199. How to prevent a form from submitting twice - Part 1?

Problem

Suppose you have set up a form and you want to prevent the user from submitting the form twice as shown below. There are two methods to accomplish this. This article shows the first method.

How to prevent a form from submitting twice - Part 1?


Solution

  • In the first method, when the user clicks on the submit button the first time, we make that button inactive to prevent any further clicks.
  • It might be obvious to some, but in case you're looking for the method that "turns off" a button, it's GtkWidget::set_sensitive(false).

Sample Code

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<?php
$window = new GtkWindow();
$window->set_size_request(400, 240);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());

// display title
$title = new GtkLabel("Prevent a form from submitting twice\n".
"Part 1 - make the button inactive after first click");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 40);
$title->set_justify(Gtk::JUSTIFY_CENTER);
$alignment = new GtkAlignment(0.5, 0, 0, 0);
$alignment->add($title);
$vbox->pack_start($alignment, 0, 0);
$vbox->pack_start(new GtkLabel(), 0, 0);

$fields = array('Item number', 'Item Description', 'Unit price', 'Quantity');
$field_size = array(120, 200, 80, 80);
$entry = array(); // to store the text entries

$table = new GtkTable();
display_table($table, $fields, $field_size); // display the table
$vbox->pack_start($table);

function display_table($table, $fields, $field_size) {
    global $entry;
    $row = 0;
    foreach ($fields as $field) {
        $label = new GtkLabel("  $field: ");
        $alignment = new GtkAlignment(1, .5, 0, 0);
        $alignment->add($label);
        $table->attach($alignment, 0, 1, $row, $row+1, Gtk::FILL, Gtk::SHRINK, 0, 0);

        $entry[$row] = new GtkEntry();
        $alignment = new GtkAlignment(0, .5, 0, 0);
        $alignment->add($entry[$row]);
        $entry[$row]->set_size_request($field_size[$row], -1);
        $table->attach($alignment, 1, 2, $row, $row+1);
        ++$row;
    }
}

// create a submit button
$button = new GtkButton('Submit');
$button->set_size_request(60, 28);
$button->connect('clicked', 'on_click');
$row = count($fields);
$alignment = new GtkAlignment(0, 0.5, 0, 0);
$alignment->add($button);
$table->attach($alignment, 1, 2, $row, $row+1);

$window->show_all();
Gtk::main();

function on_click($button) {
    global $fields, $entry;
    $i=0;
    foreach($fields as $field) {
        echo "$field: ".$entry[$i]->get_text()."\n";
        ++$i;
    }
    $button->set_sensitive(false); // note 1
}

?>

Output

As shown above.

 

Explanation

The above example is based on How to align GtkEntry fields - Part 2?

What's new here:

  1. Turn off the button!

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