Laravel 4 and Eloquent: retrieving all records and all related records

Question

I have two classes: Artist and Instrument. Each Artist can play one or more Instruments. And each Instrument can be assigned to one or more Artists. So, I've set up the following Classes:

Artist.php

public function instruments() {
    return $this->belongsToMany('App\Models\Instrument');
}

Instrument.php

public function artists() {
    return $this->belongsToMany('\App\Models\Artist');
}

Then I have three database tables:

artists: id, firstname, lastname, (timestamps)
instruments: id, name
artist_instrument: id, artist_id, instrument_id

I'm able to successfully retrieve a one artist and their associated instruments like so:

ArtistController.php

$artist = Artist::find($artist_id);
$instruments = $artist->instruments()->get();
return \View::make('artists')->with('artists', $artists)->with('instruments', $instruments);

I have 3 questions:

1. In my view, I can output the $artist like:

   {{ $artist->firstname }}
   

   and I can iterate through $instruments like:

   @foreach ($instruments as $instrument)
       <h2>{{ $instrument->name }}</h2>
   @endforeach
   

   but is it possible to iterate over $artist (I know there's only one — see #2) and for each $artist iterate over their $instruments?

2. In my controller, how would I get all artists and for each of those their associated instruments with the end goal of iterating through them in my view as described in #1.

3. Is it possible to only retrieve specific columns in the above example of ArtistController.php? I've tried this:

   $artist = Artist::where('id', $artist_id)->get('firstname');
   $instruments = $artist->instruments()->get();
   return \View::make('artists')->with('artists', $artists)->with('instruments', $instruments);
   

   but I get an error saying Collection::instruments() is undefined.

I'm assuming there's something not right in my model relationships. I've also tried defining my relationship in Artist.php with a hasMany (I think it makes more sense to say "Each Artist hasMany Instruments", but that gives me an error because it's expecting a table named artists_instruments and it's also trying to retrieve columns that wouldn't exists in that table (like name).

Answer 1

Your model relationships are fine.

Controller:

$artists = Artist::with('instruments')->get();

return \View::make('artists')->withArtists($artists);

View:

@foreach ($artists as $artist)

    <h1>{{ $artist->firstname }}</h1>

    @foreach ($artist->instruments as $instrument)

        <h2>{{ $instrument->name }}</h2>

    @endforeach

@endforeach