WPF autocompletebox and the enter key - wpf

Question

I am trying to get the WPF AutoCompleteBox to raise the KeyDown event when I press the enter key. I am using the normal KeyDown hook, which works for everything but the enter key it seems. Does anyone know how I can fix this?

Answer 1

You could inherit the AutoCompleteBox, adding an event for Enter.
public class MyAutoCompleteBox : AutoCompleteBox
{
public override void OnKeyDown(KeyEventArgs e)
{
base.OnKeyDown(e);
if(e.Key == Key.Enter) RaiseEnterKeyDownEvent();
}
public event Action<object> EnterKeyDown;
private void RaiseEnterKeyDownEvent()
{
var handler = EnterKeyDown;
if(handler != null) handler(this);
}
}
In your consuming class, you can subscribe:
public void Subscribe()
{
autoCompleteBox.EnterKeyDown += DoSomethingWhenEnterPressed;
}
public void DoSomethingWhenEnterPressed(object sender)
{
}

Answer 2

Very late answer, but I faced this same problem that brought me to this question and finally solved it using PreviewKeyDown
<wpftoolkit:AutoCompleteBox Name="AutoCompleteBoxCardName"
Populating="LoadAutocomplete"
PreviewKeyDown="AutoCompleteBoxName_PreviewKeyDown"/>
and
private void AutoCompleteBoxName_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Key.Enter)
{
//...
}
}

Answer 3

There is a slightly easier (and in my opinion more MVVM) way:
// This still goes in your code behind (yuck!)
protected override void OnKeyDown(KeyEventArgs e)
{
if (!IsDropDownOpen && SelectedItem != null && (e.Key == Key.Enter || e.Key == Key.Return))
{
// Drop down is closed so the item in the textbox should be submitted with a press of the Enter key
base.OnKeyDown(e); // This has to happen before we mark Handled = false
e.Handled = false; // Set Handled = false so the event bubbles up to your inputbindings
return;
}
// Drop down is open so user must be selecting an AutoComplete list item
base.OnKeyDown(e);
}
This minimizes the blasphemous code-behind and allows your key event to continue to bubble up to something like an input binding:
<UserControl.InputBindings>
<KeyBinding Key="Tab" Command="{Binding NextCommand}"/>
<KeyBinding Key="Tab" Modifiers="Shift" Command="{Binding LastCommand}"/>
<KeyBinding Key="Escape" Command="{Binding ClearCommand}"/>
<KeyBinding Key="Enter" Command="{Binding EnterCommand}"/>
</UserControl.InputBindings>

Answer 4

(I know this is a late answer, but I still think it's usefull for people who want to solve this issue, without code behind)
A good way to do this in MVVM
First add the reference:
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
and from the NuGet package (MVVMLight):
xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras"
Than in your View:
<wpftoolkit:AutoCompleteBox Name="AutoCompleteBoxName">
<i:Interaction.Triggers>
<i:EventTrigger EventName="PreviewKeyDown">
<cmd:EventToCommand Command="{Binding AutoCompleteEnter}" PassEventArgsToCommand="True"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</wpftoolkit:AutoCompleteBox>
and than in your ViewModel :
public ICommand AutoCompleteEnter { get { return new RelayCommand<System.Windows.Input.KeyEventArgs>(Auto_Complete_Enter); } }
public void Auto_Complete_Enter(System.Windows.Input.KeyEventArgs e)
{
//Detect if key is 'Enter/Return' key
if ((e.Key == Key.Enter) || (e.Key == Key.Return))
{
Console.WriteLine("U have pressed the enter key");
}
}
Hope this will still help some people out.

Answer 5

So, I've spend a lot of time trying to get this thing to work. Other responses are certainly helpful and will get you to destination, but i have following issues with implementation:
I needed MVVM solution with an ability to bind Enter to Command within ViewModel, which means that Event Handlers was undesirable option.
I was trying to avoid adding additional dependencies to fix single event in a single control, so no MVVMLight.
Solution:
Pull copy of DonNetProjects.Input.Toolkit from github
Navigate to AutoCompleteBox/System/Windows/Controls/AutoCompleteBox.cs
Change overload of OnKeyDown method to following:
if (IsDropDownOpen)
{
if (SelectionAdapter != null)
{
SelectionAdapter.HandleKeyDown(e);
if (e.Handled)
{
return;
}
}
if (e.Key == Key.Escape)
{
OnAdapterSelectionCanceled(this, new RoutedEventArgs());
//e.Handled = true;
}
}
else
{
// The drop down is not open, the Down key will toggle it open.
if (e.Key == Key.Down)
{
IsDropDownOpen = true;
//e.Handled = true;
}
}
// Standard drop down navigation
switch (e.Key)
{
case Key.F4:
IsDropDownOpen = !IsDropDownOpen;
e.Handled = true;
break;
case Key.Enter:
if (IsDropDownOpen)
{
OnAdapterSelectionComplete(this, new RoutedEventArgs());
e.Handled = true;
}
break;
default:
break;
}
base.OnKeyDown(e);
Recompile to new DLL and reference it instead of original WPFToolkit.
Result:
If new version used as following:
xmlns:tk="clr-namespace:System.Windows.Controls;assembly=DotNetProjects.Input.Toolkit"
<tk:AutoCompleteBox ItemsSource="{Binding AvailableValues}" SelectedItem="{Binding SelectedValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<tk:AutoCompleteBox.InputBindings>
<KeyBinding Key="Enter" Command="{Binding AddValue}"/>
</tk:AutoCompleteBox.InputBindings>
</tk:AutoCompleteBox>
Resulting behavior is: if dropdown is open, Enter would be rerouted to it to complete selection, if dropdown is closed it will fire command in KeyBinding.

Answer 6

Alternatively, when using Caliburn Micro, you can simply use:
<Controls:AutoCompleteBox ItemsSource="{Binding Keywords}"
ValueMemberPath="Name"
Text="{Binding EnteredText, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
IsTextCompletionEnabled="True"
cal:Message.Attach="[Event PreviewKeyDown] = [Action AddTagOnEnter($eventArgs)]" />
Specifically, note the last line to attach your event. For some other method parameter options, see here.
Finally, define a public method in your ViewModel:
public void AddTagOnEnter(KeyEventArgs e)
{
if (e.Key != Key.Enter) return;
// Do something useful
}