Laravel 5.3 eloquent 3 table join using models - laravel

Question

I read this post which helped, but need more guidance please.
I need a set of Results for a particular $batteryid (on Result) and a particular $age (on Test model) and a particular $gender (from Athlete). Each Test belongs to one athlete. Each test has many results.
Model Battery:
class Battery extends Model{
public function results(){
return $this->hasMany('App\Result');
}
}
Model Result:
class Result extends Model{
public function test(){
return $this->belongsTo('App\Test', 'test_id');
}
public function battery(){
return $this->belongsTo('App\Battery', 'battery_id');
}
}
Model Test:
class Test extends Model{
public function athlete(){
return $this->belongsTo('App\Athlete', 'athlete_id');
}
public function results(){
return $this->hasMany('App\Result');
}
}
I get the correct results with the following, but it's two queries:
$tests = Test::whereHas('Athlete', function($query) use($gender){
$query->wheregender($gender);
})->where('age', $age)->get();
$test_ids = $tests->pluck('id');
$results = Result::where('battery_id', '=', $battery)
->whereIn('test_id', $test_ids)
->get();
I'd like to use model approach, but am completely stuck. test.age not recognised and not sure how to get the age from athlete model. My attempt:
$results = Result::with('test')
->where('test.age', '=', $age)
->join('batteries', 'batteries.id', '=', 'test.battery_id')
//->where('test->athlete().gender', '=' $gender)
->where('battery_id', '=', $battery)
->get();

Answer 1

You can use whereHas for the condition and with method for eager loading it.
$results = Result::whereHas('test', function($q) use ($age) {
$q->where('age', '=', $age);
$q->whereHas('athlete', function ($q) {
$q->where('gender', 'male');
});
})
->with('test')
->whereHas('battery', function($q) use($battery) {
$q->where('battery_id', '=', $battery);
})
->with('battery')
->get();