Lambda expression C# Union Where

Question

I have objects of class

public class Person
    {
        public string Error { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

some have Error (and no Name and Age) some have no Error (and Name and Age)

Person[] p1 = new Person[] { new Person { Error = "Error1" }, new Person { Name = "Name1", Age = 1 } };



Person[] p2 = p1
                .Where(c => string.IsNullOrEmpty(c.Error))
                .Select(
                    c => new Person { Name = c.Name, Age = c.Age }
                 ).ToArray()
                 Union()
                .Where(d => !string.IsNullOrEmpty(d.Error))
                .Select(
                    d => new Person { Error = d.Error }
                 ).ToArray()

I need create second array p2, where I can select all persons objects from p1 which have Error, and Union all persons from same p1 which have no Error.

I need something like in code above, but it's not working. How can I write it in one lambda clause?

Thanks a lot?

Answer 1

p1.Where(c => string.IsNullOrEmpty(c.Error))
  .Union(p1.Where(d => !string.IsNullOrEmpty(d.Error)))
  .ToArray()

You need to add the second IEnumerable inside the .Union. And no need to project again since the objects are already the type you need.

Although it's kind of moot in this case, the result is the same as p1