Laravel 5.7 query with 3 tables

I'm pretty new to Laravel and i got stuck with building a more complex query:

I've 3 tables with their models:

Codes:

• id
• description

• factor

  public function purposes() {
      return $this->hasMany('App\Purpose', 'code_purposes', 'code_id', 'purpose_id'); 
  //I could be wrong here
  }
  
  

Purpose:

• id
• name
• description

Code_purposes:

• code_id

• purpose_id

    public function codes() {
      $this->belongsToMany('App\Code'); //I could be wrong here
  }
  
  public function purposes() {
      $this->belongsToMany('App\Purpose'); //I could be wrong here
  }
  
  

What I want is to fetch all the codes with the condition where the purposes name = 'some_name'

I thought this would be easy with the relationships, but I can't figure it out.

So how do I do this in Laravel?

via Chebli Mohamed