Question

I have an application that shows data from a MySQL table. Basically, my application consists of two forms: the main form, and a form for adding stuff to the database.

The main form shows all the entries in the database and relevant information. When the user wants to add a new entry to the database, a secondary form is opened that prompts for information. Once the information is filled out, the user presses a Submit button and the form closes. My problem is that when the secondary form closes, the listBox in the main form doesn’t update to reflect the newly-added entry.

Here is the code that is executed when the user submits the secondary form:

    private void closeWindow()
    {
        mainForm parent = new mainForm();
        parent.listParts.Refresh();
        this.Close();
    }

Is there a reason when I call the listBox to be refreshed, it doesn’t show my newly-added information? Perhaps I am calling something in the wrong order? Or does the Refresh() method not even work like that?

Any help would be appreciated! Alternatively, if you know of a better way to do this, I’d love to hear it!

Answer 1

The problem is that you’re refreshing the wrong form:

private void closeWindow()
{
    mainForm parent = new mainForm();
    parent.listParts.Refresh();
    this.Close();
}

Since you use: new mainForm(), you’re allocating a completely separate instance of the “mainForm”, and refreshing it’s content. This will not effect the existing, opened form.

I would recommend passing a reference to the mainForm to the constructor of the secondary form. It then would know which instance of mainForm it needs to use to call Refresh().