add_action for publish_post doesn't work

Question

I'm working on a personal voting plugin, I don't intend to release it publicly because I'm still learning WP.

In general, you can vote posts "up" or "down". I have 2 tables, one collects IPs (to disallow voting multiple times) and another table named "post_votes" collects the number of votes for each post.

When I publish a new post its ID is stored in "post_votes" and I can update the "up", "down" for each post when people vote. This worked a few days ago. I did some modifications and I can't figure out why it's not working anymore..

This is the entire code so far.. I still need to implement some security precautions.

<?php
/*
Plugin Name: Vote Posts
*/

global $vote_posts_version;
$vote_posts_version = "1.0";

function vote_posts_install () {

   global $wpdb;
   global $vote_posts_version;

   $table_1 = $wpdb->prefix . "voter_ips";
   $table_2 = $wpdb->prefix . "vote_posts"; 

   if($wpdb->get_var("SHOW TABLES LIKE '$table_1 AND $table_2'") != $table_1 && $table_2) {

      $sql = "CREATE TABLE " . $table_1 . " (
      id bigint(20) NOT NULL AUTO_INCREMENT,
      vote_post_id bigint(20) NOT NULL,
      voter_ip varchar(100) NOT NULL,
      UNIQUE KEY id (id)
      );";

       $sql2 = "CREATE TABLE " . $table_2 . " (
      id bigint(20) NOT NULL AUTO_INCREMENT,
      vote_post_id bigint(20) NOT NULL,
      up int(11) NOT NULL,
      down int(11) NOT NULL,
      UNIQUE KEY id (id)
      );";

      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
      dbDelta($sql);
      dbDelta($sql2);

      add_option("vote_posts_version", $vote_posts_version);
   }        
}

register_activation_hook(__FILE__,'vote_posts_install');


//add and delete votes

function add_votes($post_ID)  {
global $wpdb;
   if (!($wpdb->get_row("SELECT vote_post_id FROM wp_vote_posts WHERE vote_post_id = $post_ID" ) ) ) { //if not exists add post ID to table
      $wpdb->insert( $wpdb->prefix . 'vote_posts', array( 'post_id' => $post_ID ) );
      return $post_ID;
   }
}
add_action ( 'publish_post', 'add_votes' ); //should trigger function on publish post

function delete_votes($post_ID)  {
    global $wpdb;
    $wpdb->query("DELETE FROM wp_vote_posts WHERE vote_post_id = $post_ID");
    return $post_ID;
}
add_action ( 'delete_post', 'delete_votes' ); //deletes row from post_votes table when a post is deleted from the WP panel

?>

It successfully creates the 2 tables but doesn't insert the post ID on action

Answer 1

No offense, but I think I'm agreeing with a commenter from your other question... You really need to read PHP, MySQL, and regular expression tutorials before you get into any of this. More importantly, you need to learn how to search a code base using regular expressions in your favorite editor, and understand the code you're reading.

Just to give you a few examples, this:

SHOW TABLES LIKE '$table_1 AND $table_2'

Is looking for a table called:

$wpdb->prefix . "voter_ips AND " . $wpdb->prefix . "vote_posts"

Bad, bad, bad...

Along the same lines, while your tables both have a not null unique key, which technically amounts to a primary key, the MySQL rewrite engine and optimizer don't treat those in the same way as primary keys, so you should declare it as such instead.

Then, there are the potential security holes:

SELECT vote_post_id FROM wp_vote_posts WHERE vote_post_id = $post_ID

... without casting $post_ID to (int) beforehand...

It also helps to var_dump() stuff if you're not using a PHP debugger. e.g. in your add_votes() call, how about this, to see what's happening?:

var_dump($post_ID);die;