Untested Pseudo-code examples, which you can expand to resolve the issues:
function get_the_user_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'];
}
return apply_filters( 'get_the_user_ip', $ip );
}
Then, you can store all data in a single post_meta field, you just need to structure your array correctly.
array(
'like' => array(
'ip1', 'ip2', 'ip3', 'etc'
),
'dislike' => array(
'ip4', 'ip5', 'ip6', 'etc'
)
)
This way you can create a few helper functions ( or, better a class with some getter and setter methods ) to reference when loading the UI and when saving data.
function get_like_count( $type="like" ) {
// get post meta ##
$array = get_post_meta( get_the_ID(), 'post_meta_field' );
// @todo -- validate it is an array and the requested key exists ##
// return count ##
return count( $array[ $type ] );
}
function set_like_count( $type="like" ) {
// get post meta ##
$array = get_post_meta( get_the_ID(), 'post_meta_field' );
// @todo -- validate it is an array and the requested key exists ##
// update count for post ##
$array[ $type ][] = get_the_user_ip();
// save ##
update_post_meta( get_the_ID(), 'post_meta_field', $array );
}
/** check if the user IP is already stored for this post */
function has_liked() {
// get post meta ##
$array = get_post_meta( get_the_ID(), 'post_meta_field' );
// @todo -- validate it is an array and the requested key exists ##
// search the array for the IP value
// this might need to search each array key if you want to know what action the user took ##
return in_array( get_the_user_ip(), $array );
}