title: How to make a nullable property in EF Codefirst?
body: <p>I have two POCOs in my "Bookshelf" test application:</p>
  
  <pre><code>/// &lt;summary&gt;
  /// Represents a book
  /// &lt;/summary&gt;
  public class Book
  {
      public int ID { get; set; }
      public string Title { get; set; }
      public string Author { get; set; }
      public string ISBN { get; set; }
      public virtual Loaner LoanedTo { get; set; }
  }
  
  /// &lt;summary&gt;
  /// Represents a Loaner
  /// &lt;/summary&gt;
  public class Loaner
  {
      public int ID { get; set; }
      public string Name { get; set; }
      public virtual ICollection&lt;Book&gt; Loans { get; set; }
  }
  </code></pre>
  
  <p>Is there a way that my LoanedTo could be nullable? I mean a book isn't always loaned, right! I tried</p>
  
  <pre><code>public virtual Loaner? LoanedTo { get; set; }
  </code></pre>
  
  <p>But I get:
  The type 'RebtelTests.Models.Loaner' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable'</p>
  
  <p>So I must be thinking wrong somewhere, but I can't figure it out. Probably easy squeeze for you guys.</p>