title: How to save an Expando object field with Entity Framework Core
body: <p>I have a class with an ExpandoObject field to allow users of my class
  to add their properties to it.   </p>
  
  <pre><code>public class Employee
  {
      public dynamic ExtendedProperties = new ExpandoObject();
  
      public int Id { get; set; }
  
      public string Name { get; set; }
  }
  </code></pre>
  
  <p>I want to map these extended properties to columns in the database.
  How can I save these extended properties with Entity Framework Core 2.1 ?</p>