C#•2y ago

Wpf Button CommandParameter

<Button Command="{Binding ClickCommandEvent}" CommandParameter="Jack"/> How commandParemeter value get wpf ?

20 Replies

twiner•2y ago

A command parameter is the same as other dependency properties. You bind it to the value you want to pass, otherwise it will pass as a string And then assuming that your ClickCommandEvent is an ICommand you can receive that parameter through the Execute methods parameter

twiner•2y ago

https://docs.microsoft.com/en-us/dotnet/api/system.windows.input.icommand

ICommand Interface (System.Windows.Input)

Defines a command.

SuperBrain•2y ago

@frknztrk you should use CommunityToolkit.Mvvm, it provides all the basic stuff you'll ever need.

frknztrk•2y ago

i want a simple build

SuperBrain•2y ago

It can't get any simpler than using CommunityToolkit.Mvvm. It provides a ready-made RelayCommand / AsyncRelayCommand implementations, as well as generic versions RelayCommand<T>/AsyncRelayCommand<T> (which are the ones you want when using CommandParameter) Docs reference: https://docs.microsoft.com/en-us/windows/communitytoolkit/mvvm/introduction Feel free to write everything on your own, but this would both save your time and provide best-in-class implementations.

frknztrk•2y ago

What I want is to get the CommandParameter data when I click the button in the dynamically created data source. Mainwindow.xaml

 <Window x:Class="lestplay.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:lestplay"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800" Loaded="Window_Loaded">

    <Window.Resources>

        <Style TargetType="ItemsControl" x:Key="den2">
            <Setter Property="SnapsToDevicePixels" Value="true" />
            <Setter Property="UseLayoutRounding" Value="True" />
            <Setter Property="ItemTemplate">
                <Setter.Value>
                    <DataTemplate>
                        <StackPanel>
                            <Button x:Name="lestplaybutton" Command="{Binding DisplayMessageCommand}" CommandParameter="{Binding Id}" Width="100" Height="50" Content="Furkan" />
                        </StackPanel>
                    </DataTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Window.Resources>
    <Grid>

        <ItemsControl x:Name="le2" Style="{DynamicResource den2}">
        </ItemsControl>
    </Grid>
</Window>

 <Window x:Class="lestplay.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:lestplay"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800" Loaded="Window_Loaded">

    <Window.Resources>

        <Style TargetType="ItemsControl" x:Key="den2">
            <Setter Property="SnapsToDevicePixels" Value="true" />
            <Setter Property="UseLayoutRounding" Value="True" />
            <Setter Property="ItemTemplate">
                <Setter.Value>
                    <DataTemplate>
                        <StackPanel>
                            <Button x:Name="lestplaybutton" Command="{Binding DisplayMessageCommand}" CommandParameter="{Binding Id}" Width="100" Height="50" Content="Furkan" />
                        </StackPanel>
                    </DataTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Window.Resources>
    <Grid>

        <ItemsControl x:Name="le2" Style="{DynamicResource den2}">
        </ItemsControl>
    </Grid>
</Window>

MessageViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace lestplay
{
    public class MessageViewModel
    {
        public List<Person> Persons { get; set; }

        public MessageCommand DisplayMessageCommand { get; set; }

        public MessageViewModel()
        {
            DisplayMessageCommand = new MessageCommand(DisplayMessage);
        }

        public void DisplayMessage(string messagetext)
        {
            MessageBox.Show(messagetext);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace lestplay
{
    public class MessageViewModel
    {
        public List<Person> Persons { get; set; }

        public MessageCommand DisplayMessageCommand { get; set; }

        public MessageViewModel()
        {
            DisplayMessageCommand = new MessageCommand(DisplayMessage);
        }

        public void DisplayMessage(string messagetext)
        {
            MessageBox.Show(messagetext);
        }
    }
}

Person.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace lestplay
{
    public class Person
    {
        public string Id { get; set; }
        public string Name { get; set; }

        public Person(string id, string name)
        {
            this.Id = id;
            this.Name = name;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace lestplay
{
    public class Person
    {
        public string Id { get; set; }
        public string Name { get; set; }

        public Person(string id, string name)
        {
            this.Id = id;
            this.Name = name;
        }
    }
}

MessageCommand.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace lestplay
{
    public class MessageCommand : ICommand
    {
        public event EventHandler? CanExecuteChanged;

        public Action<string> _execute;

        public MessageCommand(Action<string> execute)
        {
            _execute = execute;
        }

        public bool CanExecute(object? parameter)
        {
            return true;
        }

        public void Execute(object? parameter)
        {
            _execute.Invoke(parameter as string);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace lestplay
{
    public class MessageCommand : ICommand
    {
        public event EventHandler? CanExecuteChanged;

        public Action<string> _execute;

        public MessageCommand(Action<string> execute)
        {
            _execute = execute;
        }

        public bool CanExecute(object? parameter)
        {
            return true;
        }

        public void Execute(object? parameter)
        {
            _execute.Invoke(parameter as string);
        }
    }
}

twiner•2y ago

Seems like what you wrote here should work, though I think your message command class is gonna have problems

SuperBrain•2y ago

Yeah, your MessageCommand is basically ignoring the string parameter.

twiner•2y ago

Huh? I was referring to him not connecting back to CommandManager

twiner•2y ago

https://www.c-sharpcorner.com/UploadFile/20c06b/icommand-and-relaycommand-in-wpf/

ICommand and RelayCommand in WPF

This article provides a basic overview of commands in WPF. Here ICommand RelayCommand will be discussed.

twiner•2y ago

Only because I can't figure out where more official docs are I believe your mistaken Oh well. Can execute isn't checking the param

frknztrk•2y ago

Works when using outside of data template

frknztrk•2y ago

frknztrk•2y ago

Klarth•2y ago

The issue is that your Command binding is incorrect. It doesn't have to do with the CommandParameter. I suggest not putting the <DataTemplate> into your resources if you can avoid it, so you can have a simpler ElementName binding instead of RelativeSource ancestor binding. Currently, the binding is looking for the command on Person because that's the local DataContext within the <DataTemplate>.

<Window x:Class="lestplay.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:lestplay"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800" Loaded="Window_Loaded">

    <Window.Resources>
        <Style TargetType="ItemsControl" x:Key="den2">
            <Setter Property="SnapsToDevicePixels" Value="true" />
            <Setter Property="UseLayoutRounding" Value="True" />
        </Style>
    </Window.Resources>

    <Grid>
        <ItemsControl x:Name="le2" Style="{StaticResource den2}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Button Command="{Binding DataContext.DisplayMessageCommand, ElementName=le2}" CommandParameter="{Binding Id}" Width="100" Height="50" Content="Furkan" />
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </Grid>
</Window>

<Window x:Class="lestplay.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:lestplay"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800" Loaded="Window_Loaded">

    <Window.Resources>
        <Style TargetType="ItemsControl" x:Key="den2">
            <Setter Property="SnapsToDevicePixels" Value="true" />
            <Setter Property="UseLayoutRounding" Value="True" />
        </Style>
    </Window.Resources>

    <Grid>
        <ItemsControl x:Name="le2" Style="{StaticResource den2}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Button Command="{Binding DataContext.DisplayMessageCommand, ElementName=le2}" CommandParameter="{Binding Id}" Width="100" Height="50" Content="Furkan" />
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </Grid>
</Window>

This is how I would rewrite it so the Button command works. I'd probably get rid of the style altogether.

frknztrk•2y ago

I think it's okay, thank you, but I have to use style because I'm getting my data dynamically. but why does it not see the element name in such a render

private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            List<Person> prn = new List<Person>();
            prn.Add(new Person() { Name = "furkan", Id = "ui-dyanmic" });

            ItemsControl itemsControl = new ItemsControl();
            itemsControl.Style = (Style)FindResource("le1");
            itemsControl.Name = "le1";

            itemsControl.ItemsSource = prn;

            maingrid.Children.Add(itemsControl);
            DataContext = new MessageViewModel();
        }

private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            List<Person> prn = new List<Person>();
            prn.Add(new Person() { Name = "furkan", Id = "ui-dyanmic" });

            ItemsControl itemsControl = new ItemsControl();
            itemsControl.Style = (Style)FindResource("le1");
            itemsControl.Name = "le1";

            itemsControl.ItemsSource = prn;

            maingrid.Children.Add(itemsControl);
            DataContext = new MessageViewModel();
        }

frknztrk•2y ago

Klarth•2y ago

Because you didn't follow the advice. There's no reason this needs to be a style. You can't access element names like that when you're in .Resources, AFAIK. Which means you now have to write a RelativeSource ancestor binding which looks something like:

<Button Command="{Binding DataContext.DisplayMessageCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ItemsControl}}}"
    CommandParameter="{Binding Id}" Width="100" Height="50" Content="Furkan" />

<Button Command="{Binding DataContext.DisplayMessageCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ItemsControl}}}"
    CommandParameter="{Binding Id}" Width="100" Height="50" Content="Furkan" />

frknztrk•2y ago

sorry i am new to .net i am missing some points

Klarth•2y ago

It's a complicated binding, but you need that indirection if the data isn't located on the current DataContext.

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Wpf Button CommandParameter