CODEWITHSUNDEEP
c#xamarinxamarin.uwp
Leo
Leo

Reputation: 49

About CollectionView Deselect the SelectedItem

How to deselect the SelectedItem if the selected item does not meet the requirement using the collection view? Do I have to create a custom collection view? How to do on the override the OnPropertyChanged method? Thank you.

Upvotes: 0

Views: 2969

Answers (3)

Mahab
Mahab

Reputation: 198

Working algorithm upon https://stackoverflow.com/a/64457513/1894630 solution:

private void CollectionView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    CollectionView collectionV = sender as CollectionView;
    Viewmodels.Slotviewmodel current;
    if (e.CurrentSelection.Count == 0 || e.PreviousSelection.Count == 0)
    {
        if (e.CurrentSelection.Count != 0)
        {
            current = e.CurrentSelection[0] as Viewmodels.Slotviewmodel;
            if (!current.available)
            {
                collectionV.SelectedItem = null;
            }
        }
        return;
    }
    current = e.CurrentSelection[0] as Viewmodels.Slotviewmodel;
    if (!current.available) //meet requirement
    {
        collectionV.SelectedItem = e.PreviousSelection[0];
    }
}

Upvotes: 0

zafar
zafar

Reputation: 2064

If you are using MVVM design pattern, then you should be able to track the CollectionView's SelectedItem property in your ViewModel, essentially using Binding in TwoWay mode. Here is the sample:

YourView.xaml:

<CollectionView ItemsSource="Items" SelectedItem="SelectedItem"/>

YourViewModel.cs

public IList<string> Items{get;set;}
private string _selectedItem;
public string SelectedItem
{
  get=>_selectedItem;
  set
    {
      //if selected item is the same one, return
      if(Equals(value,_selectedItem)) return;
    
      //if the item doesn't meet the requirement, don't update the selected item in the view model
      if(!ItemMeetsYourRequirement(value))
      {
        //raise property changed to notify view to change the selected item to previous one
        OnPropertyChanged(nameof(SelectedItem));
        return;
      }
      //if you are here, the selected item is changed and meets your requirements;
      _selectedItem = value;
      OnPropertyChanged(nameof(SelectedItem);
    }
} 

private bool ItemMeetsYourRequirement(string item) => return true; //add your logic here

Upvotes: 2

nevermore
nevermore

Reputation: 15816

You can deselecte the SelectedItem in the CollectionView_SelectionChanged event:

private void CollectionView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{

    //var previous = e.PreviousSelection;
    //var current = e.CurrentSelection;

    CollectionView collectionV = sender as CollectionView;

    if ()//meet requirement
    {

    }
    else
    {
        //not meet requirement
        collectionV.SelectedItem = null;

    }
}

And in xaml:

<CollectionView SelectionChanged="CollectionView_SelectionChanged" SelectionMode="Single">
    <CollectionView.ItemsSource>
        <x:Array Type="{x:Type x:String}">
            <x:String>Baboon</x:String>
            <x:String>Capuchin Monkey</x:String>
            <x:String>Blue Monkey</x:String>
        </x:Array>
    </CollectionView.ItemsSource>
</CollectionView>

Upvotes: 2

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