How to get the array from PHP to JAVASCRIPT through AJAX and JSON?

Question

Can someone help me out? It seems like I get a string instead of an array. Once I pass the array, which is the result of a sql query, from PHP to Javascript through AJAX, I woul

Answer 1

In my case there was no need to use JSON.parse(data); again otherwise I used to get an error of "Unexpected token o in JSON at position 1 at " By only putting dataType: "json" is enough. I post my final code:

functions.php

add_action( 'wp_ajax_my_action', 'my_action' );
add_action( 'wp_ajax_nopriv_my_action', 'my_action' ); // This lines it's because we are using AJAX on the FrontEnd.

function my_action(){
    global $wpdb;

    $tablename = $wpdb->prefix . 'rg_lead_detail';
    $lead_id = $_POST['fieldvalue'];  // This variable will get the POST 'fieldvalue'
    $form_id = 21;

    $sql = "SELECT value FROM $tablename WHERE lead_id = %d AND form_id= %d";

    $results = $wpdb->get_results( $wpdb->prepare( $sql, $lead_id, $form_id ), ARRAY_A );

    echo json_encode($results);

    die();
} 

Javascript

(function($){
    $(document).ready(function() {
        $('#input_12_153').change(function (){
            if ($('#input_12_153').attr("value")== 'no-selection'){
                $('#input_12_48').val( '' );}
            else{
                var valor = $('#input_12_153').attr("value");
                jQuery.ajax({ // We use jQuery instead $ sign, because Wordpress convention.
                    url : '/optcat/wp-admin/admin-ajax.php', // This addres will redirect the query to the functions.php file, where we coded the function that we need.
                    type : 'POST',
                    data : {
                        action : 'my_action', 
                        fieldvalue : valor,
                    },
                    dataType:'json',
                    success: function(data) {
                        //var results = JSON.parse(data); // like this
                        $(data).each(function(i,val){
                            $.each(val,function(k,v){
                                alert(k+" : "+ v);     
                            });
                        });
                    }
                });
           }
       });
    });
})(jQuery);

Answer 2

Use JSON.parse() to turn the string from PHP into an array.

success: function(data) {
    var results = JSON.parse(data); // like this
    alert( data );
    //Here I would like to loop the array and get the values
}