:
MovieListViewModel()
{
HasMovies = CP.Connection.HasMovies;
}
in CP:
public bool HasMovies
{
get { return MovieList != null && MovieList.Count > 0; }
}
private ObservableCollection<Movie> _movies;
public ObservableCollection<Movie> MovieList
{
get { return _movies; }
set
{
_movies = value;
RaisePropertyChanged("MovieList");
RaisePropertyChanged("HasMovies");
_movies.CollectionChanged += MovieListChanged;
}
}
private void MovieListChanged(object sender, NotifyCollectionChangedEventArgs e)
{
RaisePropertyChanged("HasMovies");
}
What am I doing wrong? How should I change this binding so that it reflects the current state of CP.Connection.HasMovies?

Either directly expose the object in the ViewModel and bind directly through that (so that the value is not just copied once which is what happens now) or subscribe to the PropertyChanged event and set HasMovies to the new value every time it changes in your source object.
e.g.
CP.Connection.PropertyChanged += (s,e) =>
{
if (e.PropertyName = "HasMovies") this.HasMovies = CP.Connection.HasMovies;
};

First of all, the setter for a collection type, such as your MovieList property, is not called when you change the content of the collection (ie. Add/Remove items).
This means all your setter code for the MovieList property is pointless.
Secondly, it's very silly code. A much better solution, is to use NotifyPropertyWeaver. Then your code would look like this, in the viewmodel:
[DependsOn("MovieList")]
public bool HasMovies
{
get { return MovieList != null && MovieList.Count > 0; }
}
public ObservableCollection<Movie> MovieList
{
get;
private set;
}
Alternatively you would have to add a listener for the CollectionChanged event when you initialize the MovieList property the first time (no reason to have a backing property, really really no reason!), and then call RaisePropertyChanged("HasMovies") in the event handler.
Example:
public class CP : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public CP()
{
MovieList = new ObservableCollection<Movie>();
MovieList.CollectionChanged += MovieListChanged;
}
public bool HasMovies
{
get { return MovieList != null && MovieList.Count > 0; }
}
public ObservableCollection<Movie> MovieList
{
get;
private set;
}
private void MovieListChanged(object sender, NotifyCollectionChangedEventArgs e)
{
RaisePropertyChanged("HasMovies");
}
private void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}

RadioButton binding in Windows Forms with INotifyPropertyChanged?

I am trying to bind some RadioButtons to booleans in a class which in-turn enable/disable other elements on the form. For example:
x radioButton1
x checkBox1
x radioButton2
x checkBox2
I want to enable checkBox1 only when radioButton1 is selected and likewise for radioButton2 and checkBox2.
When I try to bind these it takes two clicks to change a RadioButton selection. It seems like the order of binds is causing a logic issue.
Here is code that shows this. The form is just two default named RadioButtons and two CheckBoxes.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
BindingSource bindingSource = new BindingSource(new Model(), "");
radioButton1.DataBindings.Add(new Binding("Checked", bindingSource, "rb1Checked", true, DataSourceUpdateMode.OnPropertyChanged));
radioButton2.DataBindings.Add(new Binding("Checked", bindingSource, "rb2Checked", true, DataSourceUpdateMode.OnPropertyChanged));
checkBox1.DataBindings.Add(new Binding("Enabled", bindingSource, "cb1Enabled", true, DataSourceUpdateMode.OnPropertyChanged));
checkBox2.DataBindings.Add(new Binding("Enabled", bindingSource, "cb2Enabled", true, DataSourceUpdateMode.OnPropertyChanged));
}
}
public class Model : INotifyPropertyChanged
{
private bool m_rb1Checked;
public bool rb1Checked
{
get { return m_rb1Checked; }
set
{
m_rb1Checked = value;
NotifyPropertyChanged("cb1Enabled");
}
}
private bool m_rb2Checked;
public bool rb2Checked
{
get { return m_rb2Checked; }
set
{
m_rb2Checked = value;
NotifyPropertyChanged("cb2Enabled");
}
}
public bool cb1Enabled { get { return rb1Checked; } }
public bool cb2Enabled { get { return rb2Checked; } }
public Model()
{
rb1Checked = true;
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string fieldName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(fieldName));
}
}
#endregion
}
Anyone see a way to make this work?

This appears to be a bug and won't be fixed:
http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/5735dac2-63e9-4797-80af-91969bf4d16e/
As a workaround, I "manually" hooked up the binding like this:
// Set initial values
radioButton1.Checked = model.Checked;
radioButton2.Checked = model.Checked;
// Change on event
radioButton1.CheckedChanged += delegate { model.rb1Checked = radioButton1.Checked; };
radioButton2.CheckedChanged += delegate { model.rb2Checked = radioButton2.Checked; };
// These stay the same
checkBox1.DataBindings.Add(new Binding("Enabled", bindingSource, "cb1Enabled", true, DataSourceUpdateMode.OnPropertyChanged));
checkBox2.DataBindings.Add(new Binding("Enabled", bindingSource, "cb2Enabled", true, DataSourceUpdateMode.OnPropertyChanged));

For me BT's answer was not enough. I had to add manual checking of which button was clicked, otherwise it still needed 2 clicks for radiobuttons.
this.ViewModel = new FancyClassViewModel();
this.radioButton1.CheckedChanged +=
delegate { this.ViewModel.Radio1Checked = this.radioButton1.Checked; };
this.radioButton2.CheckedChanged +=
delegate { this.ViewModel.Radio2Checked = this.radioButton2.Checked; };
this.ViewModel.PropertyChanged += (sender, e) =>
{
if (e.PropertyName == "Radio1")
{
this.radioButton1.Checked = this.ViewModel.Radio1Checked;
}
if (e.PropertyName == "Radio2")
{
this.radioButton2.Checked = this.ViewModel.Radio2Checked;
}
};