Using eloquent to query multiple tables - laravel

Question

I am using Laravel 5.6. I am trying to query information from the grading_info table but I also want to return the students name and other info from the student_info table. I only want to return records in the grading_info table that are related to the currently logged in teacher. Currently its returning information for all teachers. I know I can add a where clause but I am trying to learn eloquent and was wondering if there was any way to accomplish this?
Teachers and students can have many enteries in the grading_info table and any teacher can grade any student.
I would like to return something like this
{
gradeID,
gradeDate,
gradeInfo
.....
student: {
studentName,
studentPhoneNumber,
studentEmail
......
}
}
users table (only stores teachers, not student)
id
teacher_info
teacherID (linked to id from users table)
student_info
id (auto increment. not relation to the users table)
grading_info
studentID (linked to id from student_info)
teacherID (linked to id from users)
User model
public function grades(){
return $this->hasMany(GradingInfo::class, 'studentID');
}
GradingInfo model
public function teacher(){
return $this->belongsTo(User::class, 'id', 'teacherID');
}
public function student() {
return $this->belongsTo(StudentInfo::class, 'studentID', 'id');
}
StudentInfo model
public function grades() {
return $this->hasMany(SessionInfo::class, 'studentID', 'id');
}
TeacherInfo model
// Nothing in here.
TeacherController
public function getGrades(Request $request)
{
$user = Auth::user(); // This is the teacher
$grades = $user->with('sessions.student')->orderBy('created_at', 'DESC')->get();
return response()->json(['sessions' => $sessions], 200);
}

Answer 1

You have Many to Many relationship between user(teacher) and student(student_info) tables
User Model
public function gradeStudents(){
return $this->belongsToMany(StudentInfo::class, 'grading_info', 'teacherID', 'studentID');
}
public function info(){ //get teacher info
return $this->hasOne(TeacherInfo::class, 'teacherID');
}
StudentInfo model
public function gradeTeachers(){
return $this->belongsToMany(User::class, 'grading_info', 'studentID', 'teacherID');
}
Now Fetch the data (TeacherController)
public function getGrades(Request $request)
{
$user = Auth::user(); // This is the teacher
$students = $user->gradeStudents; // it will return all graded students by logged in teacher
return response()->json(['students' => $students], 200);
}
Here grading_info is a pivot table for Many-To-Many relationship
for details check this https://laravel.com/docs/5.6/eloquent-relationships#many-to-many
Fetch Extra info from pivot table
If you want to add extra info in pivot table (grading_info) then add column (info) in this table and then need to change relationship like this
public function gradeStudents(){
return $this->belongsToMany(StudentInfo::class, 'grading_info', 'teacherID', 'studentID')
->withPivot('info')
->as('grade')
->withTimestamps();
}
Now if you fetch data
$user = Auth::user(); // This is the teacher
$students = $user->gradeStudents;
foreach($students as $student){
print_r($student);
print_r($student->grade->info);
print_r($student->grade->created_at);
}