Generate PHPExcel Laravel Excel with many to many relations - php

Question

I am working on an exam/quiz app and it creates tests/quizzes for users and now I must create a set of spreadsheets that contain data such as the present students in a given exam, grades charts and so on.
Bu so far all I managed to create is a sheet with ALL the users using `->fromModel' but if I use any relation and or constrain I get an empty sheet.
I have this models:
<?php
namespace EMMA5;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\DB;
class Exam extends Model
{
//
protected $dates = ['created_at', 'updated_at', 'applicated_at'];
protected $fillable = [
'applicated_at',
'duration',
'board_id',
'passing_grade',
'annotation'
];
public function board()
{
return $this->belongsTo('EMMA5\Board');
}
public function users()
{
return $this->belongsToMany('EMMA5\User')->withPivot('active', 'started_at', 'ended_at', 'seat', 'location_id');
}
...
User model (abbreviated)
class User extends Authenticatable
{
...
//Relations
public function answers()
{
return $this->hasMany(Answer::class);
}
public function exams()
{
return $this->belongsToMany('EMMA5\Exam')->withPivot('active', 'started_at', 'ended_at', 'location_id');
}
...
And I am trying to create a sheet with the users for a given exam:
(This is from my ExamController.php)
/**
* Returns a spreadsheet with only the students that were present
*
* #return PHPOffice
*/
public function gradesSpreadshet(Exam $exam)
{
$grade = new Grade;
$gradedStudents = $grade->allStudents($exam)->toArray();
//dd(\EMMA5\Exam::find(195)->with('users')->get());
//dd($exam->answers->answer);
$data = $exam->users;
return Excel::create("FinalGrades", function ($excel) use($data) {
//Create sheet to be able to return something to keep on testing
//Another sheet
$excel->sheet('Primera hoja', function ($sheet) use($data) {
$sheet->fromArray($data);
});
})->export('xlsx');
}
And I get an empty sheet.
I already tried with ->fromArray() and ->fromModel() .
Will appreciate any input.

Answer 1

Some time passed and nobody answered but I found a solution.
I do not know if it will be helpful for someone else.
The way I got the results couldn't be read by Excel Laravel. So I created a helper function with a callback.
public static function collectionToArray(Array $collect = null)
{
return array_map(function ($array) use($collect)
{
foreach ($array as $key => $value) {
$resultArray[$key] = $value;
}
return $resultArray;
}, $collect);
}
This returns a simplified version of the Collection that can be easily read by Excel Laravel.