AJAX request on the frontend always returns 0 if user is not admin

For the plugin i wrote, AJAX request on the frontend works properly if i am admin, but the same thing doesn’t work when i try it as normal user, it always returns 0.

This is plugin’s core php file where i am doing all the enqueue and localize stuff:

require_once ( plugin_dir_path(__FILE__) . 'like-user-request.php' );

function lr_enqueue_ui_scripts() {
    wp_enqueue_script( 'core-likeranker-js', plugins_url( 'js/like.js', __FILE__ ), array( 'jquery', 'jquery-ui-datepicker' ), false, true );
    wp_enqueue_style( 'jquery-style', 'http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.2/themes/smoothness/jquery-ui.css' );
    wp_localize_script( 'core-likeranker-js', 'my_ajax_object', array( 'ajax_url' => admin_url('admin-ajax.php'), 'security' => wp_create_nonce('user-like') ) );
}

add_action( 'wp_enqueue_scripts', 'lr_enqueue_ui_scripts');

This is javascript file

jQuery(document).ready(function($){

var state = $('#post-like-count').data('user-state');

$('.like-button').on('click', function(){
    var count = $('#post-like-count').data('id');
    var postId = $('#post-like-count').data('post-id');
    state == 1 ? count++ : count--;

    $.ajax({
        url: my_ajax_object.ajax_url,
        type: 'POST',
        dataType: 'json',
        data: {
            action: 'save_like',
            likeCount: count,
            id: postId,
            userState: state,
            security: my_ajax_object.security
        },
        success: function(response) {
            if(response.success === true){
                $('#post-like-count').html(count + ' Likes');
                $('#post-like-count').data('id', count);
                if(state == 1){
                    state = 2;
                    $('.like-button').html('Dislike');
                }
                else {
                    state = 1;
                    $('.like-button').html('Like !');
                }
                $('#post-like-count').data('user-state', state);
            }
        },
        error:function(error) {
            $('.like-box').after('Error');
        }
    });
  })
});

Php file that i handle the AJAX request

<?php
function lr_save_like_request() {
    if ( ! check_ajax_referer( 'user-like', 'security' ) ) {
        wp_send_json_error( 'Invalid Nonce !' );
    }

    $count = $_POST['likeCount'];
    $postId = $_POST['id'];
    $ip;

    if ( ! empty( $_SERVER['HTTP_CLIENT_IP'] ) ) {
        //check ip from share internet
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } elseif ( ! empty( $_SERVER['HTTP_X_FORWARDED_FOR'] ) ) {
        //to check ip is pass from proxy
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }

    $voters_ip = get_post_meta( $postId, '_voters_ip', false );

    $flag = empty( $voters_ip ) ? 1 : 0;

    if( $_POST['userState'] == 1 ) {
        if( $flag == 1 ) {
            $voters_ip_buffer = $voters_ip;
            $voters_ip_buffer[] = $ip;
        } else {
            $voters_ip_buffer = $voters_ip[0];
            $voters_ip_buffer[] = $ip;
        }
    } else {
        $voters_ip_buffer = $voters_ip[0];
        for ( $i=0; $i < count($voters_ip_buffer); $i++ ) {
            if( $ip == $voters_ip_buffer[$i] ) {
                unset( $voters_ip_buffer );
            }
        }
    }

    if( ! update_post_meta( $postId, '_Like', $count ) ) {
        add_post_meta ( $postId, '_Like', $count, true );
    }

    if( ! update_post_meta( $postId, '_voters_ip', $voters_ip_buffer ) ) {
        add_post_meta ( $postId, '_voters_ip', $voters_ip_buffer, true );
    }

    wp_send_json_success( array(
        'state' => $_POST['userState']
    ));

    wp_die();
}

add_action( 'wp_ajax_save_like', 'lr_save_like_request' );

As mmm didn’t post an answer but just wrote a comment, here is the answer:

As the documentation for wp_ajax states in its notes, the hook only fires for logged in users.
If you want to use an ajax call on the frontend for users that are not logged in, you have to use the wp_ajax_nopriv hook.

So instead of

add_action( 'wp_ajax_save_like', 'lr_save_like_request' );

you have to write

add_action( 'wp_ajax_nopriv_save_like', 'lr_save_like_request' );

Thats all, the functionality of the two hooks is exactly the same, the only difference is that one fires only for logged in users and the other one for everybody.