Resembling table field as some alias in Codeigniter - codeigniter

Question

In codeigniter i am creating a general function for some data insertion
for it i am keeping some norms
say i have two tables one being dt_category and the other being dt_product
here's the dt_category struture
|-------------------|---------------------|--------------------|------------------|
| category_id | category_name | category_slug | timestamp |
|-------------------|---------------------|--------------------|------------------|
and here's the dt_product structure
|-------------------|---------------------|--------------------|------------------|
| product_id | product_name | product_slug | timestamp |
|-------------------|---------------------|--------------------|------------------|
as u can see, both the tables fields just change by the field-name prefix, i mean in dt_category its category_id
and in dt_product its product_id and so on
now while calling the function to insert category data i use this method
$category_name=$this->input->post('category_name');
$insert_array=array('category_name'=>$category_name,
'timestamp'=>time());
$data['msg']=$this->erp_model->data_insert('dt_category',$insert_array);
and for product data
just this method
$product_name=$this->input->post('product_name');
$insert_array=array('product_name'=>$product_name,
'timestamp'=>time());
$data['msg']=$this->erp_model->data_insert('dt_product',$insert_array);
the function that deals with the insertion is this one
function data_insert($table,$data)
{
$this->db->insert($table,$data);
$timestamp=$data['timestamp'];
$table_nm=explode('_',$table); //spliting the table name in format dt_table_name,
$table_slug=$table_nm[1]."_"."slug";//if its dt_product table_nm[1]="product",
//if category,table_nm[1]="category"
//thus $table_slug="product_slug" or "category_slug"
$query = $this->db->select('*')
->from($table)
->where('timestamp', $timestamp)
->get();
foreach($query->result() as $r_q)
{
$id=$r_q->$table_nm[1].'_id';//i want $id value of product_id since $table_nm[1]="product"
$name=$r_q->$table_nm[1].'_name';//i want $name value of product_name since $table_nm[1]="product"
}
echo $id."-".$name;
}
in the aboce function based on the table_name
i want to fetch the value of field name
$id=$r_q->$table_nm[1].'_id'; should resemble $id=$r_q->product_id; if the table is dt_product
i know i am doing the wrong way, because ->product_id is a resultanat object while i am trying to expressing as a string,
is there a way of how i can achieve the thing,
i mean fetching the field name based on the table name;

Answer 1

Ok, i solved my problem, and here's the answer
i was trying the concatenation at the time of retrieval,
but now i did it first and then assigned the field
$tab_id=$table_nm[1].'_id';
$tab_name=$table_nm[1].'_name';
here's the resolved code
function data_insert($table,$data)
{
$this->db->insert($table,$data);
$timestamp=$data['timestamp'];
$table_nm=explode('_',$table);
$table_slug=$table_nm[1]."_"."slug";
echo $table_slug;
$query = $this->db->select('*')
->from($table)
->where('timestamp', $timestamp)
->get();
$tab_id=$table_nm[1].'_id';
$tab_name=$table_nm[1].'_name';
foreach($query->result() as $r_q)
{
$id=$r_q->$tab_id;
$name=$r_q->$tab_name;
}
echo $id."-".$name;
}