redirect to error page in yii2 - php

Question

i'm still new in yii2.
so, make a simple project which use MVC in yii2 where the project is to output examination result.
what bugging me is, how to redirect to main page as no data found in database?
another one, i get Undefined offset: 0 which i googled say mismatch array and data not NULL.
anyhow, here are those code :
controller : StudentController.php
public function actionCall()
{
$result = $_POST['semester'];
$result_explode = explode('|', $result);
$sem = $result_explode[0];
$tahun = $result_explode[0]." ".$result_explode[1];
$send = array(
'id' => $_POST['id'],
'semester' => $sem ,
'tahun' => $tahun);
$model = new Student();
if(!$data['result']= $model->getDetails($send))
{
return $this->render('detail', $data);
}
else
{
return $this->render('detail');
}
}
public function actionSearch()
{
return $this->render('searchstudent2');
}
model : Student.php
public function getDetails($send)
{
$student = student::find()
->select('s.student_name,al.level_matric_no,al.level_semester,al.level_id,s.student_mykad, s.student_address,s.student_postcode,
s.student_state,ss.subject_code,ss.subject_name,ss.subject_credit_hour,c.course_name,st.taken_session,
g.Grade_symbol,g.Grade_value,sr.semester_gpa,sr.semester_cgpa,sr.total_point,
sr.total_credit, sr.semester_count')
->from('student AS s')
->leftJoin('a_level AS al', '`s`.`student_id` = `al`.`student_id`')
->leftJoin('subject_taken AS st', '`al`.`level_id` = `st`.`level_id`')
->leftJoin('semester_result AS sr', '`al`.`level_id` = `sr`.`level_id`')
->leftJoin('grade AS g', '`g`.`grade_id` = `st`.`grade_id`')
->leftJoin('course AS c', '`al`.`level_course_offered` = `c`.`course_id`')
->leftJoin('subject AS ss', '`ss`.`subject_id` = `st`.`subject_id`')
->where(['al.level_id'=>$send['id']])
->andWhere(['sr.semester_count'=>$send['semester']])
->andWhere(['st.taken_session'=>$send['tahun']])
->asArray()
->all();
return $student;
}
view : searchstudent2.php
<div class="container">
<div class="row">
<h2>Stylish Search Box</h2>
<div id="custom-search-input">
<?php $form = ActiveForm::begin(['action' => Url::to(['student/call']),'options' => ['method' => 'post']]) ?>
<div class="input-group col-md-12">
<select name="semester">
<option value="1|2012/2013">sem1</option>
<option value="2|2013/2014">sem2</option>
<option value="3|2014/2015">sem3</option>
<option value="4|2015/2016">sem4</option>
</select>
<br><br>
<input type="text" name="id" class="search-query form-control" placeholder="Search" />
<span class="input-group-btn">
<button class="btn btn-danger" type="submit">
<span class=" glyphicon glyphicon-search"></span>
</button>
</span>
</div>
<?php ActiveForm::end() ?>
</div>
</div>
detail.php
table 1 in detail.php
<table style="width:100%">
<tr>
<th class="tg-yw4l">Nama</th>
<th class="tg-baqh" colspan="7"><?php echo $result[0]['student_name']; ?></th>
</tr>
<tr>
<td class="tg-yw4l">Alamat</td>
<td class="tg-baqh"><?php echo $result[0]['student_address']; echo " ". $result[0]['student_postcode']; echo " ".$result[0]['student_state'];?></td>
<td class="tg-yw4l" rowspan="4"></td>
<td class="tg-yw4l">Kemasukan</td>
<td class="tg-baqh"></td>
<td class="tg-yw4l" rowspan="4"></td>
<td class="tg-yw4l" colspan="2"></td>
</tr>
<tr>
<td class="tg-yw4l">No. KP</td>
<td class="tg-baqh"><?php echo $result[0]['student_mykad']; ?></td>
<td class="tg-yw4l">Sesi</td>
<td class="tg-baqh"><?php echo $result[0]['taken_session']; ?></td>
<td class="tg-yw4l">Tahun Akademik</td>
<td class="tg-yw4l"><?php echo $result[0]['taken_session']; ?></td>
</tr>
<tr>
<td class="tg-yw4l">No. Matrik</td>
<td class="tg-baqh"><?php echo $result[0]['level_matric_no']; ?></td>
<td class="tg-yw4l">Fakulti</td>
<td class="tg-baqh"></td>
<td class="tg-yw4l" colspan="2" rowspan="2"></td>
</tr>
<tr>
<td class="tg-yw4l">Program</td>
<td class="tg-baqh"><?php echo $result[0]['course_name']; ?></td>
<td class="tg-yw4l">Semester</td>
<td class="tg-baqh"></td>
</tr>
<tr>
<td class="tg-yw4l">Pinjaman</td>
<td class="tg-baqh" colspan="7"></td>
</tr>
table 2 in detail.php
<tr>
<th class="tg-031e">BIL</th>
<th class="tg-031e">KOD</th>
<th class="tg-031e">SUBJEK</th>
<th class="tg-yw4l">KREDIT</th>
<th class="tg-yw4l">GRED</th>
<th class="tg-yw4l">MATA</th>
<!-- <th class="tg-yw4l">GPA/CGPA</th> -->
</tr>
<?php
$bil=0;
foreach ($result as $details) {
$bil++;
?>
<tr>
<td class="tg-031e"><?=$bil?></td>
<td class="tg-031e"><?php echo $details['subject_code']; ?></td>
<td class="tg-031e"><?php echo $details['subject_name']; ?></td>
<td class="tg-yw4l"><?php echo $details['subject_credit_hour']; ?></td>
<td class="tg-yw4l"><?php echo $details['Grade_symbol']; ?></td>
<td class="tg-yw4l"><?php echo $details['Grade_value']; ?></td>
</tr>
<?php } ?>
<tr>
<td class="tg-031e" colspan="2"></td>
<td class="tg-031e">TOTAL KREDIT</td>
<td class="tg-yw4l"><?php echo $details['total_point']; ?></td>
<td class="tg-yw4l">JUMLAH JAM KREDIT</td>
<td class="tg-yw4l" colspan="3"><?php echo $details['total_credit']; ?></td>
</tr>

Answer 1

Try the following steps one by one
check $_POST['semester'] and make sure it is not empty
check $model->getDetails($send) returns any result or not.
Note: find()-> ...asArray()->all() returns an empty array if no result found. so check for empty result before for render view.
if( !empty($data=$model->getDetails($send)) )
{
return $this->render('detail', ['viewData'=>$data]);
}
else
{
return $this->render('_another_view');
// or redirect to some page or do whatever
}
Note: if you send empty $data array to the view and if you use $data[0]['anything']
you will get Undefined offset: 0 error.
so if result is empty then render another view. in your case you are rendering same view 'detail' one with $data another without $data.
So there is a high chance to get Undefined offset: 0 error.
Thanks

Answer 2

If getDetails functions doesn't return data, redirect to main page:
if ( ($data = $model->getDetails($send)) != null ) {
return $this->render('detail', ['result' => $data]);
} else {
// redirect no data
return $this->redirect(['site/index']);
}