dependent dropdown when edit in yii - drop-down-menu

Question

Problem in dependent dropdowns when editing in my yii application.
While editing, the drop downs are not automatically selected.
In my view,
array('class' => 'CButtonColumn',
'header' => 'Manage',
'template' => '{update} {view} {delete}',
'htmlOptions' => array('width' => '20%'),
'buttons' => array(
'update' => array(
'label' => '',
'imageUrl' => '',
'options' => array('class' => 'glyphicon glyphicon-pencil'),
),
'view' => array(
'label' => '',
'imageUrl' => '',
'options' => array('class' => 'glyphicon glyphicon-eye-open'),
),
'delete' => array(
'label' => '',
'imageUrl' => '',
'options' => array('class' => 'glyphicon glyphicon-remove'),
),
),
),

Answer 1

<div class="form-group">
<label for="reg_input" class="req">Course</label>
<?php
$course = CHtml::listData(Course::model()->findAll(), 'courseid', 'course_name');
echo CHtml::activeDropDownList($model, 'courseid', $course, array(
'empty' => 'Select Course', 'class' => "form-control",
'ajax' => array(
'type' => 'POST',
'url' => CController::createUrl('Assignment/Fetchbatch'),
'update' => '#' . CHtml::activeId($model, 'batchid'))));
?>
<?php echo $form->error($model, 'courseid', array('class' => 'school_val_error')); ?>
</div>
<div class="form-group">
<label for="reg_input" class="req">Batch</label>
<?php
$batch = CHtml::listData(Batch::model()->findAll(), 'batchid', 'batch_name');
echo $form->dropDownList($model, 'batchid', $batch, array('prompt' => 'Select Batch',
'class' => "form-control",
'ajax' => array(
'type' => 'POST',
'url' => CController::createUrl('Assignment/Fetchsubject'),
'update' => '#' . CHtml::activeId($model, 'subjectid'))));
echo $form->error($model, 'batchid', array('class' => 'school_val_error'));
?>
</div>
Second dropdown get the data, to change of first dropdown. At this condition the dropdown will not be selected automatically. Because when editing, that value is not there. So I fixed this problem, my code is above this.