how to use SelectionChangedCommand..(collectionview) to viewmodiel?

Question

Hi guys

How can I transfer this code to view model by Bindnig?

private async void inboxList_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
try {
if (e.CurrentSelection != null)
{
var messageData = e.CurrentSelection.LastOrDefault() as InboxModel;
msgID = messageData.Msg_ID.ToString();
}

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

You can Use SelectionChangedCommand and SelectionChangedCommandParameter to transfer inboxList_SelectionChanged to view model by Binding.

For example, I have following XAML layout.

   <CollectionView x:Name="MyCollectionView"  HeightRequest="170"   
                 WidthRequest="200"   ItemsSource="{Binding Monkeys}" SelectionMode="Single"  SelectionChangedCommand="{Binding  SelectedTagChangedCommand}" SelectionChangedCommandParameter="{Binding SelectedItem, Source={x:Reference MyCollectionView}}">  
               <CollectionView.ItemTemplate>  
                   <DataTemplate>  
                       <Grid Padding="10">  
                           <Grid.RowDefinitions>  
                               <RowDefinition Height="Auto" />  
                               <RowDefinition Height="Auto" />  
                           </Grid.RowDefinitions>  
                           <Grid.ColumnDefinitions>  
                               <ColumnDefinition Width="Auto" />  
                               <ColumnDefinition Width="Auto" />  
                           </Grid.ColumnDefinitions>  
                           
                           <Label Grid.Column="1"  
                          Text="{Binding Name}"  
                          FontAttributes="Bold" />  
                           
                       </Grid>  
                   </DataTemplate>  
               </CollectionView.ItemTemplate>  
           </CollectionView>  

Here is layout background code.

   public MainPage()  
           {  
               InitializeComponent();  
              this.BindingContext = new MyViewModel();  
           }  

Here is my MyViewModel.cs, When item was changed, SelectedTagChangedCommand will be executed, we can get the select item by Monkey monkey= sender as Monkey;

   using System;  
   using System.Collections.Generic;  
   using System.Collections.ObjectModel;  
   using System.Text;  
   using System.Windows.Input;  
   using Xamarin.Forms;  
     
   namespace App111  
   {  
     
       public class MyViewModel  
       {  
     
           public Command SelectedTagChangedCommand  
           {  
               get  
               {  
                   return new Command((sender) =>  
                   {  
                       Monkey monkey= sender as Monkey;  
     
                       Console.WriteLine("Select item in Colletionview"+ monkey.Name);  
                   });  
               }  
           }  
     
           public ObservableCollection<Monkey> Monkeys { get; set; }  
     
           //  public int  { get; set; }  
           public MyViewModel()  
           {  
               Monkeys = new ObservableCollection<Monkey>();  
               Monkeys.Add(new Monkey() { Name = "test1" });  
               Monkeys.Add(new Monkey() { Name = "test2" });  
               Monkeys.Add(new Monkey() { Name = "test3" });  
               Monkeys.Add(new Monkey() { Name = "test4" });  
               
           }  
       }  
     
       public class Monkey  
       {  
     
           public string Name { get; set; }  
       }  
   }  

Best Regards,

Leon Lu

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Answer 2

Thank you Mr.Leon Lu