BindingList <> Non è stato attivato l'evento listchanged

Question

Ho il seguente codice nella mia domanda. Ma l'evento Listchanged non viene licenziato come previsto. Ho un oggetto "Booking". Lo chiamo da frmMain. Vorresti dirmi il problema ??

using System; 
using System.Collections.Generic; 
using System.Data; 
using System.Data.OleDb; 
using System.ComponentModel; 

namespace CustomObjects 
{ 
public class Booking:ObjectBase 
{ 

    private int pBookingNo=0; 
    private BindingList<Loans> pCashLoans = new BindingList<Loans>(); 

    public int BookingNo 
    { 
     get { return pBookingNo; } 
     set 
     { 
      if (!value.Equals(pBookingNo)) 
      { 
       pBookingNo = value; 
       PropertyHasChanged("BookingNo"); 
      } 
     } 
    } 

    public BindingList<Loans> CashLoans 
    { 
     get { return pCashLoans; } 
     set 
     { 
      pCashLoans = value; 
      //CalculateCashLoan(this,new System.ComponentModel.ListChangedEventArgs(ListChangedType.Reset,-1)); 
      PropertyHasChanged("CashLoans"); 
     } 
    } 

    private decimal pTakenCashLoan = 0; 
    public decimal TakenCashLoan 
    { 
     get { return pTakenCashLoan; } 
     set 
     { 
      pTakenCashLoan = value; 
      PropertyHasChanged("TakenCashLoan"); 
     } 
    } 

     public void CalculateCashLoan(object sender, ListChangedEventArgs args) 
    { 
     decimal total = 0; 
     foreach (Loans loan in pCashLoans) 
     { 
      total += loan.LoanAmount; 
     } 
     this.TakenCashLoan = total; 
    } 

    public Booking() 
    { 
     this.pCashLoans.ListChanged += this.CalculateCashLoan; 
    } 


    public static Booking FillEntity(OleDbDataReader Reader, OleDbConnection Connection) 
    { 
     Booking booking = new Booking(); 
     booking.BookingNo = (int)Reader["BookingNo"]; 

     booking.CashLoans = Loans.GetLoanList(booking.BookingNo, 1, Connection); 
     booking.MarkOld(); 
     return booking; 
    } 

    public static Booking GetEntity(int bookingNo, string ConnectionString) 
    { 
     Booking booking =new Booking(); 
     using (OleDbConnection Connection = new OleDbConnection(ConnectionString)) 
     { 
      string sqlSelect = "SELECT BookingNo FROM tblBooking WHERE BookingNo=" + bookingNo + ""; 
      using (OleDbCommand cmd = new OleDbCommand(sqlSelect, Connection)) 
      { 
       Connection.Open(); 
       OleDbDataReader bReader = cmd.ExecuteReader(); 
       if (bReader.HasRows) 
       { 
        bReader.Read(); 
        booking = FillEntity(bReader, Connection); 
       } 
       Connection.Close(); 

       if (!bReader.IsClosed) 
       { 
        bReader.Close(); 
       } 
      } 
     } 
     return booking; 
    } 

} 

} 

io chiamo questo codice da qui

private void frmMain_Load(object sender, EventArgs e) 
    { 
     AddDataBindings(); 
     cmbBookingType.DataSource = BookingType.GetSelectionList(ConnectionString.CreateConnectionStringForAccess("LOCAL", "2012")); 
    } 

    private Booking booking=new Booking(); 
    private void button1_Click(object sender, EventArgs e) 
    { 
     try 
     { 
      booking = Booking.GetEntity(1, ConnectionString.CreateConnectionStringForAccess("LOCAL", "2012")); 
      bsBooking.DataSource = booking; 
     } 
     catch (Exception Ex) 
     { 
      MessageBox.Show(Ex.Message); 
      MessageBox.Show(Ex.StackTrace); 
     } 
    } 

Answer 1

È perché si sta assegnando un nuovo BindingList istanza alla proprietà, invece di aggiungere e rimuovere elementi all'elenco esistente.

Provare a rendere la proprietà CashLoans di sola lettura, ad esempio rimuovere il set accessor e modificare il codice per cancellare l'elenco e aggiungere i nuovi elementi.