title: LINQ Projecting relation properties with null
body: <p>I want to select items from a table, these items have relation properties, can I projecting them if they could be nullable (ie like left join)? And if not how I can workaround this? </p>
  
  <pre><code>class MyProducer
  {
    ....
  }    
  
  Model model = new Model();
  var q = 
      model.Products
      .Select(
        p =&gt; 
          new 
          { 
              id = p.Id, 
              producer = p.Producer != null ? new MyProducer { id = p.Producer.Id } : null 
          });
  
  var r = q.ToArray();
  </code></pre>
  
  <p>When I execute this code I have exception </p>
  
  <blockquote>
    <p>Unable to create a null constant value of type 'MyProducer'.  Only
    entity types, enumeration types or primitive types are supported in
    this context.</p>
  </blockquote>