C# Winform event handler

Question

I have 2 constructors in my class:

public partial class Fiche_Ordre : Le_MainForm
    {
         public Fiche_Ordre()
              {
                  InitializeComponent();           
                  Constuct_Page();            
              }

              public Fiche_Ordre(string OrderID): this()
              {


                    Pers_Ordre oPersOrdr = oOrder_BL.Get_OrdreOne_BL(ClientID, Convert.ToInt32(OrderID), false);

                textEdit_RefExpred.Text = oPersOrdr.RefExpd;
                lookUpEdit_Agence.EditValue = oPersOrdr.Agence;
                lookUpEdit_Transport.EditValue = oPersOrdr.Transporteur;

                lookUpEdit_Dest.EditValue = oPersOrdr.DestId;
    ..................

              }


              public void Constuct_Page()
              {
                  try
                  {
                      ClientID = Program.Le_ClientID;
                      ....

              #region LookUpEdidt Destinataire

                   lookUpEdit_Dest.Properties.DataSource = Auxiliaire_BL.FillCombo_BL(false, ClientID).Tables["ComboFill"];
                   lookUpEdit_Dest.Properties.ValueMember = "CODE_DEST";
                   lookUpEdit_Dest.Properties.DisplayMember = "CODE_DEST";
                   LookUpColumnInfoCollection coll_Dest = lookUpEdit_Dest.Properties.Columns;
                   // A column to display the ProductID field's values.
                   coll_Dest.Add(new LookUpColumnInfo("CODE_DEST", 0, "Code Destinataire"));
                   // A column to display the ProductName field's values.
                   coll_Dest.Add(new LookUpColumnInfo("RS_NOM", 0, "Raison Social"));
                   //  Set column widths according to their contents and resize the popup, if required.   
                   lookUpEdit_Dest.Properties.BestFitMode = BestFitMode.BestFitResizePopup;
                   // Enable auto completion search mode.
                   lookUpEdit_Dest.Properties.SearchMode = SearchMode.AutoComplete;
                   // Specify the column against which to perform the search.
                   lookUpEdit_Dest.Properties.AutoSearchColumnIndex = 1;
                   lookUpEdit_Dest.EditValueChanged += new EventHandler(lookUpEdit_Dest_EditValueChanged);
              #endregion
        ...
        }

It is strange, because when I use public Fiche_Ordre() it does not fire new EventHandler(lookUpEdit_Dest_EditValueChanged); ; but when I use public Fiche_Ordre(string OrderID) , it does fire the event handler.

Is this normal or not?

the first constuctor it call from Main form

 public partial class Le_MainForm : DevExpress.XtraEditors.XtraForm
    {
        public Le_MainForm()
        { 
            InitializeComponent();

            this.Name = "MainUSER";

            if (Program.IsFA) barButtonItem_OrdList.Visibility = DevExpress.XtraBars.BarItemVisibility.Never;


        }

 private void barButtonItem_CreatOrdreAller_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e)
        {
            Close_AllForm();
            Program.AllerRetour = "Ordre Aller";
            Fiche_Ordre f_Fiche = new Fiche_Ordre();

            f_Fiche.Show();
        }

and the second constructor i call it from

public partial class Liste_Ordres : Le_MainForm
    {

     private void Liste_DobleClic(object sender, EventArgs e)
            {
                try
                {
                    Program.OrderId = gridView_Liste_Ordres.GetFocusedRowCellValue("NO_ORDRE").ToString();
                    this.Hide();
                    Fiche_Ordre f_Fiche = new Fiche_Ordre(gridView_Liste_Ordres.GetFocusedRowCellValue("NO_ORDRE").ToString());
                    f_Fiche.Show();
                }
                catch (Exception excThrown)
                {
                    MessageBox.Show(excThrown.Message);
                }
            }

Thank you in advance.

PS: the first constructor is just to create the NEW blank page, and the second constructor is to create NOT NEW (Edit page), so i passed the id and fill all control (textbox, memo, etc...)

Answer 1

The EditValueChanged handles is wired in the very last line of Constuct_Page . Therefore it fires only for changes after Constuct_Page . Is it changed in the .................. part of the code? It does sound like an over-simplified speculation, but it's worth double-checking anyway...

Besides, may I suggest you another improvement:

public Fiche_Ordre(string OrderID) : this.Fiche_Ordre()
{
  // invokes the other constructor first, so they're guaranteed
  // do be equivalent in the first part

  Pers_Ordre oPersOrdr = oOrder_BL.Get_OrdreOne_BL(ClientID,
    Convert.ToInt32(OrderID), false);

  // ...
}

Answer 2

当您想绑定事件处理程序时，放下断点并查看lookUpEdit_Dest，我认为此var不会初始化，因此您需要从第二个构造函数添加到第一个构造函数。

Answer 3

instead create Constuct_Page(); just put in Form_Load()