数组到字符串转换在opencart中不起作用？

Actually I want to convert array data to string data for that I

amusing implode() function by comma separator but it is throwing error.

Below is my code:-

$total_data = array();

    $category_return = $this->model_catalog_category->category_name_get();
    //print_r($category_return);die;
    foreach ($category_return as $total) {
    $total_data[] = array(
            'category_id' => $total['category_id'],
            'parent_id'  => $total['category_id'],              
            'name'  => $total['name']
        );
    }
    $data = $total_data;
    //print_r($data);die;
    $fields = implode(',',$data);

    echo $fields; die;

Try this:

$total_data = array(
array(
    'category_id' => 2,
    'parent_id' => 1,
    'name' => 'First Cat'
),
array(
    'category_id' => 1,
    'parent_id' => 0,
    'name' => 'Parent Cat'
),
 array(
    'category_id' => 3,
    'parent_id' => 2,
    'name' => 'Parent Cat3'
  )
);

$output = implode(",", array_map(function($a) { return implode(",", $a); }, $total_data));
print_r($output);

Output:

2,1,First Cat,1,0,Parent Cat,3,2,Parent Cat3