C#•8mo ago

listbox SelectedIndexChanged on load?

Hello, I'm newer to C# and I'm making a windows form where a listbox lists customers and populates txtboxes to the right if the index changes, er is supposed to because it does it on load. Where would this be caused to fill in even when the form loads and the index hasn't changed?

26 Replies

RdZoidOP•8mo ago

I've verified this is the only space those get populated because if I comment that section out nothing loads there

SpReeD•8mo ago

In unselected state the index is -1, 0 is the first item selected, since this is zero-based-index. Is there an item selected? -> Yes -> Your condition will result in true

RdZoidOP•8mo ago

how can I have it not start selected/ at 0?

SpReeD•8mo ago

It depends on how you fill the ListBox items

RdZoidOP•8mo ago

it's being filled from an XML file

SpReeD•8mo ago

No, I mean is it filled by setting the DataSource or manipulating the Items list

RdZoidOP•8mo ago

data source

RdZoidOP•8mo ago

if I comment it out here they disappear

RdZoidOP•8mo ago

this may clarify

SpReeD•8mo ago

Setting the DataSource on a ListBox will make an automatic selection on the first item 0. This is somewhat a ListBox bug, you could workaround by manipulating the Items list or workaround bool when changing the DataSource.

RdZoidOP•8mo ago

That's weird, doesn't make it seem very indexchanged-ey, can you think of an easy way to make sure the txtboxes on the right side stay blank unless something's actually selected?

SpReeD•8mo ago

Yes, as written before.

RdZoidOP•8mo ago

it might be wacky but could I just "" the textboxes after the refresh() is called in form load?

SpReeD•8mo ago

private bool dataSourceChange;

private void Main_Load(object sender, EventArgs e)
{
    this.dataSourceChange = true;
    this.listBox1.DataSource = new string[] { "foo", "bar" };
    this.dataSourceChange = false;
}

private void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (this.dataSourceChange)
    {
        this.listBox1.SelectedIndex = -1;
        return;
    }

    //more of your code here
}

private bool dataSourceChange;

private void Main_Load(object sender, EventArgs e)
{
    this.dataSourceChange = true;
    this.listBox1.DataSource = new string[] { "foo", "bar" };
    this.dataSourceChange = false;
}

private void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (this.dataSourceChange)
    {
        this.listBox1.SelectedIndex = -1;
        return;
    }

    //more of your code here
}

Or just do AddRange(customers), since it seems it's an Array/List.

RdZoidOP•8mo ago

hmmm the bool thing didn't seem to work

SpReeD•8mo ago

It does, try stepping through the code.

RdZoidOP•8mo ago

I might just have inserted it incorrectly, how do you add code here?

SpReeD•8mo ago

$codegif

MODiX•8mo ago

https://cdn.discordapp.com/attachments/364492811489509376/892176158312001586/code.gif

RdZoidOP•8mo ago

public partial class frmBanking : Form
{
    List<Customer> customers;
    MySettings settings;
    private bool dataSourceChange;

    public frmBanking()
    {
        InitializeComponent();

    }

    private void frmBanking_Load(object sender, EventArgs e)
    {
        this.dataSourceChange = true;
        this.lbxCustomers.DataSource = new string[] { "foo", "bar" };
        this.dataSourceChange = false;

        try
        {
            

            settings = Program.Configuration.GetSection("MySettings").Get<MySettings>();

            this.Text = settings.Text;


            lblStatus.ForeColor = Color.Black;


            //customers = CustomerManager.Populate();
            customers = CustomerManager.ReadXML(settings.CustomerXMLFilename);

            
            Refresh();
            


        }
        catch (Exception ex)
        {
            lblStatus.ForeColor = Color.Red;
            lblStatus.Text = ex.Message;
        }
    }

    private void Refresh()
    {
        lbxCustomers.DataSource = null;
        lbxCustomers.DataSource = customers;
        lbxCustomers.DisplayMember = "FullName";
        lbxCustomers.ValueMember = "Id";
        lblStatus.Text = $"{lbxCustomers.Items.Count} Customers loaded";
        lblStatus.ForeColor = Color.Blue;
    }

    

    private void lbxCustomers_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (this.dataSourceChange)
        {
            this.lbxCustomers.SelectedIndex = -1;
            return;
        }

        try
        {
            lblStatus.ForeColor = Color.Black;
            lblStatus.Text = string.Empty;


            if (lbxCustomers.SelectedIndex >= 0)
            {
                Customer customer = customers[lbxCustomers.SelectedIndex];

                txtFirstName.Text = customer.FirstName;
                txtLastName.Text = customer.LastName;
                txtSSN.Text = customer.SSN;
                txtId.Text = customer.Id.ToString();
                dtBirthDate.Text = customer.Birthdate.ToString();


                dgvDeposits.DataSource = null;
                dgvWithdrawals.DataSource = null;


            }

        }
        catch (Exception ex)
        {
            lblStatus.ForeColor = Color.Red;
            lblStatus.Text = ex.Message;
        }
    }

public partial class frmBanking : Form
{
    List<Customer> customers;
    MySettings settings;
    private bool dataSourceChange;

    public frmBanking()
    {
        InitializeComponent();

    }

    private void frmBanking_Load(object sender, EventArgs e)
    {
        this.dataSourceChange = true;
        this.lbxCustomers.DataSource = new string[] { "foo", "bar" };
        this.dataSourceChange = false;

        try
        {
            

            settings = Program.Configuration.GetSection("MySettings").Get<MySettings>();

            this.Text = settings.Text;


            lblStatus.ForeColor = Color.Black;


            //customers = CustomerManager.Populate();
            customers = CustomerManager.ReadXML(settings.CustomerXMLFilename);

            
            Refresh();
            


        }
        catch (Exception ex)
        {
            lblStatus.ForeColor = Color.Red;
            lblStatus.Text = ex.Message;
        }
    }

    private void Refresh()
    {
        lbxCustomers.DataSource = null;
        lbxCustomers.DataSource = customers;
        lbxCustomers.DisplayMember = "FullName";
        lbxCustomers.ValueMember = "Id";
        lblStatus.Text = $"{lbxCustomers.Items.Count} Customers loaded";
        lblStatus.ForeColor = Color.Blue;
    }

    

    private void lbxCustomers_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (this.dataSourceChange)
        {
            this.lbxCustomers.SelectedIndex = -1;
            return;
        }

        try
        {
            lblStatus.ForeColor = Color.Black;
            lblStatus.Text = string.Empty;


            if (lbxCustomers.SelectedIndex >= 0)
            {
                Customer customer = customers[lbxCustomers.SelectedIndex];

                txtFirstName.Text = customer.FirstName;
                txtLastName.Text = customer.LastName;
                txtSSN.Text = customer.SSN;
                txtId.Text = customer.Id.ToString();
                dtBirthDate.Text = customer.Birthdate.ToString();


                dgvDeposits.DataSource = null;
                dgvWithdrawals.DataSource = null;


            }

        }
        catch (Exception ex)
        {
            lblStatus.ForeColor = Color.Red;
            lblStatus.Text = ex.Message;
        }
    }

SpReeD•8mo ago

Your Refresh method lacks the bool set to true.

RdZoidOP•8mo ago

private void Refresh()
{
    lbxCustomers.DataSource = null;
    lbxCustomers.DataSource = customers;
    lbxCustomers.DisplayMember = "FullName";
    lbxCustomers.ValueMember = "Id";
    lblStatus.Text = $"{lbxCustomers.Items.Count} Customers loaded";
    lblStatus.ForeColor = Color.Blue;
    dataSourceChange = true;
}

private void Refresh()
{
    lbxCustomers.DataSource = null;
    lbxCustomers.DataSource = customers;
    lbxCustomers.DisplayMember = "FullName";
    lbxCustomers.ValueMember = "Id";
    lblStatus.Text = $"{lbxCustomers.Items.Count} Customers loaded";
    lblStatus.ForeColor = Color.Blue;
    dataSourceChange = true;
}

like that^?

SpReeD•8mo ago

private void Refresh()
    {
        dataSourceChange = true;
        lbxCustomers.DataSource = null;
        lbxCustomers.DataSource = customers;
        lbxCustomers.DisplayMember = "FullName";
        lbxCustomers.ValueMember = "Id";
        lblStatus.Text = $"{lbxCustomers.Items.Count} Customers loaded";
        lblStatus.ForeColor = Color.Blue;
        dataSourceChange = false;
    }

private void Refresh()
    {
        dataSourceChange = true;
        lbxCustomers.DataSource = null;
        lbxCustomers.DataSource = customers;
        lbxCustomers.DisplayMember = "FullName";
        lbxCustomers.ValueMember = "Id";
        lblStatus.Text = $"{lbxCustomers.Items.Count} Customers loaded";
        lblStatus.ForeColor = Color.Blue;
        dataSourceChange = false;
    }

RdZoidOP•8mo ago

holy shit that worked

SpReeD•8mo ago

You can delete the thingy in the Load method, this was for demo purpose. It's only important to set the bool to true before changing the DataSource. So the Event won't do it's logic.

RdZoidOP•8mo ago

ok nice, weird workaround but a workaround nonetheless thank you for your help!

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listbox SelectedIndexChanged on load?