PHP：在codeigniter中没有更新组合框值

I have table view of some product which get data from database, there are two option edit and delete when I click on edit it shows particular data.
There is 2 categories inside combo box say Pizza and Sandwich.

By default Pizza is selected, and the value in database is also Pizza only now the problem begins, when I select sandwich instead of pizza the value in database is not getting updated.

I have used codeigniter framework for this project, so I want solution in same framework.
I have searched in google and many other way but hard luck, not getting proper solution what I want.

Any help would be appreciated. Thank in advance.

code: Controller

function products_edit($product_id)
{
$this->load->library('form_validation');
$this->load->helper('form');  
$this->load->helper('html');    
$this->load->model('products_model');
$data=$this->products_model->general();
$product = $this->products_model->get_product($product_id);
$category['categories']=$this->products_model->get_category();
$this->data1['title'] = 'Edit Product';

//validate form input
$this->form_validation->set_rules('name', 'Product name', 'required|xss_clean');
$this->form_validation->set_rules('description', 'Description', 'required|xss_clean');
$this->form_validation->set_rules('price', 'Price', 'required|xss_clean');
$this->form_validation->set_rules('is_featured', 'Is Featured', 'required|xss_clean');
$this->form_validation->set_rules('prorder', 'Order', 'required|xss_clean');

if (isset($_POST) && !empty($_POST))
{       
    $data1 = array(
        'product_name'=> $this->input->post('name'),
        'product_desc'=> $this->input->post('description'),
        'product_category'=> $this->input->post('category'),
        'extras'=> $this->input->post('extras'),
        'price'=> $this->input->post('price'),
        'is_featured'=> $this->input->post('is_featured'),
        'prorder' => $this->input->post('order'),
    );

    if ($this->form_validation->run() === true)
    {
        $this->products_model->updateproducts($product_id, $data1);

        $this->session->set_flashdata('message', "<p>Product updated successfully.</p>");

        redirect('products_controller/products_edit/'.$product_id);
    }           
}

$this->data1['message'] = (validation_errors() ? validation_errors() : $this->session->flashdata('message'));

$this->data1['product'] = $product;
//$this->data1['category']=$category;

//display the edit product form     
$this->data1['name'] = array(
    'name'      => 'name',
    'id'        => 'name',
    'type'      => 'text',
    'style'     => 'width:300px;',
    'value'     => $this->form_validation->set_value('name', $product['product_name']),
);

$this->data1['description'] = array(
    'name'      => 'description',
    'id'        => 'description',
    'type'      => 'text',
    'cols'      =>  40,
    'rows'      =>  5,
    'value'     => $this->form_validation->set_value('description', $product['product_desc']),
);

    $category1=$this->products_model->get_category();
    $category1['value']=set_value('category',$product['product_category']);
    $temp=array(
    '1'=>$category1['value'],
    );
    $category1=array_diff($category1,$temp);
    $category1['value']=set_value('category',$product['product_category']);

    $this->data1['category']=$category1;

$this->data1['extras'] = array(
    'value'     => $this->form_validation->set_value('extras', $product['extras']),
);

$this->data1['price'] = array(
    'name'      => 'price',
    'id'        => 'price',
    'type'      => 'text',
    'style'     => 'width:40px;text-align: right',
    'value'     => $this->form_validation->set_value('price', $product['price']),
);

$this->data1['is_featured'] = array(
    'name'      => 'is_featured',
    'id'        => 'is_featured',
    'type'      => 'text',
    'style'     => 'width:40px;text-align: right',
    'value'     => $this->form_validation->set_value('isfeatured', $product['is_featured']),
);

$this->data1['prorder'] = array(
    'name'  => 'prorder',
    'id'    => 'prorder',
    'type'  => 'text',
    'style' => 'width:40px;',
    'value' => $this->form_validation->set_value('prorder', $product['prorder']),
);
$this->load->view('products_edit', $this->data1);
} 

Model:

function get_product($product_id) {
$this->db->select('product_id,product_name,product_desc,product_category,extras,price,is_featured,prorder');
$this->db->where('product_id', $product_id);
$this->db->distinct('product_category');
$query = $this->db->get('product');
return $query->row_array();
}

function updateproducts($product_id, $data)
{
    $this->db->where('product_id', $product_id);
    $this->db->update('product', $data);
}

View :

<?php $product_id = $product['product_id']; ?>
<?php echo form_open("products_controller/products_edit/$product_id");?>
<table width="500" border="1" cellpadding="0" cellspacing="2" align="center">
<tr>
<td width="130" align="right"> Product Name: </td>
<td><?php echo form_input($name); ?></td>
</tr>
<tr>
<td width="130" align="right"> Product Description: </td>
<td><?php echo form_textarea($description); ?></td>
</tr>
<tr>
<td align="right">Product Category:</td>
<td>
<?php echo form_dropdown("product_id",$category,'value')?>      
</td>
</tr>
<tr>
<td align="right">Extras:</td>
<td><?php echo  form_dropdown("product_id",$extras,"#","id='product_id'");?></td>
</tr>
<tr>
<td align="right">Price:</td>
<td><?php echo form_input($price); ?></td>
</tr>
<tr>
<td align="right">Is Featured:</td>
<td><?php echo form_input($is_featured); ?></td>
</tr>
<tr>
<td align="right">Order:</td>
<td><?php echo form_input($prorder); ?></td>
</tr>
<tr>
<td>&nbsp;</td>
<td><?php echo form_submit('submit', 'Submit');?>
</td>
</tr>
</table>
<table align="center">
<tr>
<td>
<?php echo form_close(); ?>
<?php echo form_open("products_controller/products_search");?>
<?php echo form_submit('submit', 'Back');?>
<?php echo form_close(); ?>