为什么绑定到文本框的命令无法在WPF中触发？

Question

I've bound the textbox to a command using the trigger but nothing appears to happen when the user hits enter on the keyboard. Why would that be? What I want to happen is when the user hits enter it appends the name to the list and clears the input field.

The main areas of focus are here: xaml snippet

   <TextBox Grid.Row="0" Text="{Binding InputText, UpdateSourceTrigger=PropertyChanged}">
            <TextBox.InputBindings>
                <KeyBinding Key="Enter" Command="{Binding Path=CmdSomething, UpdateSourceTrigger=PropertyChanged}"/>
            </TextBox.InputBindings>
        </TextBox>

and its calling this command in the main view model:

 public void CmdSomething()
        {
            Console.WriteLine(InputText);
        }

Below is the code for the entire project just in case someone needs it to test.

PROJECT CODE

VNodes.cs

namespace WpfApplication1
{
    public class VNode
    {
        public string Name { get; set; }
    }
}

MainWindow.xaml

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        xmlns:local="clr-namespace:WpfApplication1">

    <Window.DataContext>
        <local:MainViewModel/>
    </Window.DataContext>

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="30"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <TextBox Grid.Row="0" Text="{Binding InputText, UpdateSourceTrigger=PropertyChanged}">
            <TextBox.InputBindings>
                <KeyBinding Key="Enter" Command="{Binding Path=CmdSomething, UpdateSourceTrigger=PropertyChanged}"/>
            </TextBox.InputBindings>
        </TextBox>

        <ListBox Grid.Row="1" Background="LightBlue" ItemsSource="{Binding VNodes}">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <WrapPanel>
                        <TextBlock Text="{Binding Name}" FontWeight="Bold" />
                    </WrapPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>

MainViewModel

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.CompilerServices;
using System.Collections.ObjectModel;


namespace WpfApplication1
{
    public class MainViewModel : ObservableObject
    {
        private ObservableCollection<VNode> _vnodes;
        public ObservableCollection<VNode> VNodes
        {
            get { return _vnodes; }
            set
            {
                _vnodes = value;
                NotifyPropertyChanged("VNodes");
            }
        }

        private string _inputText = "";
        public string InputText
        {
            get { return _inputText; }
            set
            {
                if (value != _inputText)
                {
                    _inputText = value;
                }
            }
        }

        public void CmdSomething()
        {
            Console.WriteLine(InputText);
        }

        public MainViewModel()
        {
            //hard coded data for testing
            VNodes = new ObservableCollection<VNode>();
            List<string> names = new List<string>() { "Tammy", "Doug", "Mike", "Joey", "Leslie", "Emily", "Tom" };

            foreach(string name in names)
            {
                VNode item = new VNode();
                item.Name = name;
                VNodes.Add(item);
            }
        }
    }
}

ObservableObjects.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace WpfApplication1
{
    public class ObservableObject : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void NotifyPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}

Answer 1

CmdSomething in your code is not a ICommand but instead just a function.

Now there are two ways to make it work in your case.

Create an ICommand. Wonderful tutorial .

If MyCommand is a property of type ICommand in your ViewModel, then to bind your Custom Command :

<TextBox.InputBindings>
      <KeyBinding Key="Enter" Command="{Binding MyCommand, Mode=OneWay}" />
</TextBox.InputBindings>

And if you want to call your function, then you can use CallMethodAction behavior. Discussion . You can search google for more tutorials.

For your current issue, this works without any issues whatsoever :

xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"

       <TextBox x:Name="textBox" Margin="144,80,288,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Height="32">
            <i:Interaction.Triggers>
                <ei:KeyTrigger Key="Return"> <!-- Note Blend Behaviors don't use Enter, instead use Return value -->
                    <ei:CallMethodAction TargetObject="{Binding DataContext, RelativeSource={RelativeSource AncestorType={x:Type Window}, Mode=FindAncestor}}" MethodName="CmdSomething"/>
                </ei:KeyTrigger>
            </i:Interaction.Triggers>
        </TextBox>

Good discussion