如何将WPF ListBox项目与字符串进行比较？

Question

I've seen some examples with sorting and filtering using colllectionView but none doing in a comparative logical way.

example:

// Button event to send an item from LB1 to LB2
private void BaddProduct_Click(object sender, RoutedEventArgs e)
{
  if(Lb2.Items.Contains("item"))
  {
   MessageBox.Show("This item is already there!");
  }
  //second example
   if(Lb2.Items.StartWith("item"))
   {
     MessageBox.Show("This item is already there!");
   }
 }

The code works for winforms. Is there an approach for WPF?

Thank you!

Answer 1

This code would work in the .xaml.cs file as well, as the 'code behind' has direct reference to all named, non-template WPF items.

If you would like the data sources to be a little more dynamic, I suggest using IEnumerable collections to bind your ItemSource to, and then you can perform all filtering using LINQ.

(edit: fixed typo 'datasources' to 'data sources')

Answer 2

For anyone that needs this approach:

//called by the collectionView
private bool UserFilter(object item)
{
        string produtoItem;
         //my LB1. With dynamic type i am gettting the item selected. 
        dynamic selectProdutoItem = LbProdutoPlano.SelectedItem;
        produtoItem = selectProdutoItem.produtoPlanoNome;

        if (String.IsNullOrEmpty(produtoItem))
        {
            return true;
        }
        else
        {
            //this will do a comparative logic on my selected item on LB 1. fichaProduto is my class and fichaProdutoProdutoNome a string of that class that is the same string or the item in LB1, produtoItem. 
            return ((item as fichaProduto).fichaProdutoProdutoNome.IndexOf(produtoItem, StringComparison.OrdinalIgnoreCase) >= 0);
        }
}
// a button to add an item from LB1 to LB2. 
private ButtonAdd_Click()
{
        //created the collectionView in here having the itemSource the LB2 that is already binded. 
         CollectionView viewFiltro = (CollectionView)CollectionViewSource.GetDefaultView(LbProdutoPlanoEscolhido.ItemsSource);
         // this is the key of this logic. The View will do a comparative logic from the retur of the UserFilter method.
         viewFiltro.Filter = UserFilter;
         // so if the View found it, it will count 1. 
         if (viewFiltro.Count == 1)
         {
             MessageBox.Show("This product is already in the LB2.");
         }
         else
         {
         // add the item into LB 2. 
         }
}

In this way, we don´t have to compare observable´s Collection for none of the ListBoxes. Just use the predicate Filter of the CView and check the result of it using the property COUNT. If it is 1, that means the filter seach for an item in LB1 and found it on the LB 2.