How to use AJAX form submit in WordPress

Question

I have custom page template with a form with 2 dropdown and 1 input submit. When the user submit the form, the result will be displayed, this is working properly. But I have a problem, the browser is reload when fetching the data in the database.

I want to use AJAX to prevent reloading of page. I saw some article about Ajax WordPress, but I cannot work it correctly.

Anyone can please help me out? How to do with AJAX? How can I call the custom PHP file in the AJAX?

AJAX (functions.php)

    function ajax_enqueue_sl(){
    wp_enqueue_script('ajax_load_sl', get_template_directory_uri().'/js/alternate-dropdown.js', array('jquery'));
    wp_localize_script('ajax_load_sl', 'ajax_object', array('ajax_url' => admin_url( 'admin-ajax.php')));
}
add_action('wp_enqueue_scripts', ajax_enqueue_sl);

add_action('init', 'registerFormAction');
function registerFormAction(){
    // To handle the form data we will have to register ajax action. 
    add_action('wp_ajax_nopriv_submitAjaxForm','submitAjaxForm_callback');
    add_action('wp_ajax_submitAjaxForm','submitAjaxForm_callback');
}

function submitAjaxForm_callback(){
    global $wpdb;
    if(is_page(9208)){
        //ROCK ON!
        if (isset($_POST['store_list']) && $_POST['store_list'] != 'Select by Store'){
        $store_list = $_POST['store_list'];
        $stores= $wpdb->get_results($wpdb->prepare("SELECT street FROM tablename WHERE stores= '" . $store_list . "' AND col IN ('test') ORDER BY street ASC", OBJECT));
        foreach ($stores as $record_s){
            echo '<div class="records">';
            echo '<div><span class="icons-tabbed-store icon-icon-stores">' . $record_s->street . '</span></div>';
            echo '</div>';
        }
    } elseif (isset($_POST['mall_list']) && $_POST['mall_list'] != 'Select by Mall'){
        $mall_list = $_POST['mall_list'];
        $street = $wpdb->get_results($wpdb->prepare("SELECT stores FROM tablename WHERE street= '" . $street_list . "' AND col IN ('test') ORDER BY stores ASC", OBJECT));
        foreach ($street as $record_m){
            echo '<div class="records">';
            echo '<div><span class="icons-tabbed-store icon-icon-stores">' . $record_m->stores . '</span></div>';
            echo '</div>';
        }
    }
    }
    wp_die();
}

PHP w/ HTML (test.php)

$results_street = $wpdb->get_results('SELECT DISTINCT street FROM tablename WHERE code IN ("test1") ORDER BY street ASC', OBJECT);
$results_stores = $wpdb->get_results('SELECT DISTINCT stores FROM tablename WHERE code IN ("test2") ORDER BY stores ASC', OBJECT);

<form action='' method='post' name='myform' id="myform">
<div class="pos-div">
<select name="street_list" id="filterbystreet">
    <option name="default" class="filter_by" value="Select by">Select by</option>
    <?php
    foreach($results_street as $option){
        if(isset($_POST['street_list']) && $_POST['street_list'] == $option->street)
            echo '<option name="street_list" class="filter_by" selected value="'. $option->street .'">'. $option->street .'</option>';
        else    
         echo '<option name="street_list" class="filter_by" value="'. $option->street .'">'. $option->street .'</option>';
     };
    ?>
</select>
</div>
<span class="or">or</span>
<div class="pos-div">
<select name="store_list" id="filterby">
    <option name="default" class="filter_by" value="Select by">Select by</option>
    <?php 
    foreach($results_stores as $option){
        if(isset($_POST['store_list']) && $_POST['store_list'] == $option->stores)
            echo '<option name="store_list" class="filter_by" selected value="'. $option->stores .'">'. $option->stores .'</option>';
        else    
         echo '<option name="store_list" class="filter_by" value="'. $option->stores .'">'. $option->stores .'</option>';
     };
    ?>
</select>
</div>
<input type="submit" value="List all partner stores" class="pos-submit"/>
</form>

if (isset($_POST['store_list']) && $_POST['store_list'] != 'Select by Store'){
        $store_list = $_POST['store_list'];
        $stores= $wpdb->get_results($wpdb->prepare("SELECT street FROM tablename WHERE stores= '" . $store_list . "' AND code IN ('test3') ORDER BY street ASC", OBJECT));
        foreach ($stores as $record_s){
            echo '<div class="records">';
            echo '<div><span>' . $record_s->street. '</span></div>';
            echo '</div>';
        }
    } elseif (isset($_POST['street_list']) && $_POST['street_list'] != 'Select by'){
    $street_list = $_POST['street_list'];
    $streets = $wpdb->get_results($wpdb->prepare("SELECT street FROM tablename WHERE street_list= '" . $street_list. "' AND code IN ('test3') ORDER BY stores ASC", OBJECT));
    foreach ($streets as $record_m){
        echo '<div class="records">';
        echo '<div><span>' . $record_m->stores . '</span></div>';
        echo '</div>';
    }
}

ajax_js.js

    jQuery(document).ready(function($){
    //$('#myform').submit(ajaxFormSubmit);

    $('#filterbystreet').change(function(){
        $('#filterbystore').prop('selectedIndex','Select by Store');
    });

    $('#filterbystore').change(function(){
        $('#filterbystreet').prop('selectedIndex','Select by');
    });

    jQuery('.pos-submit').on('click',function(e){ 
        e.preventDefault(); 
        var myform = jQuery('#myform').serialize(); 

        jQuery.ajax({ 
            type:"POST", 
            // Get the admin ajax url which we have passed through wp_localize_script(). 
            url: ajax_object.ajax_url, 
            action: "submitAjaxForm", 
            data: myform, 
            success:function(data){ 
                jQuery(".records").html(data); 
                console.log(data);
            } 
        }); 
    });
});

Answer 1

Follow the steps below :

• Change the input type submit to div. (so that page doesn't gets refreshed when form is submitted).
• Provide some ID to button/div.
• Write onlcick jquery for that ID, as below : (explained below #2)
• Now "select_options" will be the name of your ajax hook example :
• Create the definition for the call back function "my_action_callback" (explained #3)
• function my_action_callback(){ echo 'testing';}, then "testing" will the result in the output string of jQuery function.

2 :

$('#ID_OF_DIV').click(function(){
    var admin_ajax_url = $('#admin_ajax_url').val();
    $.post(
          admin_ajax_url, 
          {
              'action': 'select_options',
              'name1':   value1,
              'name2':   value2,
              .... so on,
          }, 
          function(output){
          //output will be the response from the ajax code code.
          });
});

3

add_action( 'wp_ajax_select_options', 'my_action_callback' );
add_action( 'wp_ajax_nopriv_select_options', 'my_action_callback' );

Answer 2

Do not submit the form on ajax call. You can use like this.

    jQuery('#filterbymall').change(function(){

        jQuery('#filterbystore').prop('selectedIndex','Select by Store');
        ajaxSubmit();        

    });

    jQuery('#filterbystore').change(function(){

        jQuery('#filterbystreet').prop('selectedIndex','Select by');        
        ajaxSubmit();      

    });


function ajaxSubmit(){
    var myform= jQuery("'#myform").serialize();
    jQuery.ajax({
        type:"POST",
        url: "/wp-admin/admin-ajax.php",
        data: myform,
        success:function(data){
            jQuery(".records").html(data);
        }
    });
    return false;
}

and change this

  <input type="submit" value="List all partner stores" class="pos-submit"/>

to

  <input type="button" value="List all partner stores" class="pos-submit"/>

input type submit to button