Question

I’m using the Code First approach and have the following Model:

public class Person
{
    public int ID {get; set;}
    public string Name {get; set;}

    public int CurrentStationID {get; set;}
    public virtual Station CurrentStation {get; set;}

    public int CurrentTransportationID {get; set;}
    public virtual Transportation CurrentTransporation {get; set;}
}

And the following code in my controller:

Models.Person model = myDBContext.Persons
                        .Include("CurrentStation")
                        .Include("CurrentTransportation")
                        .Where(p => p.ID == 1)
                        .FirstOrDefault();

“model” is going to be NULL even though a row with (1, “Testname”, 0, 0) exists in the DB table “persons”.

The above generates a SQL-statement with [...] INNER JOIN stations AS [...] LEFT JOIN transportations [...]. It always does an INNER JOIN for the first navigational property, for all my models, regardless what the underlying table/type is or in which order I specify them, it’s always the first Include().

I do not want an INNER JOIN but a LEFT JOIN on all of them, since “CurrentStation” is not required to be in the database.

Why does EF do this??? I don’t understand but I want to understand. I have not specified a [Required]-attribute on any of the properties, yet it behaves as if I did.

Unfortunately there’s no [Optional]-attribute and doing a “HasOptional()” via the OnModelCreate-override is not an option for me.

Answer 1

If I am not mistaken, in order to allow a property to be optional or in the database sense, nullable, you must make the property nullable. So in the case of your CurrentStationId property you can try declaring it as follows:

 public int? CurrentStationId {get;set;}

UPDATE
This post may be of some help for your situation.