Issue adding days in a for loop

you have $sesssiondate = $coursedate inside your for loop so it keeps getting reset

Hey, I took a look at your code and I noticed that you're incrementing a $no_courses variable after every parent for loop. I think that is redundant, since it will always equal $validated['no_classes], right?

To address your problem, in your inner for loop you first set $sessionDate = $courseDate, and at the end you increase the days on this date. Then, in your next loop, you'll reset the updated $sessionDate back to $courseDate.

    for ($a = 0; $a < $validated['attendance_sessions']; $a++) {
        $sesssionDate = $courseDate;
    // here we've reset the updated $sessionDate back to $courseDate.
        
        Attendancesession::create([
            'attendances_id'    => $attendance->id,
            'session_starttime' => $validated['start_time'],
            'session_endtime'   => $validated['end_time'],
            'session_date'      => $sesssionDate,
        ]);
        
        $sesssionDate = $sesssionDate->addDays($validated['session_interval']); 
    // here we've updated $sessionDate
    }

also, this;

$sesssionDate = $sesssionDate->addDays($validated['session_interval']);

Carbon modifies itself when you do things like adding days. So this will behave the same

$sesssionDate->addDays($validated['session_interval']);

hey @johnbraun , snap!

@SNAPEY - You'd beat me to it! :-D

How about mutable Carbon object? $courseDate is a mutable Carbon object and $sesssionDate is actually modifying $courseDate. I think he should use a new CarbonImmutable object inside the second loop for $sesssionDate so it can generate correct days from the result of $courseDate->add($validated['interval'], 'day');

@mgsmus its something to consider but does not fix the problem

@SNAPEY - @snapey - I did not perceive that. Thank you, that helps.

So....I made some changes and the initial changes seem to indicate it is working

$courseDate = new Carbon($validated['start_date']);
for($i = 0; $i < $validated['no_classes'];$i++) {
                $course = Course::create([
                    'course_cat_id' => $coursecat->id,
                    'name' => $coursecat->name . ' : ' . $courseDate->format('Y-m-d'),
                    'start_date' => $courseDate->format('Y-m-d'),
                    'start_time' => $validated['start_time'],
                    'end_time' => $validated['end_time'],
                    'summary' => $validated['description'],
                ]);
                $sessionDate = new Carbon($courseDate); // Make a new carbon object and copy it into session date before adding days. This is then used in second iteration. and can be modified independantly of $courseDate
                $courseDate->add($validated['interval'], 'day');
                $no_courses++;
                $attendance = Attendance::create([
                    'course_id' => $course->id,
                ]);
                for($a = 0; $a < $validated['attendance_sessions'];$a++) {
                    Attendancesession::create([
                        'attendances_id'    => $attendance->id,
                        'session_starttime' => $validated['start_time'],
                        'session_endtime' => $validated['end_time'],
                        'session_date' => $sessionDate,
                    ]);
                    $sessionDate->add($validated['session_interval'], 'day');
                }

Thanks everyone for your help. @snapey @johnbraun @mgsmus

@CTYLER - Great! you're welcome

@snapey @johnbraun @mgsmus I have a question concerning this code. So, this is all happening inside the controller. Should i break this up into methods. So for instance, make the outer and inner for loops their own methods. And if so, would they go into their respective models or would it be better someplace else. I appreciate your thoughts on it.

To make the code more readable, you could try to refactor from the inside-out thus first creating a separate method for the inner for() loop:

for($a = 0; $a < $validated['attendance_sessions'];$a++) {

    Attendancesession::create([
        'attendances_id'    => $attendance->id,
        'session_starttime' => $validated['start_time'],
        'session_endtime' => $validated['end_time'],
        'session_date' => $sessionDate,
    ]);

    $sessionDate->add($validated['session_interval'], 'day');

}

// first refactor step:

public function createAttendanceSession($validated, $attendance, $sessionDate)
{
    for ($a = 0; $a < $validated['attendance_sessions']; $a++) {
        Attendancesession::create([
            'attendances_id'    => $attendance->id,
            'session_starttime' => $validated['start_time'],
            'session_endtime' => $validated['end_time'],
            'session_date' => $sessionDate,
        ]);

        $sessionDate->add($validated['session_interval'], 'day');
    }

    return true;
}

$courseDate = new Carbon($validated['start_date']);
for($i = 0; $i < $validated['no_classes'];$i++) {
                $course = Course::create([
                    'course_cat_id' => $coursecat->id,
                    'name' => $coursecat->name . ' : ' . $courseDate->format('Y-m-d'),
                    'start_date' => $courseDate->format('Y-m-d'),
                    'start_time' => $validated['start_time'],
                    'end_time' => $validated['end_time'],
                    'summary' => $validated['description'],
                ]);
                $sessionDate = new Carbon($courseDate); // Make a new carbon object and copy it into session date before adding days. This is then used in second iteration. and can be modified independantly of $courseDate
                $courseDate->add($validated['interval'], 'day');
                $no_courses++;
                $attendance = Attendance::create([
                    'course_id' => $course->id,
                ]);

// after initial for loop

$this->createAttendanceSessions($validated, $attendance, $sessionDate);

Just to be clear: the refactoring step doesn't stop here, I only show the first step you could take.

Now, after the first refactor step, a lot of things could be cleaned up: doubly used variables, lower the amount of variables we have to pass to the function(s), unclear variable names ($a), what should we return from the function (true, or a collection of created attendance sessions?), maybe we could use a collection instead of a for loop, maybe the whole API should be reworked. These are decisions you'd need to overthink.

Have you checked out Jeffrey's course on refactoring yet? https://laracasts.com/series/whip-monstrous-code-into-shape

@johnbraun - Thanks, your the best. Heading over there now!

be sure to mark it complete. Pick John as he has been most helpful.

@SNAPEY - Thanks ;-)

@JOHNBRAUN - No problem! I appreciate the time and effort!