Question

I’ve created custom list:

public class BList : IEnumerable<Position>
{
        private List<Position> positions = new List<BPosition>();
        public void Add(Position p)
        { this.positions.Add(p); }
        ...
}

Than this list is member of the class Invoice:

public class Invoice : Record
{
        public BList Positions = null;
        public Invoice()
            : base()
        {
            Init();
            this.Positions = new BList(this);
        }
        ...
}

Now in form constructor I populate collection of the Invoices and add positions to BList:

foreach(Invoice invoice in this.invoices)
{
    // Load position for current invoice from the database
    List<Position> positionsTmp = new List<Position>();
    DB.LoadRecordset(positionsTmp, "id_invoice=3");
    // and add to invoice positions items
    positionsTmp.ToList().ForEach(p => invoice.Positions.Add(p));
}

List of the positions in each invoice is populated correctly.
But when I use list this.invoices in other functions in this same class each invoice has Position list empty (Count = 0). It looks like positions are added localy and when application leaves the constructor all previously added positions do BList are cleared.
How I can populate BList for each invoice to they was available in entire class ?

Thanks

Answer 1

If the name of your class is “Invoice”, then the constructor must be called “Invoice” as well.

In the constructor of BList (I assume) you are intializing a local list called “positionsTmp”. Instead add the positions directly to “Positions”.