SafeWhere not working?

specimen151 · April 8, 2022, 10:25am

I’m using the SafeWhere, but today I got a surprise. It doesn’t seem to do what I’d expect (implement a null check).

Here’s the link:

ServiceStack/ServiceStack/blob/e6e539c3d20836e4695e53d03a55c028f4e29db3/ServiceStack.Text/src/ServiceStack.Text/ListExtensions.cs#L38


    }
    return StringBuilderThreadStatic.ReturnAndFree(sb);
}


public static bool IsNullOrEmpty<T>(this List<T> list)
{
    return list == null || list.Count == 0;
}


//TODO: make it work
public static IEnumerable<TFrom> SafeWhere<TFrom>(this List<TFrom> list, Func<TFrom, bool> predicate)
{
    return list.Where(predicate);
}


public static int NullableCount<T>(this List<T> list)
{
    return list == null ? 0 : list.Count;
}


public static void AddIfNotExists<T>(this List<T> list, T item)

Couldn’t find it in the documentation. Is it supposed to be used like this:

mylist.SafeWhere(…)

because it fails if mylist == null.

Tried this:

mylist?.SafeWhere(…)

but no luck. Also:

mylist.Safe().Where/Find/etc.

but Safe() converts the List to IEnumerable, which doesn’t have the Find/Where LINQ? extension methods.

Made my own extension method in the end:

public static List<T> SafeX<T>(this List<T> list)
        {
            if (list != null) return list;
            else return new List<T>();
        }

mythz · April 8, 2022, 10:25am

No idea what the purpose of this API was for as it has no usages in the code-base, but it looks like it was added from when we migrated from google code in 2010.

I’ve added a guard against nulls in this commit, but I’d say it’s irrelevant now that C# has null guards so you should probably use list?.Where(...) instead or if you want an empty collection if null you can use list.Safe().Where(...)