Sails.js associations

I am beginning with sails.js and I am completely lost with my sql queries.

I have the following tables :

genres
+-----------+--------------+------+-----+
| Field     | Type         | Null | Key |
+-----------+--------------+------+-----+
| id        | int(6)       | NO   | PRI | 
| name      | varchar(100) | NO   |     | 
| slug      | varchar(255) | NO   |     |
| type      | varchar(32)  | NO   |     | 
| parent_id | int(11)      | YES  | MUL | 
+-----------+--------------+------+-----+
genres_radios
+----------+--------+------+-----+
| Field    | Type   | Null | Key |
+----------+--------+------+-----+
| genre_id | int(6) | NO   | MUL |
| radio_id | int(6) | NO   | MUL |
+----------+--------+------+-----+
radios
+-----------+--------------+------+-----+
| Field     | Type         | Null | Key |
+-----------+--------------+------+-----+
| id        | int(5)       | NO   | PRI | 
| name      | varchar(100) | NO   |     | 
| slug      | varchar(100) | NO   |     |
| url       | varchar(100) | NO   |     | 
+-----------+--------------+------+-----+

I want to retrieve the radios and their associated genres. I managed to do it using the Model.query("Select * FROM ...") but I'd like to do it using the populate method. I had a look at the docs, but I am a bit confused with the "via", "through", ...