I'm trying to build a form in the backoffice to save some data in a custom table. The form is a list of checkbox, in witch the value is linked to a selected user.

So you have to select a user in a dropdown list, hit filter and then an ajax call is made to load the real form with checked value when checked before. This parts works well, I have my pre checked values. On submit, the form needs to save the selected user_id and also the checked checkboxs in order to save each checked value with the appropriate user_id.

The troubles comes when I try to save the form. First problem is when I do die(var_dump($_POST)); at the beginning of my save function, I get the selected user_id as expected but I don't get all of the checked checkboxs and instead I get only the last checked value (exemple I check 4 checkboxs I'm expecting 4 Ids in $_Post, but i Only get the last one). Weird thing is that if I look at the payload in network tabs I see all of my data but somehow they dont endup in my $_Post.

Second trouble is that before saving I need to check wich value is already in the DB so I can save new ones and delete the uncheked values. How can I do that ? I've tried a few things but not sure how to tackle this. And lastly my saving loop does not work, Wordpress always return "WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 1] INSERT INTO wp_mytable( store_id,data_id) VALUES;" Any one can help me figure this out ?

EDIT Thanks to alexcool88 I now have all of my checked checkboxs Id in $_Post

Now I'm still wondering how to save these, and at the same time remove from db the unchecked id if they were checked before. Should I delete every entries with the corrersponding store_id ? Or should I compare which is saved dans add remove data depending onc hecked values ?


 <div class="wrap">

     <div class="brand">
         <div class="brand_dropdown">
             <p class="brand_text">Form </p>

             <form method="POST"  action="<?php echo site_url() ?>/wp-admin/admin-ajax.php">
                 <div class="select">
                     <input type="hidden" name="action" value="filterBrandRestrict">

                     <select name="retailerfilterwatch">
                         <option value="">Select retailer...</option>

                            $posts = new WP_Query(array('post_type' => 'retailer'));
                            while ($posts->have_posts()) : $posts->the_post();
                                wp_reset_postdata(); ?>
                             <option id="selection" value="<?php echo get_the_ID(); ?>"><?php echo get_the_title(); ?></option>

                         <?php endwhile; ?>

                     <button id="filter_btn">Apply filter</button>

         <div class="brand__checkbox" id="responseBrand">


add_action('wp_ajax_filterBrandRestrict', 'filter_brand_retailer');
add_action('wp_ajax_nopriv_filterBrandRestrict', 'filter_brand_retailer');

function filter_brand_retailer()

    $store_id = $_POST['retailerfilter'];
    global $wpdb;

    $query = $wpdb->prepare("SELECT data_id FROM `mytable` WHERE `store_id` = '%d'", $store_id);

    $results = $wpdb->get_results($query, OBJECT_K);

    $Brand = new WP_Query(array('post_type' => 'watch_brand'));
    if ($Brand->have_posts()) : ?>
        <div class="control-group legend_brand">
            <form method="post" action="<?php echo site_url() ?>/wp-admin/admin-post.php" contentType: false,>
                <!-- Store id -->
                <input type="hidden" name="store_ids" value="<?php echo $store_id ?>">
                <input type="hidden" name="action" value="saveBrand">
                <!--  loop on brand to create checkboxes -->
                <?php while ($watchBrand->have_posts()) : $watchBrand->the_post(); ?>
                    <label class="control control-checkbox">
                        <?php echo get_the_title(); ?>

                        <input name="data_ids" value="<?php echo get_the_ID(); ?>" <?= isset($results[get_the_ID()]->data_id)  == get_the_ID() ? 'checked' : '' ?> type="checkbox" />

                        <div class="control_indicator"></div>
                <?php endwhile; ?>
                <div class="submit_default">
                    <button name="Submit" class="submit_button" type="submit">Envoyer</button>
    else :
        echo 'No posts found';



1 Answer 1


You must define the checkbox to store array in order to get all the selected values. Change your input name from "data-ids" to "data-ids[]".

<input name="data_ids[]" value="<?php echo get_the_ID(); ?>" <?= isset($results[get_the_ID()]->data_id)  == get_the_ID() ? 'checked' : '' ?> type="checkbox" />
  • Hi, axcool88, thanks that solved my first problem, now I get every checked checkboxes Id. How would you save the checkboxes id ? Since there won't be more than 20 checkboxes, I tought about deleting every entries with the user_id and then insert the checkboxes values, might be faster to execute for the server rather than checking wich is checked and update accordingliny and delete the unckecd value
    – Francis
    Commented Apr 28, 2023 at 10:04
  • Hi @Francis, your thought is right, deleting all entries and saving the entire checked values again is the easiest method.
    – axcool88
    Commented May 3, 2023 at 14:40

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