How to get object properties from IEnumerable<object[]> using LINQ c#

I have one List with collection of object arrays.I am using following code to collect all EmployeeIDs

List<string> employeeIds= new List<string>();
var employeeFields = employees.Items.Select(c => c.EmployeeFields ).ToList();
foreach(var objectArray in employeeFields )
{
    foreach(var item in objectArray)
    {
        if(item is EmployeeID)
        {
            employeeIds.Add(item.ToString());
        }
    }
}

 public partial class EmployeeId 
  { private string itemField; /// <remarks/>           
    public string Item { get { 
  return this.itemField; } 
  set { this.itemField = value; }
 }

}

Here EmployeeFields consist of an object array.How can i do this in single linq query Live Example http://rextester.com/VJB79010

Jon Skeet
people
quotationmark

You can use SelectMany and OfType to do this in one go:

var employeeIds = employees.Items
    .Select(c => c.EmployeeFields)     // Select the fields per employee
    .SelectMany(fields => fields)      // Flatten to a single sequence of fields
    .OfType<EmployeeID>()              // Filter to only EmployeeID fields
    .Select(id => id.Item)             // Convert to strings
    .ToList();                         // Materialize as a list

Or slightly fewer lines of code, but perhaps more tricky to understand:

var employeeIds = employees.Items
    .SelectMany(c => c.EmployeeFields) // Select the fields per employee and flatten
    .OfType<EmployeeID>()              // Filter to only EmployeeID fields
    .Select(id => id.Item)             // Convert to strings
    .ToList();                         // Materialize as a list

people

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