Question

I have two models Garden and Flower

public class Garden
{
    public int Id { get; set; }
    public string Name { get; set; } // Default value: Garden #[Id]

    // Location.
    public int LocationX { get; set; }
    public int LocationY { get; set; }

    // Flowers.
    public virtual List<Flower> Flowers { get; set; }
}

public class Flower
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Color { get; set; }
    public double Height { get; set; }

    public DateTime LastWatered { get; set; }
    public DateTime Planted { get; set; }
}

public class DataContext : DbContext
{
    public DbSet<Garden> Gardens { get; set; }
}

And now, I need to select a flower by Id. I got to this, but I’m not sure that’s the good way. How should I do it? Do you have any articles about that?

var garden = _db.Gardens.Where(g => g.Id == gardenId).SingleOrDefault();
var flower = garden.Flowers.Where(f => f.Id == flowerId).SingleOrDefault();

Answer 1

I would suggest this:

 var garden = _db.Gardens.SingleOrDefault(g => g.Id == gardenId);

 Flower flower = null;

 if (garden != null)
 {
     flower = garden.Flowers.SingleOrDefault(f => f.Id == flowerId);
 }     

Instead of using Where first and SingleOrDefault afterwards just use SingleOrDefault.

EDIT

As @JoachimIsaksson suggested, I have added a null reference check for garden to avoid the possible NullReferenceException.