Laravel 5.4关系

Question

I have 3 models and a pivot table:

SchoolYear - model

id

Course - model

id

schoolyear_id

course_student - pivot table

course_id

student_id

Student - model

id

Relationships are:

a SchoolYear hasMany Course

a Course belongsToMany Student trough course_student

a Student belongsToMany Course trough course_student

What is the fastest, more elegant way to find the students rolled in to a schoolyear and also to be able to sort it by Student properties?

        $year = SchoolYear::firstOrCreate(['anul'=>Carbon::now()->year]);
        $courses = $year->courses;
        $students = collect([]);
        foreach($courses as $course){
            $course_students = $course->students;
            foreach($course_students as $course_student){
                $students->push($course_student);
            }
        }
        dd($year, $students);

Answer 1

Eloquent provides a set of methods to query relationship existence. has() if there are not conditions, or whereHas() if there is a condition.

So, in your case, you want the students that have a related school year.

$year = SchoolYear::firstOrCreate(['anul'=>Carbon::now()->year]);

// assumes Student has a "courses" relationship,
// and Course has a "schoolYear" relationship
$students = Student::whereHas('courses.schoolYear', function ($query) use ($year) {
        return $query->where('anul', $year->anul);
    })
    ->get();

dd($year, $students);