Develop Reference

Unable to set Custom TreeView's Selected Item in Treeview programmtically

I created a WPF application where I create a list of items to be executed, as a Treeview. On a click event, I parse the ObservableCollection items one by one. This observableCollection is set as the DataContext for the treeview. When running the tests, I want to highlight the current running item in the Treeview.
I have the implemented following code, but the highlighting on the Treeview (visuallY) does not seem to happen. I checked that the "IsSelected" property does get set/unset as programmed.
I am not sure were I went wrong. Could you point out where the mistake is.
I have this class used as a DataContext to the TreeView (named mainTree).
class mytreefile : INotifyPropertyChanged
{
private string _name { get; set; }
public ObservableCollection <mytreefile> children { get; set; }
bool? _isSelected = false;
public bool? IsSelected
{
get { return _isSelected; }
set { SetIsSelected(value); }
}
void SetIsSelected(bool? val)
{
_isSelected = val;
}
public mytreefile(string value)
{
_name = value;
children = new ObservableCollection<mytreefile>();
}
void NotifyPropertyChanged(string info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
The XAML file is
<Grid.Resources>
<ResourceDictionary>
<HierarchicalDataTemplate x:Key="tvTemplate" ItemsSource="{Binding children, Mode=TwoWay}">
<StackPanel Orientation="Horizontal">
<ContentPresenter Content="{Binding _name, Mode=TwoWay}" Margin="2,0" />
</StackPanel>
</HierarchicalDataTemplate>
</ResourceDictionary>
</Grid.Resources>
<TreeView x:Name="mainTree" Grid.Row="0" Grid.Column="0" Grid.RowSpan="4" Background="WhiteSmoke"
Height="Auto" Width="Auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
HorizontalContentAlignment="Stretch"
Margin="1,0,2,0" SelectedItemChanged="mainTree_SelectedItemChanged"
ItemTemplate="{StaticResource tvTemplate}"
ItemsSource="{Binding}" DataContext="{Binding nodes}">
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding Path=IsSelected, Mode=TwoWay}" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
<Trigger Property="IsSelected" Value="False">
<Setter Property="FontWeight" Value="Normal" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
</TreeView>
And my MainWindow code is:
public partial class MainWindow : Window
{
ObservableCollection<mytreefile> nodes = new ObservableCollection<mytreefile>();
mytreefile mtf = null;
Thread thThread = null;
int gnCount = 0;
private void LoadTree ()
{
mytreefile tf1 = new mytreefile("Group1");
nodes.Add(tf1);
mytreefile subtf1 = new mytreefile("Sub Item 1");
mytreefile subtf2 = new mytreefile("Sub Item 2");
mytreefile subtf3 = new mytreefile("Sub Item 3");
mytreefile subtf4 = new mytreefile("Sub Item 4");
tf1.children.Add(subtf1); tf1.children.Add(subtf2); tf1.children.Add(subtf3); tf1.children.Add(subtf4);
maintree.DataContext = nodes;
}
private void OnButton1_click()
{
mtf = nodes.ElementAt(0);
gnCount = 0;
thThread = new Thread(new ThreadStart(this.myThread));
thThread.Start();
}
public void myThread ()
{
for (int i = 0; i < 3; i++)
{
Thread.Sleep(1000);
this.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Send,
new Action(() => SetTreeItem(i)));
}
}
public void SetTreeItem(int i)
{
if (gnCount > 0) {
mytreefile mtreeitem = mtf.children.ElementAt(gnCount-1);
mtreeitem.IsSelected = false;
}
mytreefile mtreeitem = mtf.children.ElementAt(gnCount++);
mtreeitem.IsSelected = true;
}
}

The problem was with the "mytreefile" class.
The below class works fine. The way the "IsSelected" implementation was done made the difference. Posting the code for reference.
class mytreefile : INotifyPropertyChanged
{
private string _name { get; set; }
public ObservableCollection <mytreefile> children { get; set; }
private bool _isSelected;
public bool IsSelected
{
get { return _isSelected; }
set
{
if (value != this._isSelected)
{
this._isSelected = value;
NotifyPropertyChanged("IsSelected");
}
}
}
public mytreefile(string value)
{
_name = value;
children = new ObservableCollection<mytreefile>();
}
void NotifyPropertyChanged(string info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
public event PropertyChangedEventHandler PropertyChanged;
}

WPF MVVM view not updated when viewmodels properties are

Context :
I have a treeview with a separate details view injecting by PRISM library when I click on one of my treeviewitem (and I can update all properties of my item with it). All my items have a Enabled property.
Problem :
When I update programmatically my viewmodels property, my object is updated. If I click on an other treeviewitem and come back to the first one, I see the property was updated.
All the updates are good when I enable/disable the item using my details view (the foreground is going grey and the property is change)
But in my case, when I try to update it by a command triggered by a contextMenu it doesn't trigger the view and all the updates... but my viewmodel property is updated...
What am I going wrong ?
I am using ObservableCollection in my treeview, maybe I need to change the type of my collection ?
I have my BaseViewModel who implements NotifyPropertyChanged
public abstract class NotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(Expression<Func<object>> propertyExpression)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(GetPropertyName(propertyExpression)));
}
private string GetPropertyName(Expression<Func<object>> propertyExpression)
{
var unaryExpression = propertyExpression.Body as UnaryExpression;
var memberExpression = unaryExpression == null ? (MemberExpression)propertyExpression.Body : (MemberExpression)unaryExpression.Operand;
var propertyName = memberExpression.Member.Name;
return propertyName;
}
}
So I call the property change method, but Why my view is not updating then ?
[DefaultValue(true)]
[JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
public bool Enabled
{
get
{
return Model.Enabled;
}
set
{
if (value != Model.Enabled)
{
Model.Enabled = value;
OnPropertyChanged(() => Model.Enabled);
}
}
}
Here is the code of my view (for the command)
<MenuItem Header="Enable/Disable this equipment" Command="{Binding PlacementTarget.Tag.DataContext.ToogleEquipmentCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ContextMenu}}"
CommandParameter="{Binding}" InputGestureText="CTRL+D"/>
And here is the code of my view (Hierarchical data template from my treeview)
<!-- ModuleItems > IP / Name -->
<HierarchicalDataTemplate DataType="{x:Type siemens:ModuleItemSiemensViewModel}" >
<StackPanel Orientation="Horizontal">
<TextBlock Name="ItemIp"
Text="{Binding Path=Ip}" ContextMenu="{StaticResource ContextMenuEquipment}" Tag="{Binding RelativeSource={RelativeSource AncestorType=UserControl}}">
<TextBlock.Style>
<Style TargetType="TextBlock">
<Style.Triggers>
<DataTrigger Binding="{Binding Enabled}" Value="False">
<Setter Property="Background" Value="LightGray"/>
<Setter Property="Foreground" Value="Black"/>
</DataTrigger>
<DataTrigger Binding="{Binding Enabled}" Value="True">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Foreground" Value="Red"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
<TextBlock Text=" / " ContextMenu="{StaticResource ContextMenuEquipment}" Tag="{Binding RelativeSource={RelativeSource AncestorType=UserControl}}">
<TextBlock.Style>
<Style TargetType="TextBlock">
<Style.Triggers>
<DataTrigger Binding="{Binding Enabled}" Value="False">
<Setter Property="Background" Value="LightGray"/>
</DataTrigger>
<DataTrigger Binding="{Binding Enabled}" Value="True">
<Setter Property="Background" Value="Transparent"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
<TextBlock Name="ItemName" ContextMenu="{StaticResource ContextMenuEquipment}" Tag="{Binding RelativeSource={RelativeSource AncestorType=UserControl}}"
Text="{Binding Path=Name}">
<TextBlock.Style>
<Style TargetType="TextBlock">
<Style.Triggers>
<DataTrigger Binding="{Binding Enabled}" Value="False">
<Setter Property="Background" Value="LightGray"/>
<Setter Property="Foreground" Value="Black"/>
</DataTrigger>
<DataTrigger Binding="{Binding Enabled}" Value="True">
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Foreground" Value="Blue"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</StackPanel>
</HierarchicalDataTemplate>
EDIT :
Here is the code from my viewmodel and models :
My real problem is when I update an Item (with my property enabled) it update the item, but my list (ModuleItems) is not updated, what I need to do to correctly implement MVVM and to make my fields automatically updated ?
public class ModuleParamSiemensViewModel : ModuleParamBaseViewModel
{
#region Attributes
private ObservableCollection<ModuleItemSiemensViewModel> _moduleItems;
private ModuleParamSiemens _model;
private string _moduleType;
#endregion
#region Constructor
public ModuleParamSiemensViewModel(ModuleParamSiemens moduleParam) : base(moduleParam)
{
this.Model = moduleParam;
this.ModuleType = "Siemens";
ModuleItems = new ObservableCollection<ModuleItemSiemensViewModel>();
Initialize();
}
#endregion
#region Properties
public new ModuleParamSiemens Model
{
get
{
return _model;
}
set
{
if (value != _model)
{
_model = value;
OnPropertyChanged(() => Model);
}
}
}
public new ObservableCollection<ModuleItemSiemensViewModel> ModuleItems
{
get
{
return _moduleItems;
}
set
{
this._moduleItems = value;
OnPropertyChanged(() => ModuleItems);
}
}
public override string ModuleType
{
get
{
return _moduleType;
}
set
{
this._moduleType = value;
OnPropertyChanged(() => ModuleType);
}
}
#endregion
#region Public Methods
public void Initialize()
{
foreach (ModuleItemSiemens item in this.Model.ModuleItems)
{
Add(new ModuleItemSiemensViewModel(item));
}
}
public void Add(ModuleItemSiemensViewModel item)
{
ModuleItems.Add(item);
}
#endregion
}
Model :
public class ModuleParamSiemens : ModuleParam
{
public new ObservableCollection<ModuleItemSiemens> ModuleItems { get; set; }
public ModuleParamSiemens()
{
ModuleItems = new ObservableCollection<ModuleItemSiemens>();
}
}
EDIT 2 :
Add ItemSiemensViewModel
public class ItemSiemensViewModel : ItemBaseViewModel
{
#region Attributes
private ItemSiemens _model;
#endregion
#region Constructor
public ItemSiemensViewModel(ItemSiemens item)
{
this.Model = item;
}
#endregion
#region Properties
public new ItemSiemens Model
{
get
{
return _model;
}
set
{
if (value != _model)
{
_model = value;
OnPropertyChanged(() => Model);
}
}
}
public new OPCInfo Opc
{
get
{
return Model.Opc;
}
set
{
if (value != Model.Opc)
{
Model.Opc = value;
OnPropertyChanged(() => Model.Opc);
}
}
}
public ProtocolInfoSiemens Protocol
{
get
{
return Model.Protocol;
}
set
{
if (value != Model.Protocol)
{
Model.Protocol = value;
OnPropertyChanged(() => Model.Protocol);
}
}
}
#endregion
#region Public Methods
#endregion
}
ItemSiemens :
public class ItemSiemens : Item
{
public ProtocolInfoSiemens Protocol { get; set; }
}
ItemBaseViewModel
public abstract class ItemBaseViewModel : BaseViewModel
{
public OPCInfoBaseViewModel Opc { get; set; }
public ItemBaseViewModel()
{
}
}
Item
public abstract class Item
{
public OPCInfo Opc { get; set; }
}

I have found the answer.
My bindings are correct (or at least it works)
The problem is that I used ObservableCollection collection and when an item is update in this collection it's not even fire an event to say that something has changed (it does for adding and removing items)
So I have implemented my own ItemsChangeObservableCollection (you can look this answer : https://stackoverflow.com/a/33866549/8237280)
And now all my problems in all my app are solved !

You are sending INotifyPropertyChanged on your ModuleItemSiemensViewModel for the property Model.Enabled. This does not make much sense, as nobody is listening on the VM (ModuleItemSiemensViewModel) for this change. The INPC interface does not allow such a kind of update. Every control listens on the same object that it's binding a property. That means you can only send PropertyChanged for properties that are in the same class/instance the interface is declared.
You have to move the NotifyPropertyChanged to the "Model" instance and call it there like this:
[DefaultValue(true)]
[JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
public bool Enabled
{
get
{
return Model.Enabled;
}
set
{
if (value != Model.Enabled)
{
Model.Enabled = value;
Model.OnPropertyChanged(() => Enabled);
}
}
}

Custom Datagrid OnKeyDown check IsEnabled Items

I have a data grid with Static Data and two of the items are disabled. The only issue is with Silverlight when using the arrow keys to navigate thru the data grid items the disabled items also get focused on.
I have created a custom data grid class and referenced it in the XAML, and then when using the OnKeyDown event I check for IsEnabled True or False. but so far it is not getting the correct values and I think it is because Where I set the IsEnabled status I am referencing the default Datagrid class?
CustomDataGrid
public class CustomGrid : DataGrid
{
protected override void OnKeyDown(KeyEventArgs e)
{
if(IsEnabled != false)
base.OnKeyDown(e);
}
}
Xaml
<UserControl.Resources>
<Style x:Key="DataGridStyle1" TargetType="local:CustomGrid">
<Setter Property="RowStyle">
<Setter.Value>
<Style TargetType="sdk:DataGridRow">
<Setter Property="IsEnabled" Value="{Binding enabled}"/> //CheckIsEnabled Value
</Style>
</Setter.Value>
</Setter>...
<local:CustomGrid x:Name="McDataGrid" HorizontalAlignment="Left" Height="500" VerticalAlignment="Top" Width="400" Style="{StaticResource DataGridStyle1}"/>
List Data
private List<Model> Data()
{
list.Add(new Model(1, "Test", "1", true));
list.Add(new Model(2, "Ger", "2", true));
list.Add(new Model(3, "dsg", "3", true));
list.Add(new Model(4, "Hd", "4", false));
list.Add(new Model(5, "TeHRFdgst", "5", false));
return list;
}
public class Model : INotifyPropertyChanged
{
public bool _enabled;
public int Id { get; set; }
public string Name { get; set; }
public string Prop { get; set; }
public bool enabled
{
get { return _enabled; }
set
{
_enabled = value;
OnPropertyChanged("enabled");
}
}
public event PropertyChangedEventHandler PropertyChanged;
public Model(int id, string name, string prop, bool isenabled)
{
Id = id;
Name = name;
Prop = prop;
enabled = isenabled;
}
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
When I change this <Style TargetType="sdk:DataGridRow"> part with "local:CustomGrid" my entire grid just go blank not to sure why.
Is there any advice on how to accomplish this or maybe a different method?

Try something like this:
public class CustomGrid : DataGrid
{
private List<Model> models;
public CustomGrid()
{
Loaded += (s,e) => models = ItemsSource as List<Model>;
}
protected override void OnKeyDown(KeyEventArgs e)
{
if (models == null)
return;
Model model = CurrentItem as Model;
if (model == null)
return;
int index = models.IndexOf(model);
switch (e.Key)
{
case Key.Down:
//is the next model disabled?
if (index < models.Count - 1 && !models[index + 1].enabled)
e.Handled = true;
break;
case Key.Up:
if (index > 0 && !models[index - 1].enabled)
e.Handled = true;
break;
}
}
}
XAML:
<UserControl ...>
<UserControl.Resources>
<Style x:Key="DataGridStyle1" TargetType="local:CustomGrid">
<Setter Property="RowStyle">
<Setter.Value>
<Style TargetType="sdk:DataGridRow">
<Setter Property="IsEnabled" Value="{Binding enabled}"/>
</Style>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<Grid x:Name="LayoutRoot" Background="White">
<local:CustomGrid x:Name="McDataGrid" Style="{StaticResource DataGridStyle1}" />
</Grid>
</UserControl>

How to make "CanSave" property to Enable/disable binded SaveButton to RelayCommand?

I working on WPF application using MVVM pattern.
the question is :
How to Check wether the Textboxes content are valid or not and by the way make a Save Button Disable until all textboxes fill by valid data.
I googled more and more but in all scenario the answer was implementing IDataerrorInfo on the model but i using entity frameworks entity as model so can not do the implementation.
please give me some advice or links .
thanks in advance.
Below my project description:
the XAML:
<TextBox Name="txtName" Height="23" HorizontalAlignment="Left" Margin="56,42,0,0" VerticalAlignment="Top" Width="120" >
<TextBox.Style>
<Style TargetType="TextBox">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors).CurrentItem.ErrorContent}" />
</Trigger>
</Style.Triggers>
</Style>
</TextBox.Style>
<Binding Path="CurrentItem.Name" UpdateSourceTrigger="PropertyChanged">
<Binding.ValidationRules>
<vm:NotNullValidationRule ValidatesOnTargetUpdated="True"/>
</Binding.ValidationRules>
</Binding>
</TextBox>
and the PersonViweModel.cs
public class PersonViewModel : WorkspaceViewModel
{
SDPS.Business.Base.BaseBusiness<Person> bz = new Business.Base.BaseBusiness<Person>();
#region Constructor
public PersonViewModel(string displayTitle)
{
Items = bz.GetAll();
DisplayName = displayTitle;
NewCommand = new RelayCommand(p => NewItem());
SaveCommand = new RelayCommand(p => SaveItem());
UpdateCommand = new RelayCommand(p => UpdateItem(), p => CanUpdateOrDelete);
DeleteCommand = new RelayCommand(p => DeleteItem(), p => CanUpdateOrDelete);
}
#endregion
#region Methods
private void NewItem()
{
CurrentItem = new Person();
}
private void SaveItem()
{
bz.Add(CurrentItem);
Items.Add(CurrentItem);
}
private void DeleteItem()
{
bz.Delete(CurrentItem);
Items.Remove(CurrentItem);
OnPropertyChanged("Items");
OnPropertyChanged("CurrentItem");
}
public void UpdateItem()
{
bz.Update(CurrentItem);
OnPropertyChanged("Items");
}
#endregion
#region Properties
public Person CurrentItem
{
get { return _CurrentItem; }
set
{
_CurrentItem = value;
OnPropertyChanged("CurrentItem");
}
}
public ObservableCollection<Person> Items
{
get { return _items; }
set
{
_items = value;
OnPropertyChanged("Items");
}
}
public bool CanUpdateOrDelete { get { return CurrentItem != null; } }
#endregion
#region Variables
private ObservableCollection<Person> _items;
private Person _CurrentItem;
#endregion
}
and the ValidationRule Class as below:
public class NotNullValidationRule : ValidationRule
{
public virtual bool HasError
{
get
{
return null;
}
}
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
var result = new ValidationResult(true, null);
if(value!=null)
if (string.IsNullOrWhiteSpace( value.ToString()) )
{
result = new ValidationResult(false, "null string not allowed");
}
return result;
}
}

WPF Menu Binding losing style only in the first level

Please let me know if I am doing something wrong in my code. I am trying to bind a WPF menu to a "MenuViewModel". The binding works as I expect in a non styled Window.
I am using MahApps.Metro for styling purposes only and this is how it looks after binding.
Here's the link to the source code http://sdrv.ms/W5uJpY
ViewModel:
public class Menu : INotifyPropertyChanged
{
public Menu()
{
IsEnabled = true;
Children = new List<Menu>();
}
#region [ Menu Properties ]
private bool _isEnabled;
private string _menuText;
private ICommand _command;
private IList<Menu> _children;
public string MenuText
{
get { return _menuText; }
set
{
_menuText = value;
RaisePropertyChanged("MenuText");
}
}
public bool IsEnabled
{
get { return _isEnabled; }
set
{
_isEnabled = value;
RaisePropertyChanged("IsEnabled");
}
}
public ICommand Command
{
get { return _command; }
set
{
_command = value;
RaisePropertyChanged("Command");
}
}
public IList<Menu> Children
{
get { return _children; }
set
{
_children = value;
}
}
#endregion
#region [INotifyPropertyChanged]
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void RaisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
XAML:
<Menu Grid.Row ="0" IsMainMenu="True" x:Name="mainMenu" VerticalAlignment="Top" ItemsSource="{Binding Children}">
<Menu.ItemContainerStyle>
<Style TargetType="{x:Type MenuItem}" BasedOn="{StaticResource {x:Type MenuItem}}">
<!--Or can be the line below, both yield the same result-->
<!--<Style TargetType="{x:Type MenuItem}" BasedOn="{StaticResource MetroMenuItem}">-->
<!--NOTICE THAT SUB MENU's of OPEN work fine-->
<Setter Property="Header" Value="{Binding Path=MenuText}"/>
<Setter Property="Command" Value="{Binding Path=Command}"/>
<Setter Property="ItemsSource" Value="{Binding Path=Children}"/>
</Style>
</Menu.ItemContainerStyle>
</Menu>

I think I found an answer here
http://karlshifflett.wordpress.com/2008/02/03/wpf-sample-series-databound-hierarchicaldatatemplate-menu-sample/
It does the binding correctly - along with maintaining Separators.