C# using control created on form load in another control event

1
votes

my problem is as follows: I have 2 controls created on Form load, button and combobox, I also have event for button, but the event should be able to see the newly created combobox. When I try to call the combo by it's name it says that it don't exist in this context private void Form1_Load(object sender, EventArgs e) { Button przycisk = new Button(); przycisk.Name = "przycisk"; przycisk.Dock = DockStyle.Bottom; przycisk.Text = "Wybierz";

        ComboBox kombo = new ComboBox(); 
        kombo.Name = "kombo";
        kombo.Dock = DockStyle.Bottom;
        kombo.Items.Add("Przycisk");   
        kombo.Items.Add("Etykeita");
        kombo.Items.Add("Pole tekstowe");

        Controls.Add(kombo);  
        Controls.Add(przycisk);

        przycisk.Click += new EventHandler(przycisk_Click); 

    }

    private void przycisk_Click(object sender, EventArgs e)
    {

        kombo.Items.Add("Panel");  //just an example 
    }
}

Is there a way to make it working ?

2
c#scope

2 Answers

2
votes

Only controls which are in used in markup with runat="server" will be class variables on your page. They are actually defined in the designer file.

What you'll want to do is in the class add something like the following where you have a class variable, then assign kombo in your page-load function. Then, it will exist in your click event handler.

 // kombo is now scoped for use throughout this class
 ComboBox kombo = null;

 private void Form1_Load(object sender, EventArgs e)
    {
        Button przycisk = new Button(); 
        przycisk.Name = "przycisk";
        przycisk.Dock = DockStyle.Bottom;
        przycisk.Text = "Wybierz";

        // Assign to our kombo instance
        kombo = new ComboBox(); 
        kombo.Name = "kombo";
        kombo.Dock = DockStyle.Bottom;
        kombo.Items.Add("Przycisk");   
        kombo.Items.Add("Etykeita");
        kombo.Items.Add("Pole tekstowe");

        Controls.Add(kombo);  
        Controls.Add(przycisk);

        przycisk.Click += new EventHandler(przycisk_Click); 

    }

    private void przycisk_Click(object sender, EventArgs e)
    {
        // Using the kombo we created in form load, which is still referenced
        // in the class
        kombo.Items.Add("Panel");  //just an example 
    }
1
votes

You will have to use the FindControl() method to find the object first.

private void przycisk_Click(object sender, EventArgs e)
{
   ComboBox kombo = (ComboBox)FindControl("kombo");
   kombo.Items.Add("Panel");
}