message: undefined variable in view - codeigniter

Question

I am trying to get the data in my view in codeigniter but it gives me a Message: Undefined variable: topics_array
here is my model :
public function studentTopics($courseId, $periodId)
{
$this->dbi->select('topicitem.TopicItemID, topicItem.Content');
$this->dbi->from('topicitem, topics, periods');
$this->dbi->where('topics.PeriodItemID', $periodId)
->where('topics.TopicItemID = topicitem.TopicItemID')
->where('topics.PeriodItemID = periods.PeriodItemID')
->where('periods.CourseID', $courseId);
$res = $this->dbi->result_array();
return $res;
}
here is my controller
public function student_topic($courseId, $periodId)
{
$this->load->library('table');
$this->load->model('Student_model');
$data['topics_array'] = $this->Student_model->studentTopics($courseId, $periodId);
$this->load->view('Student/StudentView', $data);
}
and my view
<?php
$courseID = $this->uri->segment(4);
$periodID = 1;
foreach ($topics_array as $key =>$value) {
echo "<tr>
<td>".$value['Content']. "</td>
</tr>"; }?>

Answer 1

You seem to be missing a get().
$res = $this->dbi->get()->result_array();
return $res;

Answer 2

Hope this will help you :
change this line of code : $res = $this->dbi->result_array();
$this->dbi->select('topicitem.TopicItemID, topicItem.Content');
$this->dbi->from('topicitem, topics, periods');
$this->dbi->where('topics.PeriodItemID', $periodId)
->where('topics.TopicItemID = topicitem.TopicItemID')
->where('topics.PeriodItemID = periods.PeriodItemID')
->where('periods.CourseID', $courseId);
$query = $this->dbi->get(); // missing this line of code
$res = $query->result_array();
for more : https://www.codeigniter.com/user_guide/database/query_builder.html#looking-for-specific-data