Question

So I have two comboBoxes (comboBoxFromAccount and comboBoxToAccount). Each has the same datasource, which is AccountsList (a list of BankAccount objects that was passed from the parent form).

I would like to make it so that if an item is selected in one of the comboBoxes, it would no longer be selectable in the other. The way I’m trying to do this is by copying the list of BankAccounts from the comboBoxFromAccount to the comboBoxTo account, and removing the selected index of comboBoxFromAccount from the comboBoxToAccount.

I think I’m close, but what seems to happen is I have a blank comboBoxToAccount.

Here is my code:

    private BankAccountCollection accountsListTransferTo = new BankAccountCollection();

    // public property for passing collection data to the dialog
    public BankAccountCollection AccountsList
    {
        get { return accountsListTransferTo; }
        set { accountsListTransferTo = value; }
    }

    // Initial loading
    private void TransferFundsDialog_Load(object sender, EventArgs e)
    {
        textBoxAmount.Text = String.Empty;
        textBoxAmount.Select();
        comboBoxFromAccount.DataSource = AccountsList;

        accountsListTransferTo.AddRange(AccountsList); // Copy content
        accountsListTransferTo.Remove(comboBoxFromAccount.SelectedItem as BankAccount); // Remove item
        comboBoxToAccount.DataSource = accountsListTransferTo; // Data binding
    }

    private void comboBoxFromAccount_SelectedIndexChanged(object sender, EventArgs e)
    {
        accountsListTransferTo.Clear(); // Clear list, if you don't to it, AddRange will just add more items.
        accountsListTransferTo.AddRange(AccountsList); // Copy ALL accounts
        accountsListTransferTo.Remove(comboBoxFromAccount.SelectedItem as BankAccount); // Remove selected, so user cannot transfer to same account

        // Refresh data binding 
        comboBoxToAccount.DataSource = null;
        comboBoxToAccount.DataSource = accountsListTransferTo;

        // Select very first item in "TO" combobox
        comboBoxToAccount.SelectedIndex = 0;
    }

Help would be appreciated.

Answer 1

Try removing the line

comboBoxToAccount.DataSource = null;

I have a vague recollection about comboboxes having problems with this.