小花 ORM 数据透视表错误数据

我有用户、类别和帖子。用户有许多帖子，类别有很多帖子，帖子属于一个类别和一个用户。

我需要帮助显示具有正确帖子的正确用户。

表

categories{category_id, category_title}
posts{post_id, post_title}
users{user_id, user_title}
categories_posts{category_id, post_id}
users_posts{user_id, post_id}

模型

class Model_User extends ORM {
protected $_primary_key = 'user_id';
protected $_has_many = array(
    'posts'=> array(
        'model' => 'post',                
        'through' => 'users_posts',   
        'far_key' => 'post_id'        
    ),
  );
}
class Model_Category extends ORM {
    protected $_primary_key = 'category_id';
    protected $_has_many = array(
    'posts'=> array(
        'model' => 'post',                
        'through' => 'categories_posts',   
        'far_key' => 'post_id'           
    )
  );
}
class Model_Post extends ORM {
    protected $_primary_key = 'post_id';
    protected $_belongs_to = array(
    'categories'=> array(
        'model' => 'category',               
        'through' => 'categories_forums',  
        'far_key' => 'category_id'  
    ),
    'users'=> array(
        'model' => 'user',                
        'through' => 'users_posts',    
        'far_key' => 'user_id'   
    )
  );
}

显示

$categories = ORM::factory('category')->find_all(); 
foreach ($categories as $category) :
echo $category->category_title;
foreach ($category->posts->find_all() as $post) :
echo $post->post_title;
echo $post->users->user_title;
endforeach;
endforeach;

类别和帖子正确回显，但用户不会。

假设users_posts有以下内容：

user_id post_id
1      1
1      2
1      3
2      4    

上面的代码将回显用户一、用户二、NULL、NULL，而不是用户一、用户一、用户一、用户二。出于某种原因，它将帖子 1 与用户 1 匹配，将帖子 2 与用户 2 匹配，因为它们具有相同的 ID 号。

我做错了什么？

这是应该回声的内容：

Category One
Post One
User One
Post Two
User One
Category Two
Post Three
User One
Post Four
User Two

以下是代码回显的内容：

Category One
Post One
User One
Post Two
User Two
Category Two
Post Three
NULL
Post Four
NULL