situation : i have a event handler of a search textbox in MainPage.xaml.cs
void src_textbox_TextChanged(object sender, TextChangedEventArgs e)
{
TextBox tb = sender as TextBox;
listBoxTextItems.ItemsSource = App.ViewModel.Problems.Where(w => w.ProblemName.ToLower().Contains(tb.Text));
}
listBoxTextItems : name of listbox control ,
Problems : name of collection instantiated in MainViewModelClass constructor ,
this code shows only those objects whose ProblemName property contains the letters typed in textbox .
Problem : what i want is that this code should also show those objects whose ProblemDesc property contains the letters typed in textbox .
i tried something like this :
listBoxTextItems.ItemsSource = App.ViewModel.Problems.Where((w => w.ProblemName.ToLower().Contains(tb.Text))||(w => w.ProblemDesc.ToLower().Contains(tb.Text)));
but i get an error saying "operator || cannot be applied to operands of type lambda expression and lambda expression. can anyone suggest me correct code ?
You don't need to specify lambda parameter whenever you need to use it. Just specify it once:
App.ViewModel.Problems.Where(w => w.ProblemName.ToLower().Contains(tb.Text) ||
w.ProblemDesc.ToLower().Contains(tb.Text));
When you specify w second time, you are creating a new lambda expression therefore you get the error.Simple syntax of lambda expression is:
(input parameters) => expression
In this case you have only one input parameter which is w, you need to specify it only once so you will be using the same parameter and create only one lambda expression which returns a boolen result.
You can refer to documentation for more detailed explanation about lambda expressions: