子关系在父 object 中不可用

Question

I have the following method that returns a list of factory cars.

It works, but the ordering is wrong.

CarEngines can have an orderId and I want to order by that.

Looking at other answers on here, I see that you can't do an order by inside the query and you have to do it afterwards.

The problem is, I can't access CarEngines as you can see below:

public async Task<ActionResult<CountryList>> GetCountryCarObject(Guid countryID)
{
    var factoryCars = await _context.CountryList
        .Include(n => n.CarList).ThenInclude(l => l.CarEngines)
        .Include(n => n.CarList).ThenInclude(l => l.CarOptions)
        .SingleOrDefaultAsync(c => c.CountryId == countryID);

    factoryCars.CarList.CarEngines  <== CarEngines doesn't show up in CarList object

    return factoryCars;
}

It is telling me that CarList doesn't contain a definition for CarEngines.

But it is in my CarList model, I have it defined like so:

public CarList()
{
    CarEngines = new HashSet<CarEngines>();
}

public virtual ICollection<CarEngines> CarEngines { get; set; }

Here are the two models:

public partial class CarList
{
    public CarList()
    {
        CarEngines = new HashSet<CarEngines>();
        CarOptions = new HashSet<CarOptions>();
    }

    public string CarId { get; set; }
    public string CarMake { get; set; }
    public string CarModel { get; set; }
    public Guid? CarCountryId { get; set; }

    public virtual ICollection<CarEngines> CarEngines { get; set; }
    public ICollection<CarOptions> CarOptions { get; set; }
}


public partial class CountryList
{
    public CountryList()
    {
        CarList = new HashSet<CarList>();
    }

    [Key]
    public Guid CountryId { get; set; }
    public string CountryName { get; set; }
    public string CountryLocation { get; set; }
    public string CountryDesc { get; set; }

    public virtual ICollection<CarList> CarList { get; set; }

}

So I'm not sure it doesn't see it.

Is there a way to get this to work?

Thanks!

Answer 1

Ok so the fact that there is something called CarList but is not a List is super confusing but moving on....

The issue is that CarList is a List. So use something like factoryCars.CarList.Select( x=>x.CarEngines) . Also rename that to var country instead of var factoryCars since you return a single country and not a list of cars.

Also rename your variables and classes this confusion was probably caused by this. For example instead of having ICollection<CarList> CarList you can rename it into ICollection<Car> Cars so right now from the name you can easilly understand there are multiple cars (thus its a collection) which includes the object Car