I have a customer usercontrol that is a labeled TextBox (Border wrapped about a Label and a TextBox with the TextBox overlapping the label). I am finding few (working) examples on how to get the TextChanged function to work when called from my UserControl.
Just the textbox snippet:
<TextBox
FontSize="{Binding Path=DefaultFontSize}"
Style="{StaticResource WatermarkTextBox}"
Padding="{Binding Path=TextPadding}"
Tag="{Binding Path=TextValue}"
/>
I have tried using RoutedEventHandler like I did with my button's Click event, but it didn't work. How do I get it so when let's say I use on the window it is required:
<MyControl:LabeledTextBox
TextBoxChange="Some_Event"
TextValue="{Binding SomethingOrOther}"
/>
that it will fire off correctly and do the needed function
This question's really unclear. Do you want your user control to support a TextChanged event that gets raised when the text in the TextBox changes? If so, you need to implement it in the code-behind.
First, declare the event:
public event TextChangedEventHandler TextChanged;
Then, add an event handler to the TextBox:
<TextBox TextChanged="TextBox_TextChanged" ... />
and in the code-behind:
private void TextBox_TextChanged(object sender, TextChangedEventArgs args)
{
TextChangedEventHandler h = TextChanged;
if (h != null)
{
h(this, args);
}
}
If you are using MVVM (Or if your TextValue binding is binding to something you can get to and edit) you can put the logic you want executed in the setter.
So, lets say you are binding to a property MyTextBoxValue. Set the binding mode to two way in the XAML, and in the setter put the logic or call to another method.
If you want the code to fire every time you type, set UpdateSourceTrigger=PropertyChanged in XAML, if you want the code to fire only when text entry is "done" set UpdateSourceTrigger=LostFocus.
Related
I have an ICollectionView, called RepozitorijumWrapper which should display my entities based on six fields. The fields are two TextBox and four DateTimePicker elements. Basically, every time any of those elements change (even by a number/letter) I want the list to update.
My DateTimePicker and TextBox elements are bound to DateTime and string properties, that have the RepozitorijumWrapper.Refresh() code in their setter. When I tested my application, the filter did work, but only once you left the field. After that I tried calling the Refresh() method from the controller, or rather using the TextChanged event for the TextBox elements, and the ValueChanged for the DateTimePickers. This changed nothing. The filter does work, but it isn't refreshed the way I'd like it to refresh.
Since my code is pretty much six copies of the same thing, with changed names and types, I'll only paste one instance of each relevant part of code.
Here's the property:
public string SifraTima
{
get {return sifraTima;}
set
{
if(!sifraTima.Equals(value))
{
sifraTima = value;
RepozitorijumWrapper.Refresh();
}
}
}
Here's the XAML for that property:
<TextBox x:Name="txtSifraTima" Grid.Column="1" Grid.Row="2" Margin="3,3,30,3" Text="{Binding Path=SifraTima}" TextChanged="txtSifraTima_TextChanged" />
Here's the event handler:
private void txtSifraTima_TextChanged(object sender, TextChangedEventArgs e)
{
presenter.RepozitorijumWrapper.Refresh();
}
Here's my ICollectionView, created in the constructor of my presenter class:
RepozitorijumWrapper = CollectionViewSource.GetDefaultView(rezervacije.Kolekcija);
RepozitorijumWrapper.Filter = itm =>
((Rezervacija)itm).SifraTerena.Contains(SifraTerena) &&
((Rezervacija)itm).SifraTima.Contains(SifraTima) &&
((Rezervacija)itm).VremeZauzimanja <= VremeZauzimanjaDo &&
((Rezervacija)itm).VremeZauzimanja >= VremeZauzimanjaOd &&
((Rezervacija)itm).VremeOslobadjanja <= VremeOslobadjanjaDo &&
((Rezervacija)itm).VremeOslobadjanja >= VremeOslobadjanjaOd;
Your binding on the Text property of the TextBox is set to only update the property after the focus is lost by default. To change that behavior, you can specify a value for UpdateSourceTrigger like so:
Text="{Binding Path=SifraTima, UpdateSourceTrigger=PropertyChanged}"
MSDN has more information on UpdateSourceTrigger
I am writing a data entry application and am having problems dealing with add vs edit vs view 'modes' of the app.
The scenario: From a window, the user selects items in two combo boxes and then clicks a button. If the combo box selections don't match an existing record, the form should open with a new record ready to have values inserted. If the selections DO match an existing record, this record should be opened with all the textboxes in the form in 'Readonly' mode. Should the user wish to modify the existing data, they click the form's Edit button which sets the textboxes as 'Editable'.
I'm new to wpf, but in my vba apps, I'd normally have a DataMode property and a ToggleControls method which would loop through the TabControl's TabItems and then loop through the TabItems' controls, setting the IsReadOnly property of any TextBox controls found based on the 'DataMode' property. However, I have doubts about whether this is the path to follow in wpf.
So, my question is, do i use the approach above? If so, how do I access the controls in a TabItem. This doesn't work: foreach (Control ctrl in MyTabCtrl) { //if Textbox do stuff }.
If this isn't the way to do it, can someone show me the way? I'm guessing it's either a template / style issue or something to do with setting the data as readonly somehow, and then binding the TextBox's IsReadOnly property to the state of the data. Edit: Oh, or that ViewStateManager thing. All of which i know little about.
An easy approach would be
In Code behind declare a DependencyProperty named IsReadOnly
public static readonly DependencyProperty IsReadOnlyProperty = DependencyProperty.Register(
"IsReadOnly",
typeof (bool),
typeof (MainWindow)
);
public bool IsReadOnly
{
get { return (bool) GetValue(IsReadOnlyProperty); }
set { SetValue(IsReadOnlyProperty, value); }
}
Implement the Buttons Click event, so that IsReadOnly gets false on Click
private void Button_Click(object sender, RoutedEventArgs e)
{
IsReadOnly = false;
}
Bind the TextBoxes to the IsReadonly property using DataBinding
<TextBox IsReadOnly="{Binding Path=IsReadOnly, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}, Mode=OneWay}" />
This binding assumes that your code behind is not your DataContext and you therefore have to bind relatively to the Window/ UserControl which the CodeBehind is applied to.
This way the TextBoxes listen to changes on this property. When it switches, they change their ReadOnly state automatically.
You can use DataContext :
Bind the datacontext of your tabControl to your record (with the button event click write
this.Canvas.DataContext = _yourRecord for sample)
public void bntEvent_Click(object sender, EventArgs e)
{
// Do matching and put the result in result field
MyTabCtrl.DataContext = false;
}
Bind IsReadOnly/IsEnable property of your textboxs on your datacontext and use a converter to return true/false value
<TextBox IsReadOnly="{Binding .}" />
See http://msdn.microsoft.com/en-us/library/system.windows.data.ivalueconverter.aspx for more informations about Converters.
I hope I help you and you understand my bad English.
Good bye
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 cannot get a two-way bind in WPF to work.
I have a string property in my app's main window that is bound to a TextBox (I set the mode to "TwoWay").
The only time that the value of the TextBox will update is when the window initializes.
When I type into the TextBox, the underlying string properties value does not change.
When the string property's value is changed by an external source (an event on Click, for example, that just resets the TextBox's value), the change doesn't propagate up to the TextBox.
What are the steps that I must implement to get two-way binding to work properly in even this almost trivial example?
Most probably you're trying to bind to a .net CLR property instead of a WPF dependencyProperty (which provides Change Notification in addition to some other things).
For normal CLR property, you'd need to implement INotifyPropertyChanged and force update on the textbox in the event handler for PropertyChanged.
So make your object with the property implement this interface, raise the event in the property setter. (So now we have property change notification)
Make sure the object is set as the DataContext property of the UI element/control
This threw me off too when I started learning about WPF data binding.
Update: Well OP, it would have been a waste of time if i was barking up the wrong tree.. anyways now since you had to dig a bit.. you'll remember it for a long time. Here's the code snippet to round off this answer. Also found that updating the textbox happens automatically as soon as I tab-out.. You only need to manually subscribe to the event and update the UI if your datacontext object is not the one implementing INotifyPropertyChanged.
MyWindow.xaml
<Window x:Class="DataBinding.MyWindow" ...
Title="MyWindow" Height="300" Width="300">
<StackPanel x:Name="TopLevelContainer">
<TextBox x:Name="txtValue" Background="AliceBlue" Text="{Binding Path=MyDotNetProperty}" />
<TextBlock TextWrapping="Wrap">We're twin blue boxes bound to the same property.</TextBlock>
<TextBox x:Name="txtValue2" Background="AliceBlue" Text="{Binding Path=MyDotNetProperty}" />
</StackPanel>
</Window>
MyWindow.xaml.cs
public partial class MyWindow : Window, INotifyPropertyChanged
{
public MyWindow()
{
InitializeComponent();
this.MyDotNetProperty = "Go ahead. Change my value.";
TopLevelContainer.DataContext = this;
}
private string m_sValue;
public string MyDotNetProperty
{
get { return m_sValue; }
set
{
m_sValue = value;
if (null != this.PropertyChanged)
{
PropertyChanged(this, new PropertyChangedEventArgs("MyDotNetProperty"));
}
}
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
#endregion
}
I feel the need to add some precision:
"Two ways" data binding is more than "One way" data binding.
"One way" data binding is a binding from a source to a dependency property. The source must implement INotifyPropertyChanged, in order to get change propagation from source to target.
To get the " 2 way" , so to get a propagation from Target to Source, it depends on the binding mode which you set on the Binding . If you don't set any BindingMode for your binding, the default Binding mode will be used, and this default mode is a characteristics for your target Dependency Property.
Example:
A Textbox bound to a string property, called "MyTextProperty".
In the code, you bind Textbox.Text DependencyProperty to "MyTextProperty" on object "MyObject"
--> "one way" binding : the setter of "My TextProperty" must raise an event Property Changed,and "MyObject" must implement INotifyPropertyChanged.
--> "2 ways data binding": in addition to what is needed for "One way", bindingMode must be set to "2 ways". In this special case, the Text DependencyProperty for Textbox does have "2 ways" as default mode, so there is nothing else to do !
We might need to see the code. Does your string property raise a PropertyChanged event? Or (even better) is it implemented as a DependencyProperty? If not, the bound TextBox won't know when the value changes.
As for typing into the TextBox and not seeing the property's value change, that may be because your TextBox isn't losing focus. By default, bound TextBoxes don't write their values back to the source property until focus leaves the control. Try tabbing out of it and seeing if the property value changes.
Make sure that the binding specifies two way and when the property has a change, it is immediately transmitted to the holding property.
<TextBox Text="{Binding TextBuffer,
UpdateSourceTrigger=PropertyChanged,
Mode=TwoWay}"/>
The above assures that the TextBox input control Text property binds to, then sends the changes back to the string property named TextBuffer in an immediate, PropertyChanged, and TwoWay fashion.
In my WPF application, I have a number of databound TextBoxes. The UpdateSourceTrigger for these bindings is LostFocus. The object is saved using the File menu. The problem I have is that it is possible to enter a new value into a TextBox, select Save from the File menu, and never persist the new value (the one visible in the TextBox) because accessing the menu does not remove focus from the TextBox. How can I fix this? Is there some way to force all the controls in a page to databind?
#palehorse: Good point. Unfortunately, I need to use LostFocus as my UpdateSourceTrigger in order to support the type of validation I want.
#dmo: I had thought of that. It seems, however, like a really inelegant solution for a relatively simple problem. Also, it requires that there be some control on the page which is is always visible to receive the focus. My application is tabbed, however, so no such control readily presents itself.
#Nidonocu: The fact that using the menu did not move focus from the TextBox confused me as well. That is, however, the behavior I am seeing. The following simple example demonstrates my problem:
<Window x:Class="WpfApplication2.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Window.Resources>
<ObjectDataProvider x:Key="MyItemProvider" />
</Window.Resources>
<DockPanel LastChildFill="True">
<Menu DockPanel.Dock="Top">
<MenuItem Header="File">
<MenuItem Header="Save" Click="MenuItem_Click" />
</MenuItem>
</Menu>
<StackPanel DataContext="{Binding Source={StaticResource MyItemProvider}}">
<Label Content="Enter some text and then File > Save:" />
<TextBox Text="{Binding ValueA}" />
<TextBox Text="{Binding ValueB}" />
</StackPanel>
</DockPanel>
</Window>
using System;
using System.Text;
using System.Windows;
using System.Windows.Data;
namespace WpfApplication2
{
public partial class Window1 : Window
{
public MyItem Item
{
get { return (FindResource("MyItemProvider") as ObjectDataProvider).ObjectInstance as MyItem; }
set { (FindResource("MyItemProvider") as ObjectDataProvider).ObjectInstance = value; }
}
public Window1()
{
InitializeComponent();
Item = new MyItem();
}
private void MenuItem_Click(object sender, RoutedEventArgs e)
{
MessageBox.Show(string.Format("At the time of saving, the values in the TextBoxes are:\n'{0}'\nand\n'{1}'", Item.ValueA, Item.ValueB));
}
}
public class MyItem
{
public string ValueA { get; set; }
public string ValueB { get; set; }
}
}
I found that removing the menu items that are scope depended from the FocusScope of the menu causes the textbox to lose focus correctly. I wouldn't think this applies to ALL items in Menu, but certainly for a save or validate action.
<Menu FocusManager.IsFocusScope="False" >
Assuming that there is more than one control in the tab sequence, the following solution appears to be complete and general (just cut-and-paste)...
Control currentControl = System.Windows.Input.Keyboard.FocusedElement as Control;
if (currentControl != null)
{
// Force focus away from the current control to update its binding source.
currentControl.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
currentControl.Focus();
}
This is a UGLY hack but should also work
TextBox focusedTextBox = Keyboard.FocusedElement as TextBox;
if (focusedTextBox != null)
{
focusedTextBox.GetBindingExpression(TextBox.TextProperty).UpdateSource();
}
This code checks if a TextBox has focus... If 1 is found... update the binding source!
Suppose you have a TextBox in a window, and a ToolBar with a Save button in it. Assume the TextBox’s Text property is bound to a property on a business object, and the binding’s UpdateSourceTrigger property is set to the default value of LostFocus, meaning that the bound value is pushed back to the business object property when the TextBox loses input focus. Also, assume that the ToolBar’s Save button has its Command property set to ApplicationCommands.Save command.
In that situation, if you edit the TextBox and click the Save button with the mouse, there is a problem. When clicking on a Button in a ToolBar, the TextBox does not lose focus. Since the TextBox’s LostFocus event does not fire, the Text property binding does not update the source property of the business object.
Obviously you should not validate and save an object if the most recently edited value in the UI has not yet been pushed into the object. This is the exact problem Karl had worked around, by writing code in his window that manually looked for a TextBox with focus and updated the source of the data binding. His solution worked fine, but it got me thinking about a generic solution that would also be useful outside of this particular scenario. Enter CommandGroup…
Taken from Josh Smith’s CodeProject article about CommandGroup
Simple solution is update the Xaml code as shown below
<StackPanel DataContext="{Binding Source={StaticResource MyItemProvider}}">
<Label Content="Enter some text and then File > Save:" />
<TextBox Text="{Binding ValueA, UpdateSourceTrigger=PropertyChanged}" />
<TextBox Text="{Binding ValueB, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
I've run into this issue and the best solution I've found was to change the focusable value of the button (or any other component such as MenuItem) to true:
<Button Focusable="True" Command="{Binding CustomSaveCommand}"/>
The reason it works, is because it forces the button to get focused before it invokes the command and therefore makes the TextBox or any other UIElement for that matter to loose their focus and raise lost focus event which invokes the binding to be changed.
In case you are using bounded command (as I was pointing to in my example), John Smith's great solution won't fit very well since you can't bind StaticExtension into bounded property (nor DP).
Have you tried setting the UpdateSourceTrigger to PropertyChanged? Alternatively, you could call the UpdateSOurce() method, but that seems like a bit overkill and defeats the purpose of TwoWay databinding.
Could you set the focus somewhere else just before saving?
You can do this by calling focus() on a UI element.
You could focus on whatever element invokes the "save". If your trigger is LostFocus then you have to move the focus somewhere. Save has the advantage that it isn't modified and would make sense to the user.
Since I noticed this issue is still a pain in the ass to solve on a very generic way, I tried various solutions.
Eventually one that worked out for me:
Whenever the need is there that UI changes must be validated and updated to its sources (Check for changes upon closeing a window, performing Save operations, ...), I call a validation function which does various things:
- make sure a focused element (like textbox, combobox, ...) loses its focus which will trigger default updatesource behavior
- validate any controls within the tree of the DependencyObject which is given to the validation function
- set focus back to the original focused element
The function itself returns true if everything is in order (validation is succesful) -> your original action (closeing with optional asking confirmation, saveing, ...) can continue. Otherwise the function will return false and your action cannot continue because there are validation errors on one or more elements (with the help of a generic ErrorTemplate on the elements).
The code (validation functionality is based on the article Detecting WPF Validation Errors):
public static class Validator
{
private static Dictionary<String, List<DependencyProperty>> gdicCachedDependencyProperties = new Dictionary<String, List<DependencyProperty>>();
public static Boolean IsValid(DependencyObject Parent)
{
// Move focus and reset it to update bindings which or otherwise not processed until losefocus
IInputElement lfocusedElement = Keyboard.FocusedElement;
if (lfocusedElement != null && lfocusedElement is UIElement)
{
// Move to previous AND to next InputElement (if your next InputElement is a menu, focus will not be lost -> therefor move in both directions)
(lfocusedElement as UIElement).MoveFocus(new TraversalRequest(FocusNavigationDirection.Previous));
(lfocusedElement as UIElement).MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
Keyboard.ClearFocus();
}
if (Parent as UIElement == null || (Parent as UIElement).Visibility != Visibility.Visible)
return true;
// Validate all the bindings on the parent
Boolean lblnIsValid = true;
foreach (DependencyProperty aDependencyProperty in GetAllDependencyProperties(Parent))
{
if (BindingOperations.IsDataBound(Parent, aDependencyProperty))
{
// Get the binding expression base. This way all kinds of bindings (MultiBinding, PropertyBinding, ...) can be updated
BindingExpressionBase lbindingExpressionBase = BindingOperations.GetBindingExpressionBase(Parent, aDependencyProperty);
if (lbindingExpressionBase != null)
{
lbindingExpressionBase.ValidateWithoutUpdate();
if (lbindingExpressionBase.HasError)
lblnIsValid = false;
}
}
}
if (Parent is Visual || Parent is Visual3D)
{
// Fetch the visual children (in case of templated content, the LogicalTreeHelper will return no childs)
Int32 lintVisualChildCount = VisualTreeHelper.GetChildrenCount(Parent);
for (Int32 lintVisualChildIndex = 0; lintVisualChildIndex < lintVisualChildCount; lintVisualChildIndex++)
if (!IsValid(VisualTreeHelper.GetChild(Parent, lintVisualChildIndex)))
lblnIsValid = false;
}
if (lfocusedElement != null)
lfocusedElement.Focus();
return lblnIsValid;
}
public static List<DependencyProperty> GetAllDependencyProperties(DependencyObject DependencyObject)
{
Type ltype = DependencyObject.GetType();
if (gdicCachedDependencyProperties.ContainsKey(ltype.FullName))
return gdicCachedDependencyProperties[ltype.FullName];
List<DependencyProperty> llstDependencyProperties = new List<DependencyProperty>();
List<FieldInfo> llstFieldInfos = ltype.GetFields(BindingFlags.Public | BindingFlags.FlattenHierarchy | BindingFlags.Instance | BindingFlags.Static).Where(Field => Field.FieldType == typeof(DependencyProperty)).ToList();
foreach (FieldInfo aFieldInfo in llstFieldInfos)
llstDependencyProperties.Add(aFieldInfo.GetValue(null) as DependencyProperty);
gdicCachedDependencyProperties.Add(ltype.FullName, llstDependencyProperties);
return llstDependencyProperties;
}
}
The easiest way is to set the focus somewhere.
You can set the focus back immediately, but setting the focus anywhere will trigger the LostFocus-Event on any type of control and make it update its stuff:
IInputElement x = System.Windows.Input.Keyboard.FocusedElement;
DummyField.Focus();
x.Focus();
Another way would be to get the focused element, get the binding element from the focused element, and trigger the update manually. An example for TextBox and ComboBox (you would need to add any control type you need to support):
TextBox t = Keyboard.FocusedElement as TextBox;
if ((t != null) && (t.GetBindingExpression(TextBox.TextProperty) != null))
t.GetBindingExpression(TextBox.TextProperty).UpdateSource();
ComboBox c = Keyboard.FocusedElement as ComboBox;
if ((c != null) && (c.GetBindingExpression(ComboBox.TextProperty) != null))
c.GetBindingExpression(ComboBox.TextProperty).UpdateSource();
What do you think about this? I believe I've figured out a way to make it a bit more generic using reflection. I really didn't like the idea of maintaining a list like some of the other examples.
var currentControl = System.Windows.Input.Keyboard.FocusedElement;
if (currentControl != null)
{
Type type = currentControl.GetType();
if (type.GetMethod("MoveFocus") != null && type.GetMethod("Focus") != null)
{
try
{
type.GetMethod("MoveFocus").Invoke(currentControl, new object[] { new TraversalRequest(FocusNavigationDirection.Next) });
type.GetMethod("Focus").Invoke(currentControl, null);
}
catch (Exception ex)
{
throw new Exception("Unable to handle unknown type: " + type.Name, ex);
}
}
}
See any problems with that?
Using BindingGroup will help to understand and mitigate this kind of problem.
Sometimes we consider to apply MVVM model against WPF data bindings.
For example, we consider about mail's subject property:
<TextBox x:Name="SubjectTextBox" Text="{Binding Subject}" />
TextBox SubjectTextBox is on side of View.
The bound property like ViewModel.Subject will belong to ViewModel.
The problem is that changes remain to View in this case.
When we close the WPF window, WPF TextBox won't loose focus on window close.
It means data binding won't perform writing back, and then changes are lost silently.
Introducing of BindingGroup helps to control whether we should apply changes: from View to ViewModel.
BindingGroup.CommitEdit(); will ensure apply changes of direction View → ViewModel
BindingGroup.CancelEdit(); will ensure to discard changes on View.
If you don't call neither, changes are lost silently!
In the following sample, we attach RibbonWindow_Closing event handler so that we can deal with this case of problem.
XAML:
<R:RibbonWindow Closing="RibbonWindow_Closing" ...>
<FrameworkElement.BindingGroup>
<BindingGroup />
</FrameworkElement.BindingGroup>
...
</R:RibbonWindow>
C#
private void RibbonWindow_Closing(object sender, CancelEventArgs e) {
e.Cancel = !NeedSave();
}
bool NeedSave() {
if (!BindingGroup.CommitEdit()) {
// There may be validation error.
return false; // changes this to true to allow closing.
}
// Insert your business code to check modifications.
// return true; if Saved/DontSave/NotChanged
// return false; if Cancel
}
It should work.