如何将数据从一种形式放入另一种形式的列表框中

Question

Okay so I'm adapting a C# program to an asp program and I have a main form which contains a list box and another which adds new information to the list box. I can fill in the 2nd form and hold values in Application["getData"]; but when I go to the other page I need to run the following code.

public void AddGig()
    {
        AddGigForm frm = new AddGigForm();

        if (Application["getData"] != null)
        {
            Application["saveData"] = Application["getData"];
            gigList.addGig(frm.GetData());


            UpdateListbox();
        }

I run into problems at gigList.addGig as it goes back to the method GetData() on the 2nd form. I just have no idea what else to use.

GetData method:

public GigOpportunity GetData()
    {


            Application["GetData"] = new GigOpportunity
                (txtId.Text, gigDate.SelectedDate, txtVenue.Text, txtGenre.Text,
                Convert.ToDouble(txtCost.Text), Convert.ToInt32(txtCapacity.Text), chkHeadliner.Checked, txtMainAct.Text, chkEngineer.Checked);


            return new GigOpportunity(txtId.Text, gigDate.SelectedDate, txtVenue.Text, txtGenre.Text, Convert.ToDouble(txtCost.Text), Convert.ToInt32(txtCapacity.Text), chkHeadliner.Checked, txtMainAct.Text, chkEngineer.Checked);
    }

addGig method:

public void addGig(GigOpportunity gigOpportunity)
    {
        //Make sure a gig with this id does not already exist

        foreach (GigOpportunity g in gigList)
        {
            if (g.GigId == gigOpportunity.GigId)
            {
                throw new DuplicateIdException();
            }
        }

        gigList.Add(gigOpportunity);
    }

Answer 1

I understand now your problem. You musn't think like in windows form. You declared those method inside other form. When you call it by assigning a new Form object you will not get the value inside as they have been disposed after you change the page.

So in your case:

  if (Application["getData"] != null)
  {
        Application["saveData"] = Application["getData"];
        gigList.addGig((GigOpportunity)Application["getData"]);


        UpdateListbox();
  }

But I will suggest you to use Session object instead of Application object. You can read more about it here

So you have to do like this:

  if (Session["getData"] != null)
  {
        Session["saveData"] = Session["getData"];
        gigList.addGig((GigOpportunity)Session["getData"]);


        UpdateListbox();
  }

You don't need to create the second form object AddGigForm and you must be sure to call your method GetData in the form where is it declared to assign your Session.