Entity Framework Managing entity state Setting state Added of an object graph
Example
Setting the state of an object graph (a collection of related entities) to Added is different than setting a single entity as Added (see this example).
In the example, we store planets and their moons:
Class model
public class Planet
{
public Planet()
{
Moons = new HashSet<Moon>();
}
public int ID { get; set; }
public string Name { get; set; }
public ICollection<Moon> Moons { get; set; }
}
public class Moon
{
public int ID { get; set; }
public int PlanetID { get; set; }
public string Name { get; set; }
}
Context
public class PlanetDb : DbContext
{
public property DbSet<Planet> Planets { get; set; }
}
We use an instance of this context to add planets and their moons:
Example
var mars = new Planet { Name = "Mars" };
mars.Moons.Add(new Moon { Name = "Phobos" });
mars.Moons.Add(new Moon { Name = "Deimos" });
context.Planets.Add(mars);
Console.WriteLine(context.Entry(mars).State);
Console.WriteLine(context.Entry(mars.Moons.First()).State);
Output:
Added
Added
What we see here is that adding a Planet also sets the state of a moon to Added.
When setting an entity's state to Added, all entities in its navigation properties (properties that "navigate" to other entities, like Planet.Moons) are also marked as Added, unless they already are attached to the context.
