How to avoid NULL here?

Question

Hi,

I have this if code:

if (list.category_name.ToLower().Contains(searchBar.Text.ToLower()) || list.sub_category_name.ToLower().Contains(searchBar.Text.ToLower()) || list.search_keyword.ToLower().Contains(searchBar.Text.ToLower()))

but it keeps throwing null error when any of the fields is null.

my class is like this:

public string search_keyword { get; set; }

Kindly help..

Answer 1

You can just check each field before you use them:

if (list.category_name != null && list.category_name.ToLower().Contains(searchBar.Text.ToLower())
    || list.sub_category_name != null && list.sub_category_name.ToLower().Contains(searchBar.Text.ToLower())
    || list.search_keyword != null && list.search_keyword.ToLower().Contains(searchBar.Text.ToLower()))

Or you could use the null-conditional operator if you prefer that:

if (list.category_name?.ToLower().Contains(searchBar.Text.ToLower() == true)
    || list.sub_category_name?.ToLower().Contains(searchBar.Text.ToLower() == true)
    || list.search_keyword?.ToLower().Contains(searchBar.Text.ToLower()) == true)