Laravel拥有许多通过和懒惰的渴望加载

Question

I have the following models set up in Laravel 5 (everything is namespaced into App\Models, but I've removed that for readability) :

class Client extends Model {
    public function templates() { return $this->hasMany('Template'); }
    public function documents() { return $this->hasManyThrough('Template', 'Document'); }
    public function users() { return $this->hasMany('User'); }
}

class Template extends Model {
    public function client() { return $this->belongsTo('Client'); }
    public function documents() { return $this->hasMany('Document'); }
}

class Document extends Model {
    public function template() { return $this->belongsTo('Template'); }
}

In a controller, I have the current user:

$user = \Auth::user();
$client = $user->client;

I want to show a list of

• the templates for a client
• the documents for a client, separately, not grouped by template

It seems easy enough; I already have both of the relations needed. The question is, if I lazy eager load templates and documents onto $client, do I still need to eager load templates.documents (hasManyThrough) or is Laravel smart enough to realise?

$client->load( 'templates', 'documents' );
// or...
$client->load( 'templates', 'templates.documents' );
// or...
$client->load( 'templates', 'documents', 'templates.documents' );

Answer 1

I've just found that it's possible to see if a relation is loaded, so I've run artisan tinker and tested:

$c = Client::first();
array_key_exists('documents', $c->getRelations()); // false

// Loading `templates` and `documents` separately doesn't load `templates.documents`
$c = Client::first();
$c->load('templates', 'documents');
array_key_exists('documents', $c->getRelations()); // true
array_key_exists('documents', $c->templates->first()->getRelations()); // false

// Loading `documents.templates` doesn't load `documents` or `templates`
$c = Client::first();
$c->load('templates.documents');
array_key_exists('documents', $c->templates->first()->getRelations()); // true
array_key_exists('documents', $c->getRelations()); // false

So I guess the definitive answer is that if you have a hasManyThrough you must explicitly load any relation you'll access - it's not smart enough to realise that it's already loaded the relation for you.