saveall on habtm creates duplicate new rows - php

Question

I have a simple HABTM with a lessons/Students table. i simply create a new lesson with an existing student via a while loop , so I should get 2 new rows. I am testing this function. What I get is 4 new rows in the lesson table instead of 2. I have no idea why the extra 2 rows are created as they are a duplicates of the 2 new rows which are outputted in debug. Everything is correctly saved like the entries in join lesson/student table and all the FK exist.
Just to add confusion, sometimes the same code produces the desired 2 rows . This is unstable so I am doing something wrong. I followed the array setup for habtm as in the manual for saves.
http://book.cakephp.org/2.0/en/models/saving-your-data.html
private function book_lessons($lesson=null) {
// debug( $lesson);
$i=0;
while ($i<2)
{
$date=date('Y-m-d');
$data[$i]=array();
$this->Lesson->create();
$data[$i]['Lesson']['lesson_date']= $date;
$data[$i]['Lesson']['start_time']= $lesson['Lesson']['start_time'];
$data[$i]['Lesson']['end_time']=$lesson['Lesson']['end_time'];
$data[$i]['Lesson']['schedule_rec']= 1;
$data[$i]['Lesson']['subject_id']= $lesson['Lesson']['subject_id'];
$data[$i]['Lesson']['tutoring_type_id']= 1;
$data[$i]['Lesson']['tutor_id']= $lesson['Lesson']['tutor_id'];
$data[$i]['Lesson']['subject_id']= $lesson['Lesson']['subject_id'];
$data[$i]['Lesson']['term_id']= $lesson['Lesson']['term_id'];
$data[$i]['Student']['id']=$lesson['Student']['id'];
$i=$i+1;
}
$this->Lesson->saveAll($data);
public $hasAndBelongsToMany = array(
'Student' => array(
'className' => 'Student',
'joinTable' => 'lessons_students',
'foreignKey' => 'lesson_id',
'associationForeignKey' => 'student_id',
'unique' => 'keepExisting',
)
);
array(
(int) 0 => array(
'Lesson' => array(
'lesson_date' => '2015-06-11',
'start_time' => '16:00:00',
'end_time' => '17:00:00',
'schedule_rec' => (int) 1,
'subject_id' => '16',
'tutoring_type_id' => (int) 1,
'tutor_id' => '12',
'term_id' => '10'
),
'Student' => array(
'id' => '206'
)
),
(int) 1 => array(
'Lesson' => array(
'lesson_date' => '2015-06-11',
'start_time' => '16:00:00',
'end_time' => '17:00:00',
'schedule_rec' => (int) 1,
'subject_id' => '16',
'tutoring_type_id' => (int) 1,
'tutor_id' => '12',
'term_id' => '10'
),
'Student' => array(
'id' => '206'
)
)
)

Answer 1

Move the $this->Lesson->create(); out of the loop. Cake will still save multiple records when you have only in create() method.