How to avoid null in IF

Question

Hi,

I have the following line that checks with IF when typing in a Searchbox control:

if (list.flight_iata.ToLower().Contains(searchBar.Text.ToLower()) || list.status.ToLower().Contains(searchBar.Text.ToLower()))  

How can I determine null value and resume without error if null is found?

Thanks,
Jassim

Answer 1

Add an extension method:

namespace System  
{  
    public static class StringExtensions  
    {  
        public static string SafeTrim(this string value, params char[] trimChars)  
        {  
            if (value == null)  
            {  
                return string.Empty;  
            }  
            else  
            {  
                return value.Trim(trimChars);  
            }  
        }  
    }  
}  
  

Update your IF condition as below:

if (list != null &&(list.flight_iata.SafteTrim().ToLower().Contains(searchBar.Text.ToLower()) || list.status.SafteTrim().ToLower().Contains(searchBar.Text.ToLower())))  

The SafeTrim() method will return a string.Empty if the specified string is null.

If right, please Accept.
Enjoy Programming!!!

Answer 2

or just use c#

 if (list.flight_iata?.ToLower().Contains(searchBar.Text?.ToLower() ?? "") ?? false  
 || list.status?.ToLower().Contains(searchBar.Text?.ToLower() ?? "") ?? false)