Viewmodel not updating model after add or insert to list - mvvm

Question

I'm fairly new to MVVM and Entity framework and I've hit a problem trying to add new records to my SQL database through MVVM. Below is the first and last part of my viewmodel which loads from my entity framework and this is working fine.
internal class MainWindowViewModel : INotifyPropertyChanged, IDisposable
{
public event PropertyChangedEventHandler PropertyChanged;
private TEAMSEntities ctx = new TEAMSEntities();
public MainWindowViewModel()
{
FillSales();
}
public void AddASale()
{
Tbl_Sales newsale = new Tbl_Sales();
newsale.SALEID = "2018...";
newsale.SALE = "....";
newsale.SALEDESC = "....";
newsale.START = Convert.ToDateTime("12/04/2018");
newsale.SESSIONS = 2;
newsale.DAYS = 2;
newsale.LOTS = 100;
newsale.FIRSTLOT = 1;
newsale.LASTLOT = 100;
Sales.Add(newsale);
SaveChanges();
}
#region Sale
private void FillSales()
{
var q = (from a in ctx.Tbl_Sales
select a).ToList();
this.Sales = q;
}
private List<Tbl_Sales> _sales;
public List<Tbl_Sales> Sales
{
get
{
return _sales;
}
set
{
_sales = value;
NotifyPropertyChanged();
}
}
private Tbl_Sales _selectedSale;
public Tbl_Sales SelectedSale
{
get
{
return _selectedSale;
}
set
{
_selectedSale = value;
NotifyPropertyChanged();
}
}
#endregion Sale
.
.
.
.
public void SaveChanges()
{
ctx.SaveChanges();
}
private void NotifyPropertyChanged([CallerMemberName] String
propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public void Dispose()
{
((IDisposable)ctx).Dispose();
}
}
When I make changes to existing data in the view bound to the viewmodel and call the SaveChanges method in the viewmodel it saves the change back to the SQL database every time. If I call the AddASale method it adds that sale to the list but doesn't refresh the UI control bound to Sales and doesn't pass the newly created sale back to the SQL DB. Through debugging I can see the set being called in the Sales property when the LINQ code runs but it doesn't fire when I add a new sale through the AddASale code which is probably why the UI isn't updating...?
Can anyone offer any guidance as to what I'm doing wrong?
Thanks in advance.
Alex

Answer 1

First, add your new entity in your context and save it like this :
Tbl_Sales newsale = new Tbl_Sales
{
SALEID = "2018...",
SALE = "....",
SALEDESC = "....",
START = Convert.ToDateTime("12/04/2018"),
SESSIONS = 2,
DAYS = 2,
LOTS = 100,
FIRSTLOT = 1,
LASTLOT = 100
};
ctx.Tbl_Sales.Add(newsale);
SaveChanges();
after that, I think you have to refresh your list manually :
FillSales();
Here, a link to MSDN
Hope I helped you