Passing data using jQuery AJAX to PHP script

Question

HTML, AJAX and PHP included below. Before introducing AJAX, everything functions (form tags and PHP processing values removed from HTML below).

The drop-down (categories) is populated from a MySQL query. When the user selects an option, I want to pass the ID via ajax to a PHP script (index.php) to run a MySQL query to populate another drop-down (sub-categories).

The Chrome console log indicates that ajax is passing the ID correctly.

Firebug also shows it passing and that the URL is correct (index.php?business_category_id=ajax-passed value). If the GET variable is being passed, and my PHP script is looking for it, why is the script not responding? Why is it not receiving the value? I cannot echo it, so I know it's not being received.

The ajax script is in js/script.js, index.php (my controller) is in the root, and the page with the html (buy-a-biz.php) is in the root and included in the php script (see below).

If anyone can help, I'd appreciate it very much. I am new to using jQuery ajax.

HTML.

<select name="category" id="business-category">
    <option value="all_categories">Select category</option>
    <?php foreach ($categories as $category): ?>
        <option value="<?php htmlout($category['id']); ?>"><?php htmlout($category['name']); ?></option>
    <?php endforeach; ?>
</select>

AJAX. I experimented using $.get and $.post also.

$(document).ready(function(){

    $("#business-category").change(function(){
        var category_id = $(this).val();
        console.log(category_id);

        $.ajax({
            type: 'GET',
            url: 'index.php',
            data: { business_category_id: category_id },
            success: function(category_id){
                $("#result").html(category_id + ' submitted successfully!');
            }
        });
    });
});

PHP.

if(isset($_GET['business_category_id'])){ 

    $category_id = htmlspecialchars($_GET['business_category_id']);

    include 'includes/dbconnect.php';

    try {
        $sql = "SELECT * FROM sub_category
                WHERE category_id = :category_id";
        $s = $db->prepare($sql);
        $s->bindValue(":category_id", $category_id);
        $s->execute();

        while($row = $s->fetch(PDO::FETCH_ASSOC)){
            $sub_categories[] = array(
                'id' => $row['id'],
                'category_id' => $row['category_id'],
                'name' => $row['name']
            );
        }

        $sql2 = "SELECT * FROM category";
        $s2 = $db->prepare($sql2);
        $s2->execute();

        while($row  = $s2->fetch(PDO::FETCH_ASSOC)){
            $categories[] = array(
                'id' => $row['id'],
                'name' => $row['name'],
            );
        }   
    } 
    catch (PDOException $e) {
        $errMsg = "Error fetching data" . $e->getMessage();
        include 'error.html.php';
        exit();
    }

    include 'buy-a-biz.php';
    exit();

}

Possible duplicate of Passing POST data from Javascript(jquery) to php problems? — Sercan REYHANLI
– Sercan REYHANLI, Commented May 8, 2016 at 13:02
@IvanBarayev Thanks, but I was unable to develop a solution from this post. — JimB814
– JimB814, Commented May 8, 2016 at 13:33

wero · Accepted Answer · 2016-05-08 13:03:28Z

1

You are passing a done callback to $.ajax. You should either name this callback success

$.ajax({
    type: 'GET',
    url: 'index.php',
    data: { business_category_id: category_id },
    success: function(category_id){
            $("#result").html(category_id + ' submitted successfully!');
        }
    });

or invoke done on the promise returned by $.ajax:

$.ajax({
    type: 'GET',
    url: 'index.php',
    data: { business_category_id: category_id },
}).done(function(category_id) { 
    $("#result").html(category_id + ' submitted successfully!'); 
});

answered May 8, 2016 at 13:03

wero

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2 Comments

JimB814 Over a year ago

Thanks for your reply. Using success doesn't make it work. I experimented with success and done and learned that my message will display only if I use success. My php script @index.php is still not receiving the data.

JimB814 Over a year ago

I edited my code above to reflect using success. As written, this code generates an error. It displays the message if the category_id parameter is removed -- function() ... instead of function(category_id)....

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