How to Allow NULL Foreign Keys with SQLite-net-extensions - sqlite-net

Question

I'm trying to add a nullable foreign key mapping but it doesn't work. I know the database allows nulls, since I can insert a new record with a null foreign key when using Datagrip. I only get the error when trying to insert from a Xamarin.Forms project building for Android(SQLite.SQLiteException: 'Constraint')
My classes look like:
public class Item
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string Name { get; set; }
...
[ForeignKey(typeof(Location))]
public int LocationId { get; set; }
[ManyToOne]
public Location Location { get; set; }
}
public class Location
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string Name { get; set; }
...
[OneToMany]
public List<Item> Items { get; set; }
}
And my inserts like
//This will no work
var todoItem = new Item()
{
Name = "Test item " + DateTime.Now.TimeOfDay.ToString(),
Description = "Desc",
Location = null // I tried with and without this line
};
await App.Database.SaveItemAsync(todoItem);
//This will work
var todoItem = new Item()
{
Name = "Test item " + DateTime.Now.TimeOfDay.ToString(),
Description = "Desc",
LocationId = 1
};
await App.Database.SaveItemAsync(todoItem);
Any idea what I'm doing wrong? Thanks

Answer 1

Apparently the library needs that the id field to be nullable, so instead of
[ForeignKey(typeof(Location))]
public int LocationId { get; set; }
I should use
[ForeignKey(typeof(Location))]
public int? LocationId { get; set; }
PS: In my case just building the project didn't took the changes on to effect, I only could see the result after Rebuild the project..(I'm new with Xamarin, probably I have something misconfigured...I hope)