Create table in SQLite with generic class 'Quantity' as a picker - ERROR not a valid type for SQLite DB - sqlite

Question

Morning All,
xamarin forms - populate picker in MVVM from SQLite DB issue
So...Ive used the following post
https://www.c-sharpcorner.com/article/populate-picker-using-mvvm/
to help me include a populated picker using MVVM in my project, using a picker to allowing the user to select a 'Quantity' to order for each product (which all works fine as its populated from code, but now refactoring to load from SQLite..please see current code below)..
//ProductModel
public class ProductModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private int _ProductId;
private string _BrandName;
public ObservableCollection<Quantity> _ListQuantites;
private Quantity _selectedQuantity;
//ETC have removed the other properties for sake of this Q
//Constructor
public ProductModel()
{
//Subscription
this.PropertyChanged += OnPropertyChanged;
}
[PrimaryKey, AutoIncrement]
public int ProductId
{
get { return _ProductId; }
set
{
if (_ProductId == value) return;
_ProductId = value;
OnPropertyChanged();
}
}
public ObservableCollection<Quantity> ListQuantites
{
get
{
return _ListQuantites;
}
set
{
_ListQuantites = value;
OnPropertyChanged();
}
}
public Quantity SelectedQuantity
{
get
{
return _selectedQuantity;
}
set
{
if (value == null)
{
_selectedQuantity = _selectedQuantity;
}
else
{
_selectedQuantity = value;
OnPropertyChanged();
}
}
}
//OnPropertyChanged
private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == nameof(SelectedQuantity))
{
//test quantity amount
}
}
// [NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Up Until now I was populating the ProductModel with its picker, from the constructor of the ProductViewModel page with:
WineList = new ObservableCollection<ProductModel>();
WineList.Add(new ProductModel { ProductId = 1, BrandName = "Mc guigans", Grape = "Red", ListQuantites = List_Quantites, Image = "W.png", Description = "Fruity Flav", Size="700ml", Price = 10.00M, SubTotalForItem = 0.00M, Genre = "Wine" });
//etc...and so on
//then
List_Quantites = PickerService.GetQuantitiesForProductPage();
//Picker service
public static ObservableCollection<QuantityModel> GetQuantitiesForProductPage()
{
var quantities = new ObservableCollection<QuantityModel>()
{
new QuantityModel() {Key=1, Value="0"},
new QuantityModel() {Key=2, Value="1"},
new QuantityModel() {Key=3, Value="2"},
new QuantityModel() {Key=4, Value="3"}
//etc
};
return quantities;
}
//XAML
<Picker Grid.Column="3" Grid.Row="0" Title=" " VerticalOptions="Center" x:Name="productPicker" VerticalTextAlignment="Center" HorizontalOptions="EndAndExpand" ItemsSource="{Binding ListQuantites}" ItemDisplayBinding="{Binding Value}" SelectedIndexChanged="QuantityChanged" SelectedItem ="{Binding SelectedQuantity}"/>
So...yeah as I said all works fine and dandy...But now I would like to load the ProductModel list from a table in SQLite....I have already used SQLite basic CRUD operations to create, load, view, update, edit...etc for orders made...so this is also working...the problem I seem to be having is creating the table, it is failing when I try to create an entry in the table with 'Quantity'....obviously...so I have changed the code...change 'Quantity' to object, then the plan being to populate this on the VM...but this also didnt work...
found another post relating to this:
https://forums.xamarin.com/discussion/2546/create-table-in-xamarin-throws-exception-because-of-generic-list
So 'Quantity' class is not a valid type for SQLite DB value...but turns out neither is object...has anyone idea for a work around for this...or some advice on how to refactor to resolve this?
any help or point in the right direction is appreciated thank Y