title: EFCode First Property Null problem
body: <p>I use EFCode First in asp.net mvc 3 model. (Entity Framework 4.0 and EFCode First 0.8)
  The model is defined like below:</p>
  
  <pre><code>public class User
  {
      [Key]
      public int Id { get; set; }
      public string Name { get; set; }
      public int WorkedYears { get; set; }
  }
  </code></pre>
  
  <p>when use <code>db.Users.Find(1)</code>, will throw this error:</p>
  
  <blockquote>
    <p>The 'WorkedYears' property on 'User'
    could not be set to a 'null' value.
    You must set this property to a
    non-null value of type 'Int32'.</p>
  </blockquote>
  
  <p>Note: user.Id=1 exists in database, and WorkedYears of the record is NULL.
  if I set the WorkedYears = 0 in the database, the error will disappear, 
  and also if I define the property like:<code>public int? WorkedYears{get; set;}</code>, the error will disapper too.
  but I don't want use int?, and also want the column keep NULL if not set.
  So is there any other solution to fix it?</p>
  
  <p>Thanks a lot.</p>