Subcategories with Ajax and Codeigniter - ajax

Question

I have select box with categories and I want to display subcategories in another select box using ajax an CodeIgniter.
This is part of my view:
<script type="text/javascript">
$(document).ready(function(){
$('#tip_category').change(function(){
msg = 'category_id='+$(this).val();
$.ajax({
type : 'POST',
url : '<?php echo base_url().'admin/tips/ajax_subcategory';?>',
data : msg
});
});
});
</script>
Category:<br/>
<select name="tip_category" id="tip_category">
<?php foreach($categories as $category): ?>
<option value="<?php echo $category['id'] ?>"><?php echo $category['name'] ?>
</option>
<?php endforeach; ?>
</select><br/>
Subcategory:<br/>
<select name="tip_subcategory"
<?php if(isset($subcategories)): ?>
<?php foreach($subcategories as $subcategory): ?>
<option value="<?php echo $subcategory['id'] ?>"><?php echo $subcategory['name'] ?>
</option>
<?php endforeach; ?>
<?php endif; ?>
</select><br/>
This is part of my controller:
public function ajax_subcategory() {
$this->load->model('tips_model');
$data['subcategories'] = $this->tips_model->get_subcategories($this->input->post('category_id'));
}
My problem is that i dont know how to send data ($data['subcategories']) back to view and display subcategories. Thx for help !

Answer 1

I think you are just missing the return (in whatever format you need):
return $data;

Answer 2

You can modify your controller to:
public function ajax_subcategory() {
$this->load->model('tips_model');
$data['subcategories'] = $this->tips_model->get_subcategories($this->input->post('category_id'));
return $this->output->set_output($data);
}