Eloquent conditional where filter

Since Laravel 5.2.27, you can use conditional clauses

For example:

->when($gender, function($query) use ($gender) {
        return $query->where('gender', '=', $gender);
      })
->get();

You could use a dynamic scope

class User extends Eloquent {

    public function scopeGender($query, $gender)
    {
        if ($gender) {
           return $query->whereGender($gender);
        }
        return $query;
    }
}

Then throughout your application

...->gender($gender)->get();