How can I populate a dynamic drop down box based on the selection of another drop down box?
I have a database table called category as shown below:
[Image of a database table named "category" with columns "id", "name", and "master"]
I am trying to do a dynamic drop down box and the index script is shown as:
[Code sample of the index script]
The update.php is shown as:
[Code sample of the update.php]
The 2nd drop down box is not showing the values dependent on the 1st drop down box as shown:
[Image of a form with two drop down boxes. The first drop down box has options for "Select one", "Category 1", and "Category 2". The second drop down box has only the option "----".]
Can someone help me please.
Answer:
To create a dynamic drop down box where the options in the second box depend on the selection in the first box, you can use the following approach:
-
Handle the change event of the first drop down box: Using jQuery, add a change event listener to the first drop down box. When the value of the first drop down box changes, this event will be triggered.
-
Send an AJAX request: In the event handler, make an AJAX request to a PHP file (e.g., update.php) that will return the options for the second drop down box based on the selected value of the first drop down box.
-
Handle the AJAX response: In the success callback of the AJAX request, parse the response data, which will contain the HTML code for the options to be added to the second drop down box.
-
Update the second drop down box: Use JavaScript to update the HTML of the second drop down box with the options generated from the response data.
-
Enable the second drop down box: Once the options are updated, enable the second drop down box for user selection.
Here is an example that demonstrates this approach:
tester.php:
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script>
$(function() {
$('#first_dropdown').change(function() {
var value = $(this).val();
$.ajax({
url: 'update.php',
method: 'POST',
data: { value: value },
success: function(response) {
$('#second_dropdown').html(response);
$('#second_dropdown').prop('disabled', false);
}
});
});
});
</script>
</head>
<body>
<select>update.php:
<?php
if (isset($_POST['value'])) {
$selectedValue = $_POST['value'];
$data = array();
// Here you would typically query your database to retrieve options based on the selected value.
if ($selectedValue == 'category1') {
$data[] = '<option value="option1">Option 1</option>';
$data[] = '<option value="option2">Option 2</option>';
} elseif ($selectedValue == 'category2') {
$data[] = '<option value="option3">Option 3</option>';
$data[] = '<option value="option4">Option 4</option>';
}
echo implode('', $data);
}
?>
By following this approach, you can create multi-level dynamic drop down boxes where the options in each drop down box are dependent on the selection made in the previous drop down box.
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