Condition for related table ORM Kohana - php

Question

For example I have 3 tables:
songs(id, song_name)
song_category(id, song_id, category_id)
categories(id, name)
I want to get songs which have categories with id higher than 5. I want to do it using ORM, not with simple SQL query. Is it possible to do it with one query like this:
$songs = ORM::factory("songs")->where("category.id > 5")

Answer 1

No, you cannot do this with a single Kohana ORM call.
The best way I have found to do it is something like this, which makes a modification to the SQL query that the ORM will generate:
// Get the basic "song" model
$songs = ORM::factory("songs");
// Get the information about how it is connected to
// the "category" model using the `through` model
$song_relations = $results->has_many();
$category_relation = $song_relations['categories'];
$through = $category_relation['through'];
// Join on `through` model's target foreign key (far_key) and `target` model's primary key
$join_col1 = $through.'.'.$category_relation['foreign_key'];
$join_col2 = $songs->object_name().'.'.$songs->primary_key();
$songs->join($through)->on($join_col1, '=', $join_col2);
// Now, filter on the
$songs->where($through.'.'.$category_relation['far_key'], '>', 5);
$arr = $results->find_all()->as_array();
You could save some code by hardcoding the values in the join method call, but this way leverages the ORM relation definitions that you already have.
This assumes that your Song model has the following code in it:
protected $_has_many = [
'categories' => [
'model' => 'category',
'through' => 'song_category',
'foreign_key' => 'song_id',
'far_key' => 'category_id',
]
];