How to paginate model using join?

I have declared this model:

PHP Code:

<?php

namespace App\Models\Blog;

use CodeIgniter\Model;

/**
 * Class PostModel.
 */
class PostModel extends Model
{
    protected $table = 'blog_posts';
    protected $primaryKey = 'id';

    protected $allowedFields = ['author_id', 'title', 'slug', 'content', 'status', 'type', 'published_date'];

    protected $useTimestamps = true;
    protected $createdField = 'created_at';
    protected $updatedField = 'updated_at';

    // trigger
    protected $beforeInsert = ['addSlug'];

    protected $validationRules = [
        'title'        => 'required|min_length[1]|max_length[60]',
        'author_id'    => 'required|integer',
        'status'       => 'required|in_list[draft,published]'
    ];

    protected $validationMessages = [];

    const ORDERABLE = [
        1 => 'title',
        2 => 'author',
        5 => 'created_at',
    ]; 


I usually apply the pagination in the following way:

PHP Code:

$post = new PostModel();
$posts = $this->post->paginate(6);
$pager = $this->post->pager; 


and then I send `$posts` and `$pager` to the view, this mechanism works just fine, but how can I paginate the post using a join?

Essentially I need to return all the blog_posts records which contains meta in the `blog_post_meta` table, this is the structure of the two tables:

blog_posts

id | title | content

blog_post_meta

id | post_id | meta_key  | meta_value

how can I use the paginate replicating this query?

PHP Code:

return $this->builder()
            ->select('blog_posts.*')
            ->join('blog_post_meta', 'blog_post_meta.post_id = blog_posts.id')
            ->where('blog_post_meta.meta_key', $key)
            ->where('blog_post_meta.meta_value', $value); 


PHP Code:

public function myPaginateMethod()
{
    $this->builder() .....
    return $this->paginate();
}
// $this->post->myPaginateMethod();

public function myMethod()
{
    $this->builder() .....
    return $this;
}
// $this->post->myMethod()->paginate(); 


PHP Code:

public function myPaginateMethod()
{
    $this->builder() .....
    return $this->paginate();
}
// $this->post->myPaginateMethod();

public function myMethod()
{
    $this->builder() .....
    return $this;
}
// $this->post->myMethod()->paginate(); 


Thanks for the answer, but I don't get it, I return this from the model:

PHP Code:

    public function getPostByMeta(string $key, string $value)
    {
        return $this->builder()
            ->select('blog_posts.*')
            ->join('blog_post_meta', 'blog_post_meta.post_id = blog_posts.id')
            ->where('blog_post_meta.meta_key', $key)
            ->where('blog_post_meta.meta_value', $value);
    } 


then in the controller:

PHP Code:

$posts = $this->post->getPostByMeta('tag', $tag->id)->paginate(10); 


I get: undefined method paginate

also, how can I access to pager?

paginate is a model method.
Therefore, your method must return an instance of the model.
You are returning a Builder instance.

See the examples I wrote more carefully.