Model association trouble with cakephp

Question

I was having trouble with a voting system that I'm trying to make in cakePHP (found here cakephp is querying extra column and I can't figure out why ) but I figured that out and now I'm having another issue.

I'm making a voting system, and the problem I'm having is that only one user can vote on a given post. For example, if user 1 votes on post 1, and then user 2 votes on post 1, user 2's vote will overwrite user 1's vote.

Here are my tables

Votes
id |   user_id   | vote

Posts
id | title | body | created | modified | user_id | vote_total

I'm having trouble setting up the associations

1. Users can vote on many posts

2. A post can have many votes, but only 1 per user

This is in my Users model

public $hasMany = array(
    'Posts' => array( 'className'  => 'Post'),
     'Votes' => array('className'  => 'Vote')
    );

This is in my Posts model

 public $hasMany = array( //there can be multiple votes of the same id (references post table)
    'Votes' => array('foreignKey' => 'id')
    );

I don't have a votes controller. It's done through a vote function on PostsController.php

Answer 1

public $hasMany = array( //there can be multiple votes of the same id (references post table)
    'Votes' => array('foreignKey' => 'id')
    );

is wrong. It should be:

 public $hasMany = array( //there can be multiple votes of the same id (references post table)
'Votes' => array('foreignKey' => 'post_id')
);

And so you have to add post_id in the Vote model.