关联实体在LINQPad中有效，但在运行时为null

Question

Let's assume I have some car related entities. A Vehicle class and a VehicleType class.

public class Vehicle
{
    public int Id {get; set;}
    public string Name {get; set}
    public int VehicleTypeId {get; set;}
    public virtual VehicleType VehicleType {get; set;}
}

public class VehicleType
{
    public int Id {get; set;}
    public string VehicleTypeName {get; set}
    public ICollection<Vehicle> Vehicles {get; set;}
    public ICollection<Price> Prices {get; set;}
}

public class Price
{
    public int Id {get; set;}
    public int Price {get; set;}
    public int VehicleTypeId {get; set;}
    public virtual VehicleType VehicleType {get; set;}
}

The VehicleType table serves as a relationship table to both the Vehicle table and the Price table. I am trying to use LINQ to get at the Price for a given Vehicle based upon it's VehicleType ...

var myVehicle = dbContext.Vehicles.FirstOrDefault(v => v.Id == 1234);
var myVehiclePrice = myVehicle.VehicleType.Prices.Select(p => p.Price);

Now when using LINQPad this query works well when I use my database as the source. I get back the Price as expected. However, when using this inside Visual Studio an exception is thrown on ..

var myVehiclePrice = myVehicle.VehicleType.Prices.Select(p => p.Price);

The exception is that VehicleType is null. I know there is data there, I am just not sure why VehicleType is showing as null .

And yes I am using the same connection string in my web.config and LINQPad.

EDIT: I should note that when using LINQPad I was using C# Expressions rather than C# Statements.

Solution : I was able to get it working. In the end, in order to get the prices, I had to include BOTH the VehicleType and Price entities in the Include statement.

var myVehcilePrice = myVehicle.Include("VehicleType.Prices").Single(v => v.Id == 1234).VehicleType.Prices

Note that you want to include the association name in the Include statement. Thanks to TheGeekYouNeed for the help on Include.

Answer 1

var myVehicle = dbContext.Vehicles.Where(v => v.Id == 1234).Include("VehicleType").FirstOrDefault();