Script called by AJAX from WordPress plugin isn’t getting $wpdb

I’m writing a WordPress plugin and want to use ajax to submit data. When using ajax to submit a form in the admin panel, I get this error:

Fatal error: Call to a member function insert() on a non-object in
/home1/crave/public_html/wp-content/plugins/MiniCMS/add_contenttype.php
on line 13

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Here’s the script being called. Error line is annotated.

<?php
global $wpdb;

$name = $_POST["name"];
$id = '1';
$text_inputs = $_POST["text_inputs"];
$paragraph_inputs = $_POST["paragraph_inputs"];
$map_inputs = $_POST["map_inputs"];
$file_inputs = $_POST["file_inputs"];

$contentTypeTable = $wpdb->prefix . "minicms_content_type";

//This is line 13, the problem child:
$wpdb->insert( $contentTypeTable, array(
    'name' => $name,
    'id' => $id,
    'text_inputs' => $text_inputs,
    'paragraph_inputs' => $paragraph_inputs,
    'map_inputs' => $map_inputs,
    'file_inputs' => $file_inputs
));
?>

Does anyone know why I’m not getting $wpdb to work?

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1 comment

  1. You need to use ajax in WordPress way.

    From WordPress Doc:

    First add some javascript that will trigger the AJAX request:

    <?php
    add_action( 'admin_footer', 'my_action_javascript' );
    
    function my_action_javascript() {
    ?>
    <script type="text/javascript" >
    jQuery(document).ready(function($) {
    
        var data = {
            action: 'my_action',
            whatever: 1234
        };
    
        // since 2.8 ajaxurl is always defined in the admin header and points to admin-ajax.php
        $.post(ajaxurl, data, function(response) {
            alert('Got this from the server: ' + response);
        });
    });
    </script>
    <?php
    }
    

    Then, set up a PHP function that will handle that request:

    add_action('wp_ajax_my_action', 'my_action_callback');
    
    function my_action_callback() {
        global $wpdb; // this is how you get access to the database
    
        $whatever = intval( $_POST['whatever'] );
    
        $whatever += 10;
    
            echo $whatever;
    
        die(); // this is required to return a proper result
    }
    

    Reference:
    1. http://codex.wordpress.org/AJAX_in_Plugins
    2. http://wp.tutsplus.com/articles/getting-started-with-ajax-wordpress-pagination/