title: EF Core Deleting related entities on One To One relationship
body: <p>I have a one to one relationship set up on ef core. When i try to delete <code>Article</code>
  entity I need to cascade <code>MediPlan</code> since it is <code>one to one</code> relationship. When I Delete <code>Article</code>, <code>MediaPlan</code> is not getting removed.</p>
  
  <p>Here is set up.</p>
  
  <pre><code>public class Article
  {
      public int Id { get; set; }
  
      public int MediaPlanId { get; set; }
  
      public MediaPlan MediaPlan { get; set; }
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>public class MediaPlan
  {
      public int Id { get; set; }
      public Article Article { get; set; }
  }
  </code></pre>
  
  <p>Context </p>
  
  <pre><code>modelBuilder.Entity&lt;Article&gt;().HasOne(x =&gt; x.MediaPlan).WithOne(x =&gt; x.Article);
  </code></pre>
  
  <p>Code to delete</p>
  
  <pre><code>var article = await _db.Articles
              .Include(x=&gt;x.MediaPlan)
              .SingleAsync(x=&gt;x.Id == id);
  _db.Articles.Remove(article);
  await _db.SaveChangesAsync();
  </code></pre>
  
  <p>Do I have to set a FK on <code>MediaPlan</code> entity as well?</p>
  
  <p>Thank you!</p>