[SOLVED] How to retrieve the elements in a List with a lambda expression without for o foreach

Issue

I’m try to pass an entity to a method by parameter, but I don’t want to do a for or foreach. How can I pass this parameter without using for or foreach with a lambda expression?

This is my code:

private async Task SaveParents()
{
  try
  {
     await Task.Run(() => {
            List<Parent> parents = new List<Parent>();
            parents.AddRange(GetParents();
            parents.AddRange(GetParentsTwo();
            _iData.SaveParents(parents); //Here I want to pass each of the elements with lambda
    });
  }
}

Thank you 😀

Solution

Out of the box, LINQ doesn’t support what you are trying to do.

If you’re really adamant about this, though, it’s a trivial matter to write an extension method that will do this for you:

public static class LinqExtensions
{
    public static void ForEach(this IEnumerable<T> sequence, 
        Action<T> action)
    {
        forEach(var item in sequence)
        {
            action(item);
        }
    }
}

Then in your code sample (note I had to change the method signature to take a single item):

private async Task SaveParents()
{
  try
  {
     await Task.Run(() => {
            List<Parent> parents = new List<Parent>();
            parents.AddRange(GetParents();
            parents.AddRange(GetParentsTwo();

            parents.ForEach(p => _iData.SaveParent);
    });
  }
}

Note that just because you can do this does not necessarily mean you should. Microsoft’s argument against including IEnumerable<T>.ForEach is that queries should not have side-effects. That’s a fairly compelling argument.

Answered By – Mike Hofer

Answer Checked By – Clifford M. (BugsFixing Volunteer)