I am creating a basic ASP.NET Core Web API which contains a list of countries/locations/places of interest.

I have created all the methods for location which are a child of the country object and everything is working as expected.

However I am trying to create a method for adding a point of interest (child of the location object) but it just doesn’t save anything to the database, even though the code is laid out identically to how I am doing it for the location.

Here is my controller:

var finalPlaceOfInterest = mapper.Map<PlaceOfInterest>(placeOfInterestForCreation);

await repository.AddPlaceOfInterestAsync(locationId, finalPlaceOfInterest);
await repository.SaveChangesAsync();

Repository code

public async Task AddPlaceOfInterestAsync(int locationId, PlaceOfInterest placeOfInterest) 
{
    var location = await GetLocationAsync(locationId);

    if (location != null) 
    {
        location.PlacesOfInterest.Add(placeOfInterest);
    }
}

public async Task<bool> SaveChangesAsync() 
{
    return (await context.SaveChangesAsync() >= 0);
}

My PlaceOfInterest entity class is defined like this:

public class PlaceOfInterest 
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Required]
    public string Name { get; set; } = string.Empty;
    
    public string Description { get; set; } = string.Empty;

    [ForeignKey("LocationId")]
    public Location? Location { get; set; }

    public int LocationId { get; set; }
}

After calling repository.SaveChangesAsync, the finalPlaceOfInterest object should get populated with its ID and the Location & LocationID properties, but they are not being set and nothing is being persisted to the database.

I have identical code for creating a Location, but with the Country as its parent, and it works correctly and is saved. After calling the SaveChangesAsync method, the ID, Country & CountryID properties are populated.

What am I missing? Starting to go a bit mad here as I can’t figure out why this won’t work. I’ve added migrations and updated my database & all the tables & columns are correct.