how to avoid duplicate entry in Laravel - laravel

Question

I want to give marks for each student for multiple subjects in different grades (10th,11th,12th) now i pick each student id and I can store marks for each student but i want to avoid duplicate entry for each grade and subjects. example if I give 50 marks in 10th grade for Math subject, again if i want to add marks for Math subject in 10th class, system should not accept and throw a message of duplicate entry.
NOTE: i am using Laravel 7
here it is my MarkController store method:
public function store(Request $request)
{
$this->validate($request, [
'subject_id' => 'integer',
'grade_id' => 'required',
'final_marks' => 'required',
]);
$getMarks = Mark::where('student_id',$request->student_id)->first();
if($getMarks->subject_id != $request->subject_id ){
if($getMarks->grade_id != $request->grade_id){
$marks = new Mark();
$marks->student_id = request('student_id');
$marks->subject_id = $request->subject_id;
$marks->grade_id = $request->grade_id;
$marks->final_marks = $request->final_marks;
//dd('New Marks added');
$marks->save();
}
}else{
dd('duplicate entry');
}
return back()->with('marks-created-message', 'Marks added');
}
and this is my Marks table
public function up()
{
Schema::create('marks', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('student_id');
$table->unsignedInteger('subject_id');
$table->unsignedTinyInteger('grade_id');
$table->double('final_marks',8,2);
$table->timestamps();
});
Schema::table('marks', function(Blueprint $table){
$table->foreign('student_id')->references('id')->on('students');
$table->foreign('subject_id')->references('id')->on('subjects');
$table->foreign('grade_id')->references('id')->on('grades');
});

Answer 1

From the code subject should be the only unique column because you can't assign grade without subject.
So the validation rule should look like:
$this->validate($request, [
'subject_id' => 'integer|unique:marks',
'grade_id' => 'required',
'final_marks' => 'required',
]);
Then if you need a customized message for duplicate entry then your validation should look like
$this->validate($request, [
'subject_id' => 'integer|unique:marks',
'grade_id' => 'required',
'final_marks' => 'required',
],[
'subject_id.unique' => 'Duplicate are not allowed',
]);
You can get more info: Form-request-validation

Answer 2

I solved this by adding this logic in MarkController and it worked:
public function store(Request $request)
{
$this->validate($request, [
'subject_id' => 'integer',
'grade_id' => 'required',
'final_marks' => 'required',
]);
$studentId = $request->student_id;
$subjectId= $request->subject_id;
$gradeId= $request->grade_id;
$sub = 0; // declare variable
$std =0; // declare variable
$grd =0; // declare variable
// Searching Record in DB
$marks = DB::table('marks')->where('student_id', $studentId)->where('subject_id', $subjectId)
->where('grade_id', $gradeId)->get();
//checking if record exist in DB
if($marks) {
foreach ($marks as $mark) {
$sub = $mark->subject_id; // assigning vale to variable
$std = $mark->student_id; // assigning vale to variable
$grd = $mark->grade_id; // assigning vale to variable
}
}
if ($sub == $subjectId and $std == $studentId and $grd == $gradeId){
session()->flash('marks-duplicate-message','Marks already exist.');
// return redirect()->route('marks.store',compact('std'));
return back();
}else{
$marks = Mark::create([
'student_id' => $request->student_id,
'subject_id' => $request->subject_id,
'grade_id' => $request->grade_id,
'final_marks' => $request->final_marks,
]);
session()->flash('marks-created-message','Marks added.');
return back();
}
}