SearchBox crashing

Question

Hi,

I have ListView in my Xamarin Forms app with SearchBox.

My ListView Bidning is like this:

SchedulesFlights.Root data = JsonSerializer.Deserialize<SchedulesFlights.Root>(result);  

and I am trying to use the SearchBox using below code:

private void OnFilterTextChanged(object sender, Xamarin.Forms.TextChangedEventArgs e)  
{  
    searchBar = (sender as SearchBar);  
  
    if (ListViewSchedulesArrival.DataSource != null && ListViewSchedulesArrival.IsVisible == true)  
    {  
        ListViewSchedulesArrival.DataSource.Filter = FilterService;  
        ListViewSchedulesArrival.DataSource.RefreshFilter();  
    }  
    else if (ListViewSchedulesDeparture.DataSource != null && ListViewSchedulesDeparture.IsVisible == true)  
    {  
        ListViewSchedulesDeparture.DataSource.Filter = FilterService;  
        ListViewSchedulesDeparture.DataSource.RefreshFilter();  
    }  
}  
  
private bool FilterService(object obj)  
{  
    if (searchBar == null || searchBar.Text == null)  
    {  
        return true;  
    }  
  
    var list = obj as SchedulesFlights.Response;  
  
    if (list.flight_iata.ToLower().Contains(searchBar.Text.ToLower()) || list.status.ToLower().Contains(searchBar.Text.ToLower()))  
    {  
        return true;  
    }  
    else  
    {  
        return false;  
    }  
}  

but every time the user types anything to search then the app will crash with the following error:

System.NullReferenceException: Object reference not set to an instance of an object
at Skyye.Schedules.FilterService (System.Object obj) [0x0002a] in /Users/jassim/Projects/Skyye/Skyye/Skyye/Schedules.xaml.cs:217
at Syncfusion.DataSource.DataSource.FilterRecord (System.Object record) [0x0000e] in <c4dd369a0b6a40d7857f6180c564514f>:0
at Syncfusion.DataSource.DataSource.InitializeItems () [0x00025] in <c4dd369a0b6a40d7857f6180c564514f>:0
at Syncfusion.DataSource.DataSource.Refresh () [0x00109] in <c4dd369a0b6a40d7857f6180c564514f>:0
at Syncfusion.DataSource.DataSource.RefreshFilter () [0x0009b] in <c4dd369a0b6a40d7857f6180c564514f>:0
at Skyye.Schedules.OnFilterTextChanged (System.Object sender, Xamarin.Forms.TextChangedEventArgs e) [0x0004a] in /Users/jassim/Projects/Skyye/Skyye/Skyye/Schedules.xaml.cs:199
at Xamarin.Forms.InputView.OnTextChanged (System.String oldValue, System.String newValue) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\InputView.cs:98
at Xamarin.Forms.InputView+<>c.<.cctor>b__49_0 (Xamarin.Forms.BindableObject bindable, System.Object oldValue, System.Object newValue) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\InputView.cs:9
at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00120] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:512
at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x00173] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:446
at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:383
at Xamarin.Forms.Element.SetValueFromRenderer (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:248
at Xamarin.Forms.Element.Xamarin.Forms.IElementController.SetValueFromRenderer (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:244
at Xamarin.Forms.Platform.iOS.SearchBarRenderer.UpdateOnTextChanged () [0x00000] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\SearchBarRenderer.cs:352
at Xamarin.Forms.Platform.iOS.SearchBarRenderer.OnTextChanged (System.Object sender, UIKit.UISearchBarTextChangedEventArgs a) [0x00013] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\SearchBarRenderer.cs:227
at UIKit.UISearchBar+_UISearchBarDelegate.TextChanged (UIKit.UISearchBar searchBar, System.String searchText) [0x00011] in /Users/builder/azdo/_work/1/s/xamarin-macios/src/build/ios/native/UIKit/UISearchBar.g.cs:1387
at at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
at UIKit.UIApplication.Main (System.String[] args, System.Type principalClass, System.Type delegateClass) [0x0003b] in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:85
at Skyye.iOS.Application.Main (System.String[] args) [0x00001] in /Users/jassim/Projects/Skyye/Skyye/Skyye.iOS/Main.cs:17

Answer 1

Probably obj is not a SchedulesFlights.Response. Clarify the real type of obj. Maybe you can write:

 var list = (SchedulesFlights.Root)obj;

and adjust the code.