Getting null values in table (Entity Framework)

Question

I been working on a database in entity framework but encountering some problems.

I have a HotelChain model like this:

[Key]
public int HotelChainID { get; set; }
public string Name { get; set; }
public List<Hotel> Hotels { get; set; }

and a Hotel model:

[Key]
public int HotelID { get; set; }
public string Name { get; set; }
public List<Building> Buildings { get; set; }
public List<Amenities> Amenities { get; set; }

My HotelInitializer class:

        Repository.InsertHotel(new Hotel("Brussels", Repository.GetAllBuildings(), Repository.GetAllAmenities()));
        Repository.InsertHotel(new Hotel("Paris", Repository.GetAllBuildings(), Repository.GetAllAmenities()));
        Repository.InsertHotel(new Hotel("Berlin", Repository.GetAllBuildings(), Repository.GetAllAmenities()));
        Repository.InsertHotel(new Hotel("London", Repository.GetAllBuildings(), Repository.GetAllAmenities()));
        Repository.InsertHotel(new Hotel("Tenerife", Repository.GetAllBuildings(), Repository.GetAllAmenities()));
        Repository.InsertHotel(new Hotel("Amsterdam", Repository.GetAllBuildings(), Repository.GetAllAmenities()));
        Repository.InsertHotelChain(new HotelChain("Company Name", Repository.GetAllHotels()));

The problem is that there are double records in my Hotel table in the database, one time with the HotelChain_HotelChainID on null and one time with the HotelChain_HotelChainD on 1.

I'd like to achieve that only the records with the Hotelchain ID on 1 get added to the table. How could I achieve this?

These are my Repository methods:

    public static int InsertHotel(Hotel hotel)
    {
        HotelDbContext context = new HotelDbContext();
        context.Hotels.Add(hotel);
        context.SaveChanges();
        return hotel.HotelID;
    }
    public static List<Hotel> GetAllHotels()
    {
        HotelDbContext context = new HotelDbContext();
        return context.Hotels.ToList();
    }

Thank you for your time!

Seems like your Hotel class is missing a foreign key reference to HotelChain. In your initializer class you shouldn't be able to create hotels unless you have a hotel chain that exists. You should first add a foreign key reference first (as per your business logic - can a hotel exist in your system that's not part of a chain?). If you leave it out, you can still achieve what you're trying to do by first creating a hotel chain and then adding a list of hotels to that chain. — RizJa
– RizJa, Commented May 26, 2016 at 19:46
@RizJa For my business logic, a hotel should not be able to exist that is not part of a hotelchain, It is no longer listing null values now with this code: pastebin.com/Wc1W0nWV I also believe I will have to do tesame with the Buildings, Floors ... if I am correct? Thank you for the help! — josephzigler
– josephzigler, Commented May 27, 2016 at 7:46
Yes, the same logic would apply to Buildings and Floors.. a floor should only belong to a single building so you'd need a foreign key reference there as well. And not a problem.. you can either answer your own question and mark it as solved or I can put the comment above as an answer and you can accept that. — RizJa
– RizJa, Commented May 27, 2016 at 16:02
You can put the comment above and I will mark it as answered :) — josephzigler
– josephzigler, Commented May 27, 2016 at 16:07

RizJa · Accepted Answer · 2016-05-27 18:20:39Z

1

Seems like your Hotel class is missing a foreign key reference to HotelChain. In your initializer class you shouldn't be able to create hotels unless you have a hotel chain that exists. You should first add a foreign key reference first (as per your business logic - can a hotel exist in your system that's not part of a chain?). If you leave it out, you can still achieve what you're trying to do by first creating a hotel chain and then adding a list of hotels to that chain.

answered May 27, 2016 at 18:20

RizJa

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