I have a static collection:
<CollectionViewSource Source="{Binding Source={x:Static Application.Current}, Path=MarketDataListeners}" x:Key="ficServerMarketDataView"></CollectionViewSource>
which is a collection of type MarketDataListener.
I have a ListView which is bound to this collection and a ContentControl which is bound to the selected item of this ListView. In the ContentControl I have a button that launches a child window (in code behind).
What Im doing is keeping track of the selected item in the main window like this:
private void ListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
_selectedItem = ((sender as ListView).SelectedValue as MarketDataContainer);
}
and then when the button in the control control is clicked i execute:
private void ShowComponentsButton_Click(object sender, RoutedEventArgs e)
{
var detailsWindow = new ComponentWindow(_selectedItem);
var button = sender as Button;
if (button == null) return;
detailsWindow.Show();
}
This is the binding of the ContentControl:
<ContentControl Name="Detail" Content="{Binding Source={StaticResource ficServerMarketDataView}}"
ContentTemplate="{StaticResource detailsFicTemplate}" VerticalAlignment="Stretch" Foreground="Black" DockPanel.Dock="Bottom" />
Is it possible to remove the code tracking the selected item just launch the child window without a parameter? The child window's Title should be a property 'Name' on the currently selected MarketDataListener. Ideally the child window would not update when the selected item changes.
Is it possible to remove the code tracking the selected item just launch the child window without a parameter?
I would strongly recommend you to show the details in the same window,
from user experience point of view it would be preferable.
you can use a page or contentControl to show the detailsWindow data.
in that case it would be easy to achieve what you are looking for, all you would have to do is bind the ContentControl.dataContext to listviewSelected item.
otherwise if you just have to by design create a new Window you could create a singelton ViewModel which would be bound to the ListViewSelected Item and each time you will open the DetailsWindow you would access this data.
Related
I have a value that can change that doesn't raise a change event and the menu item bound to the value doesn't correctly reflect the state when the menu item is opened. I'd like to update this binding when the menu opens. How do I do this?
Can I have a menu item that just polls it's bindings each time the menu is opened? In this case the IsCommEnabled property:
<MenuItem Header="{Binding EnableComm}"
Command="{Binding Root.ToggleCommunications}"
IsChecked="{Binding Authorization.IsCommEnabled, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"/>
--
public bool IsCommEnabled {
get { return _communications.IsCommEnabled; }
}
You can subscribe to the SubmenuOpened event, and manually update the binding:
void MenuItem_SubmenuOpened(object sender, RoutedEventArgs e)
{
((MenuItem)sender).GetBindingExpression(MenuItem.IsCheckedProperty).UpdateTarget();
}
Please note that the above applies to the Parent item being opened, so you may need to wrangle it a bit to ensure that it is the right item that is getting updated. You can use the Items collection on the MenuItem to dig deeper.
You have to raise NotifyPropertyChanged if you want to push the IsCommEnabled back to the bound Dependency Property
I am trying to bind the IsEnabled property of a button to properties of the window's CollectionViewSource. I am doing this to implement First/Previous/Next/Last buttons and want the First and Previous to be disabled when the view is on the first item etc.
I have the collection view source set up, UI controls binding to it correctly, with access to its view in code so the click event handlers work fine in navigating through the view.
<CollectionViewSource x:Key="cvMain" />
The DockPanel is the root element of the window
<DockPanel DataContext="{StaticResource cvMain}">
FoJobs is an observable collection, cvJobs is a CollectionView that I use in the button's click handler
private void Window_Loaded(object sender, RoutedEventArgs e) {
((CollectionViewSource)Resources["cvMain"]).Source = FoJobs;
cvJobs = (CollectionView)((CollectionViewSource)Resources["cvMain"]).View;
}
I have tried this but get a binding error "BindingExpression path error: '' property not found on 'object' ''ListCollectionView'"
<Button Name="cbFirst" Click="cbMove_Click" IsEnabled="{Binding Source={StaticResource cvMain}, Converter={StaticResource CurrPos2BoolConverter}}" />
I am trying to do with a converter first but figure a style with triggers would be more efficient, but cant get access to the collection view. Even though the underlying datacontext is set to a collection view source, the binding is passed to the converter as the view's source (if I dont explicity set the binding's Source, as above), which has no currency properties (CurrentPosition, Count etc).
Any help would be greatly appreciated.
Why don't you use a RoutedCommand for this(even if you don't use MVVM that is)?
say something like:
<Button x:Name="nextButton"
Command="{x:Static local:MainWindow.nextButtonCommand}"
Content="Next Button" />
and in your code-behind:
public static RoutedCommand nextButtonCommand = new RoutedCommand();
public MainWindow() {
InitializeComponent();
CommandBinding customCommandBinding = new CommandBinding(
nextButtonCommand, ExecuteNextButton, CanExecuteNextButton);
nextButton.CommandBindings.Add(customCommandBinding); // You can attach it to a top level element if you wish say the window itself
}
private void CanExecuteNextButton(object sender, CanExecuteRoutedEventArgs e) {
e.CanExecute = /* Set to true or false based on if you want button enabled or not */
}
private void ExecuteNextButton(object sender, ExecutedRoutedEventArgs e) {
/* Move code from your next button click handler in here */
}
You can also apply one of the suggestions from Explicitly raise CanExecuteChanged() to manually re-evaluate Button.isEnabled state.
This way your encapsulating logic relating to the button in one area.
This is a running question that I have updated to hopefully be a little more clear.
In short what I am trying to accomplish is pass a property from a listbox selected item to the viewmodel so that this property can be used within a new query. In the code below the Listbox inherits databinding from the parent object. The listbox contains data templates (user controls) used to render out detailed results.
The issue I am having is that within the user control I have an expander which when clicked calls a command from the ViewModel. From what I can see the Listbox object is loosing it's data context so in order for the command to be called when the expander is expanded I have to explicitly set the datacontext of the expander. Doing this seems to instantiate a new view model which resets my bound property (SelectedItemsID) to null.
Is there a way to pass the selected item from the view to the viewmodel and prevent the value from being reset to null when a button calls a command from within the templated listbox item?
I realize that both Prism and MVVMLite have workarounds for this but I am not familiar with either framework so I don't know the level of complexity in cutting either of these into my project.
Can this be accomplished outside of Prism or MVVMLite?
original post follows:
Within my project I have a listbox usercontrol which contains a custom data template.
<ListBox x:Name="ResultListBox"
HorizontalAlignment="Stretch"
Background="{x:Null}"
BorderThickness="0"
HorizontalContentAlignment="Stretch"
ItemsSource="{Binding SearchResults[0].Results,
Mode=TwoWay}"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
SelectionChanged="ResultListBox_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<dts:TypeTemplateSelector Content="{Binding}" HorizontalContentAlignment="Stretch">
<!-- CFS Template -->
<dts:TypeTemplateSelector.CFSTemplate>
<DataTemplate>
<qr:srchCFS />
</DataTemplate>
</dts:TypeTemplateSelector.CFSTemplate>
<!-- Person Template -->
<dts:TypeTemplateSelector.PersonTemplate>
<DataTemplate>
<qr:srchPerson />
</DataTemplate>
</dts:TypeTemplateSelector.PersonTemplate>
<!-- removed for brevity -->
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
SelectionChanged calls the following method from the code behind
private void ResultListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (((ListBox)sender).SelectedItem != null)
_ViewModel.SelectedItemID = (((ListBox)sender).SelectedItem as QueryResult).ID.ToString();
this.NotifyPropertyChanged(_ViewModel.SelectedItemID);//binds to VM
}
Within the ViewModel I have the following property
public string SelectedItemID
{
get
{
return this._SelectedItemID;
}
set
{
if (this._SelectedItemID == value)
return;
this._SelectedItemID = value;
}
}
the listbox template contains a custom layout with an expander control. The expander control is used to display more details related to the selected item. These details (collection) are created by making a new call to my proxy. To do this with an expander control I used the Expressions InvokeCommandAction
<toolkit:Expander Height="auto"
Margin="0,0,-2,0"
Foreground="#FFFFC21C"
Header="View Details"
IsExpanded="False"
DataContext="{Binding Source={StaticResource SearchViewModelDataSource}}"
Style="{StaticResource DetailExpander}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Expanded">
<i:InvokeCommandAction Command="{Binding GetCfsResultCommand}" />
</i:EventTrigger>
</i:Interaction.Triggers>
Within the ViewModel the delegate command GetCFSResultCommandExecute which is called is fairly straight forward
private void GetCfsResultCommandExecute(object parameter)
{
long IdResult;
if (long.TryParse(SelectedItemID, out IdResult))
{
this.CallForServiceResults = this._DataModel.GetCFSResults(IdResult);}
The issue I am experiencing is when selecting a listbox Item the selectionchanged event fires and the property SelectedItemID is updated with the correct id from the selected item. When I click on the expander the Command is fired but the property SelectedItemID is set to null. I have traced this with Silverlight-Spy and the events are consistent with what you would expect when the expander is clicked the listbox item loses focus, the expander (toggle) gets focus and there is a LeftMouseDownEvent but I cannot see anything happening that explains why the property is being set to null. I added the same code used in the selection changed event to a LostFocus event on the listboxt item and still received the same result.
I'd appreciate any help with understanding why the public property SelectedItemID is being set to null when the expander button which is part of the listbox control is being set to null. And of course I would REALLY appreciate any help in learning how prevent the property from being set to null and retaining the bound ID.
Update
I have attempted to remove the datacontext reference from the Expander as this was suggested to be the issue. From what I have since this is a data template item it "steps" out of the visual tree and looses reference to the datacontext of the control which is inherited from the parent object. If I attempt to set the datacontext in code for the control all bindings to properties are lost.
My next attempt was to set the datacontext for the expander control within the constructor as
private SearchViewModel _ViewModel;
public srchCFS()
{
InitializeComponent();
this.cfsExpander.DataContext = this._ViewModel;
}
This approach does not seem to work as InvokeCommandAction is never fired. This command only seems to trigger if data context is set on the expander.
thanks in advance
With this line you create a new SearchViewModelDataSource using its default constructor.
DataContext="{Binding Source={StaticResource SearchViewModelDataSource}}"
I guess this is why you find null because this is the default value for reference type.
You can resolve the issue by setting DataContext to the same instance used to the main controll (you can do it by code after all components are initialized).
Hope this help!
Edit
I don't think that binding may be lost after setting datacontext from code. I do it every time I need to share something between two or more model.
In relation to the code you've written :
private SearchViewModel _ViewModel;
public srchCFS()
{
InitializeComponent();
this.cfsExpander.DataContext = this._ViewModel;
}
Instead of using this.cfsExpander you can try to use the FindName method. Maybe this will return you the correct instance.
object item = this.FindName("expander_name");
if ((item!=null)&&(item is Expander))
{
Expander exp = item as Expander;
exp.DataContext = this._ViewModel;
}
Try if its work for you.
Of course, this._ViewModel has to expose a property of type ICommand named GetCfsResultCommand but I think this has been already done.
While this was a hacky approach I found an intermediate solution to get the listbox item value to the view model. I ended up using the selection changed event and passing the value directly to a public property wihtin my view model. Not the best approach but it resolved the issue short term
private void ResultListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (((ListBox)sender).SelectedItem != null)
_ViewModel.SelectedItemID = (((ListBox)sender).SelectedItem as QueryResult).ID.ToString();
MySelectedValue = (((ListBox)sender).SelectedItem as QueryResult).ID.ToString();
this.NotifyPropertyChanged(_ViewModel.SelectedItemID);
}
For this to fire I did have to also setup a property changed handler within the view to push the change to the VM. You can disregard the MySelectedValue line as it is secondary code I have in place for testing.
For those intereted the generic property changed handler
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
I have a WPF TreeView with a HierarchicalDataTemplate.
Currently I have to double click an item to expand/collapse it.
I would like to change this behaviour to a single click, without loosing other functionality. So it should expand and collapse on click.
What is the recommended way to do this?
Thanks!
You could use a re-templated checkbox as your node (containing whatever template you are currently using) with its IsChecked property bound to the IsExpanded property of the TreeViewItem.
Here is a template I've just test that seems to do the job:
<HierarchicalDataTemplate ItemsSource="{Binding Items}">
<CheckBox IsChecked="{Binding RelativeSource={RelativeSource AncestorType=TreeViewItem}, Path=IsExpanded}">
<CheckBox.Template>
<ControlTemplate>
<TextBlock Text="{Binding Header}"></TextBlock>
</ControlTemplate>
</CheckBox.Template>
</CheckBox>
</HierarchicalDataTemplate>
Just replace the ControlTemplate contents with whatever you need.
If you are using a standard TreeViewItem, then you can capture the click event:
private void OnTreeViewMouseUp( object sender, MouseButtonEventArgs e )
{
var tv = sender as TreeView;
var item = tv.SelectedItem as TreeViewItem;
if( item != null )
item.IsExpanded = !item.IsExpanded;
e.Handled = true;
}
private void OnTreeViewPreviewMouseDoubleClick( object sender, MouseButtonEventArgs e )
{
e.Handled = true;
}
Most likely in your case, you'll need to do something with your binding and ViewModel. Here's a good article from CodePlex: Simplifying the WPF TreeView by Using the ViewModel Pattern.
Just use selected item changed event and use the following,
private void treeview_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
TreeViewItem item = (TreeViewItem)treeview.SelectedItem;
item.IsExpanded = true;
}
where treeview is the name of your TreeView, you could include an if to close/open based on its current state.
I have very little experience working with WPF to this point, so I am not 100% certain here. However, you might check out the .HitTest method of both the Treeview and TreeView Item (the WPF Treeview is essentially the Windows.Controls.Treeview, yes? Or a derivation thereof?).
THe HIt Test method does not always automatically appear in the Intellisense menu for a standard Windows.Forms.Treeview (I am using VS 2008) until you type most of the method name. But it should be there. You may have to experimnt.
You can use the .HitTest Method to handle the MouseDown event and return a reference to the selected treeview item. You must test for a null return, however, in case the use clicks in an area of the control which contains no Tree Items. Once you have a reference to a specific item, you should be able to set its .expanded property to the inverse of whatever it is currently. again, some experimentation may be necessary here.
As I said, I have not actually used WPF yet, so I could have this Wrong . . .
The answer of Metro Smurf (thanks to which I got where I wanted to be) suggests the right approach . You could simply hook up to the SelectedItemChanged event of the Treeview. Then cast the e.NewValue passed in the eventhandler as TreeViewItem, and access its IsExpanded property to set it to true.
void MyFavoritesTreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
((TreeViewItem)e.NewValue).IsExpanded = true;
}
Then for the final touch, you can also hook up the items in your Treeview by casting them as TreeViewItem as suggested, and then you can hook up to the various manipulation events, like:
var item = tv.SelectedItem as TreeViewItem;
item.Expanded += item_Expanded;
And then do whatever you need to do in the eventhandler
void item_Expanded(object sender, RoutedEventArgs e)
{
// handle your stuff
}
I am implementing a file upload tool using Silverlight. In this I can browse for files and when I select a file then it is bound to a datagrid. In the datagrid I have a template column with a button to delete the particular item from the datagrid and ItemSource of the datagrid which is a List<>.
I have a class UploadedFiles as below.
public class UploadedFiles
{
public FileInfo FileInf{get;set;}
public int UniqueID{get;set;}
public string FileName{get;set;}
public string FileExtension{get;set;}
public long FileSize{get;set;}
}
I am using a datagrid with a templatecolumn like below with ItemSource set as List<UploadedFiles>
<data:DataGridTemplateColumn Width="100">
<data:DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Click="btn_Click" Content="Del" Width="45"/>
</DataTemplate>
</data:DataGridTemplateColumn.CellTemplate>
</data:DataGridTemplateColumn>
and the button click event handler is
private void btn_Click(object sender, System.Windows.RoutedEventArgs e)
{
/* I need to access the particular list item based on the datagrid
row in which the clicked button resides.*/
}
I need to access the particular list item based on the datagrid row in which the clicked button resides and remove the item from the List<UploadedFiles> and rebind the datagrid.
Thanks
Two things to look at here:
Firstly, to get the individual UploadedFiles object, cast the sender to a Button (or FrameworkElement) and access the DataContext property. The DataContext will be the UploadedFiles row (you will need to cast again from object).
Secondly, rather than removing the item from the list and rebinding, have you considered using an ObservableCollection instead? If you use that, removing the row will automatically remove it from the DataGrid without needing you to rebind.
private void btn_Click(object sender, System.Windows.RoutedEventArgs e)
{
var uploadedFiles = (UploadedFiles)((FrameworkElement)sender).DataContext;
//access collection and remove element
}