Is there an equivalent of “None()” in LINQ?

Question

I\'ve been running into situations where I feel I\'m lacking a LINQ extension method which effectivelly checks if there is no match of the specified predicate in a collection. T

Answer 1

You can write your own Extension Method:

public static bool None(this IEnumerable<T> collection, Func<T, bool> predicate)
{
  return collection.All(p=>predicate(p)==false);
}

Or on IQueryable<T> as well

public static bool None(this IQueryable<T> collection, Expression<Func<TSource, bool>> predicate)
{
  return collection.All(p=> predicate(p)==false);
}

Answer 2

Even shorter version

static class LinqExtensions
{
    public static bool None<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate) => !source.Any(predicate);
}

Answer 3

None is the same as !Any, so you could define your own extension method as follows:

public static class EnumerableExtensions
{
    public static bool None<TSource>(this IEnumerable<TSource> source,
                                     Func<TSource, bool> predicate)
    {
        return !source.Any(predicate);
    }
}