CODEWITHSUNDEEP
c#winformsproperties
lorenzoid
lorenzoid

Reputation: 1832

Passing objects from parent-form to child-form via properties (Winforms)

I know how to pass an object from parent-form to sub-form using constructors.

For example in the parent form, I do this:

WithdrawDialog dlg = new WithdrawDialog(cust.Accounts);

Child form:

public WithdrawDialog(BankAccountCollection accounts)
{
    InitializeComponent();
    PopulateComboBox(accounts);
}

// populate comboBox with accounts
private void PopulateComboBox(BankAccountCollection accounts)
{
    foreach (BankAccount b in accounts)
    {
        comboBoxAccount.Items.Add(b);
    }
}

I'm still trying to get the hang of Properties... How would I use properties instead of overloaded constructors to do this?

Upvotes: 0

Views: 2326

Answers (4)

rfmodulator
rfmodulator

Reputation: 3738

While it is possible to do this with a public property, it wouldn't be recommended. A method is more suited for this because you need to perform logic to populate the control.

If you're just trying to get it out of your constructor, make PopulateComboBox public or internal (if the parent and child are in the same assembly), and think about changing the name to something more descriptive, like "PopulateBankAccounts" or "AddBankAccounts".

Then you can do something like this in the parent form:

using (WithdrawDialog dlg = new WithdrawDialog())
{
    dlg.AddBankAccounts(cust.Accounts)
    DialogResult result = dlg.ShowDialog();

    if (result == DialogResult.Ok)
    {
        //etc...
    }
}

Upvotes: 0

david.s
david.s

Reputation: 11403

In the parent form:

WithdrawDialog dlg = new WithdrawDialog();
dlg.Accounts = cust.Accounts;

Child form:

public class WithdrawDialog
{
    private BankAccountCollection _accounts;

    public WithdrawDialog()
    {
        InitializeComponent();
    }

    public BankAccountCollection Accounts
    {
        get { return _accounts; }
        set { _accounts = value; PopulateComboBox(_accounts); }
    }

    // populate comboBox with accounts
    private void PopulateComboBox(BankAccountCollection accounts)
    {
        foreach (BankAccount b in accounts)
        {
            comboBoxAccount.Items.Add(b);
        }
    }
}

Upvotes: 0

Boaz
Boaz

Reputation: 4669

in WithdrawDialog do:

public WithdrawDialog()
{
    InitializeComponent();
}

public BankAccountCollection Accounts{
    set{
        PopulateComboBox(value);
    }
}

in the calling form do:

WithdrawDialog dlg = new WithdrawDialog{Accounts=cust.Accounts};

(this curly braces invoke the Object Initializer)

Upvotes: 0

competent_tech
competent_tech

Reputation: 44931

Here you go:

WithdrawDialog dlg = new WithdrawDialog();
dlg.accounts = cust.Accounts;
dlg.Show();

public WithdrawDialog()
{
    InitializeComponent();
}

private BankAccountCollection m_Accounts;
public BankAccountCollection accounts {
   get {
      return m_Accounts;
   }
   set {
      m_Accounts = value;
      PopulateComboBox(m_Accounts);
   }
}

// populate comboBox with accounts
private void PopulateComboBox(BankAccountCollection accounts)
{
    foreach (BankAccount b in accounts)
    {
        comboBoxAccount.Items.Add(b);
    }
}

Alternatively, PopupComboBox could be rewritten to use the accounts property:

// populate comboBox with accounts
private void PopulateComboBox()
{
    foreach (BankAccount b in this.accounts)
    {
        comboBoxAccount.Items.Add(b);
    }
}

Upvotes: 3

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