BindingList Listchanged事件未触发 [英] BindingList Listchanged event not fired

问题描述

我的应用程序中包含以下代码.但是Listchanged事件未按预期触发.我有一个对象预订".我是从frmMain调用的.你能告诉我问题吗?

i have the following code in my application. But Listchanged event is not fired as expected. I have an object "Booking". I am calling this from frmMain. Would you please tell me the problem ??

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;
    }

}

}

我从这里调用此代码

I am calling this code from here

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);
        }
    }

推荐答案

您希望在哪里触发ListChanged?

您正在覆盖FillEntity中的CashLoans，因此在构造函数中分配给它的所有内容都消失了.您可能要在FillEntity中附加事件处理程序.

Where would you expect the ListChanged to be fired?

You are overwriting CashLoans in FillEntity, so whatever you assign to it in the constructor is gone. You probably want to attach the event handler in FillEntity.

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