title: AutoMapper ProjectTo ignoring .Include
body: <p>I'm learning Automapper, and EF Core, and stumbled onto a problem, while trying to model get-only property, which is calculated based on navigation property.
  I'm having two models:</p>
  
  <pre><code>public class Parent 
  {
      public int Id {get;set;}
      public string Name {get;set;}
      public ICollection&lt;Child&gt; Childs {get;set;}
      public int WantedChildCount {get{return Childs?.Count(c=&gt;c.Type!=1)??0;}
  }
  public class Child
  {
      public int Id {get;set;}
      public string Name {get;set;}
      public int Type {get;set;}
  }
  </code></pre>
  
  <p>One DTO:</p>
  
  <pre><code>public class VM
  {
      public string Name{get;set;}
      public int WantedCount{get;set;}
  }
  </code></pre>
  
  <p>And trying to automap VM from Parent like:</p>
  
  <pre><code>var c = context.Parents.Include(p =&gt; p.Childs).ProjectTo&lt;VM&gt;().FirstOrDefault();
  </code></pre>
  
  <p>Automapper configured like this:</p>
  
  <pre><code>Mapper.Initialize(cfg=&gt;
      cfg.CreateMap&lt;Parent, VM&gt;()
      .ForMember(d=&gt;d.WantedCount, o =&gt; o.MapFrom(s=&gt;s.WantedChildCount));
  </code></pre>
  
  <p>The problem is that in resulting VM field WantedCount isn't populated. In logs I've found message </p>
  
  <pre><code>The Include operation for navigation: 'p.Childs' was ignored because the target navigation is not reachable in the final query results. 
  </code></pre>
  
  <p>It's easy so split this operation into two separate: first take Parent, and then Mapper.Map. 
  Also, it could work when changing Map like this:</p>
  
  <pre><code>cfg.CreateMap&lt;Parent, VM&gt;()
      .ForMember(d=&gt;d.WantedCount, o =&gt; o.MapFrom(s=&gt;s.Childs(c=&gt;c.Type!=1));
  </code></pre>
  
  <p>But this way I'll ignore get-only property in model totally.
  I'd like to understand what the problem is, and how could I solve it.</p>
  
  <p>Or maybe I should even somehow move calculation to DB side? But I'd like to avoid storing this property in database.</p>