title: Collection in model missing the data
body: <p>I have this page which manages restaurants and reviews. I can create Restaurants and reviews perfectly, but when I want to link a review into a collection in the restaurant, this disapear when fetching it from the view</p>
  
  <p>This is my restaurant model, where i want to storage the reviews of each restaurant:</p>
  
  <pre><code>public class Restaurant
  {
      public int ID { get; set; }
      public string Name { get; set; }
      public string City { get; set; }
      public string Country { get; set; }
      public float AverageRating { get; set; }
      public DateTime Data { get; set; }
      public virtual ICollection&lt;Review&gt; Reviews { get; set; }
  }
  </code></pre>
  
  <p>Review model:</p>
  
  <pre><code>public class Review
  {
      public int ID { get; set; }
      public int Rating { get; set; }
      public string Body { get; set; }
      public string ReviewerName { get; set; }
      public int RestaurantID { get; set; }
      public DateTime Data { get; set; }
  }
  </code></pre>
  
  <p>API Post:</p>
  
  <pre><code>public IActionResult Post(ReviewDTO r)
  {
      try
      {
          if (!ModelState.IsValid)
              return BadRequest("Not a valid model");
          else
          {
              Review review = _mapper.Map&lt;ReviewDTO, Review&gt;(r);
              //review.Restaurant = _restaurantAppService.Find(review.RestaurantID);
              _reviewAppService.Add(review);
  
              //_restaurantAppService.Find(review.RestaurantID).Reviews.Add(review);
              _restaurantAppService.Average(_restaurantAppService.Find(review.RestaurantID));
              return Ok();
          }
      }
      catch (Exception ex)
      {
          //Log.Log.Error("Api error - Review - Post::" + ex.Message + "::" + ex.InnerException.Message + "::" + ex.InnerException.InnerException.Message);
          throw new Exception("Error Api - Review - Post \n", ex);
      }
  }
  </code></pre>
  
  <p>And finally the repository:</p>
  
  <pre><code>public void Add(TEntity e)
  {
      try
      {
          db.Set&lt;TEntity&gt;().Add(e);
          db.SaveChanges();
      }
      catch (Exception ex)
      {
          throw new Exception("Error in Infra.DATA - Add" + ex.Message, ex);
      }
  }
  
  public IEnumerable&lt;TEntity&gt; All()
  {
      try
      {
          return db.Set&lt;TEntity&gt;().AsNoTracking().ToList();
      }
      catch (Exception ex)
      {
          throw new Exception("Error in Infra.DATA - All", ex);
      }
  }
  </code></pre>
  
  <p>So here is the issue:</p>
  
  <ul>
  <li>The review is created   </li>
  <li>The API call the application methods </li>
  <li>The entity class inserts the review into the database</li>
  <li>The api call the application method to insert the review into the restaurant list'reviews'</li>
  <li>The review is inserted successfully, debugging I can see that the restaurant is updated in the database with the review inserted</li>
  <li>The controller sends back the restaurant to see the details of the restaurant, where its reviews are listed, but in this
  step, the reviews are missing and it is set to null.</li>
  </ul>
  
  <p>I can edit, delete and create a restaurant and a review, but I can't storage them with the restaurant.</p>
  
  <p>I have done this very same project in framework instead of core and had no problem with it, anyone knows why is this happening?</p>