Passing JSON data from WP Query into AJAX causing NULL errors

The question:

I am currently using a WP_Query that’ll trigger from an AJAX call when a button is pressed. The post meta fields lat lng will be used as location data for a google map. The query outputs fine without AJAX but cannot seem to get it to return the results with it.

The response I receive – [{name: "", lng: null, lat: null}, {name: "", lng: null, lat: null}]

Now I believe the error is when transforming the results into JSON at json_encode stage, but not too sure? Any help would be great, fairly new to AJAX!

Function.php

<?php
//Search Function

function ek_search(){
    $args = array(
        'orderby' => 'date',
        'order' => $_POST['date'], 
        'post_type' => 'property',
        'posts_per_page' => 20,
        'date_query' => array(
        array(
            'after' => $_POST['property_added']
        ),
    ),
    );

$query = new WP_Query( $args ); 
$posts = $query->get_posts();   

foreach( $posts as $post ) {
     $locations[] = array(
       "name" => get_the_title(),
       "lng" => get_field('loc_lng'),
       "lat" => get_field('loc_lat')
     );
 }     

$location = json_encode($locations);

echo $location;

die();

}

add_action( 'wp_ajax_nopriv_ek_search', 'ek_search' );
add_action( 'wp_ajax_ek_search', 'ek_search' );

Form

<form id="filter">

<button>Search</button>
<input type="hidden" name="action" value="ek_search">

</form>

JS

jQuery(function($){
    $('#filter').submit(function(){
        var filter = $('#filter');
        var ajaxurl = '<?php echo admin_url("admin-ajax.php", null); ?>';
        data = { action: "ek_search"};
        $.ajax({
            url: ajaxurl,
            data:data,
            type: 'post',
            dataType: 'json',
            success: function(response) {
            console.log(response);  
            }

        });
        return false;
    });
});

The Solutions:

Below are the methods you can try. The first solution is probably the best. Try others if the first one doesn’t work. Senior developers aren’t just copying/pasting – they read the methods carefully & apply them wisely to each case.

Method 1

Admin-AJAX is not optimized for JSON. If you need your answer to be in JSON, use the REST-API instead. This API generates JSON response by default.

All you have to do is to register a rest route, and access the URL:

add_action( 'rest_api_init', function () {
    //Path to REST route and the callback function
    register_rest_route( 'scopeak/v2', '/my_request/', array(
            'methods' => 'POST', 
            'callback' => 'my_json_response' 
    ) );
});

Now, the callback function:

function my_json_response(){
    $args = array(
        'orderby' => 'date',
        'order' => $_POST['date'], 
        'post_type' => 'property',
        'posts_per_page' => 20,
        'date_query' => array(
            array(
                'after' => $_POST['property_added']
            ),
        ),
    );

    $query = new WP_Query( $args ); 
    if($query->have_posts()){
        while($query->have_posts()){
        $query->the_post();
            $locations[]['name'] = get_the_title();
            $locations[]['lat'] = get_field('loc_lng');
            $locations[]['lng'] = get_field('loc_lat');
        }
    }
    //Return the data
    return $locations;
}

Now, you can get your JSON response by visiting the following URL:

wp-json/scopeak/v2/my_json_response/

For testing purposes, you can change POST method to GET and directly access this URL. If you get a response, then change it back to POST and work on your javascript.

That’s all.

Method 2

First of all, how are you getting the $_POST variables? you have to pass them in your data object on your ajax call. Example:

jQuery(function($){
$('#filter').submit(function(){
    var filter = $('#filter');
    var ajaxurl = '<?php echo admin_url("admin-ajax.php", null); ?>';
    data = { action: 'ek_search', date: date, property_added: property};
    $.ajax({
        url: ajaxurl,
        data:data,
        type: 'post',
        dataType: 'json',
        success: function(response) {
        console.log(response);  
        }

    });
    return false;
  });
});

See this Article for reference.

Method 3

Firstly, I am really sorry for responding a little late.

Second, you need to get the values of your form by using the serialize method, Please check the below example.

<form id="filter">

<input type="button" name="smt" value="Submit" id="smt" />
<input type="hidden" name="action" value="ek_search">

</form>


<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
var form=$("#filter");
$("#smt").click(function(){
$.ajax({
    type:"POST",
    url:form.attr("action"),
    data:form.serialize(),
    success: function(response){
        console.log(response);  
    }
});
});
});
</script>


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

Leave a Comment