Codeigniter using different function's where clause - php

Question

I have a Postgres database with a table for orders and a table order_contents, which includes all items of the order, and the order_id. I'm trying to make a view with order history.
In my model I have two functions, one to retrieve orders, and another to retrieve all the contents of an order, like so:
function retrieve_orders($userID){
$query = $this->db->get('orders');
$this->db->where('user_id', $userID);
return $query->result_array();
}
function get_order_contents($orderID){
$query = $this->db->get('order_contents');
$this->db->where('order_id', $orderID);
return $query->result_array();
}
So in my controller I call retrieve_orders() and pass the resulting array to the view. In the view, I want to create an HTML table for each order with all it's contents. So I iterate through each order and call get_order_contents in the loop.
Everything should work, however what happens is this error shows up in the source:
Error Number: ERROR: column "user_id" does not exist
LINE 3: WHERE "user_id" = '3'
^SELECT *
FROM "order_contents"
WHERE "user_id" = '3'
As you can see, for some reason, when I call get_order_contents() in the view, it uses the where clause I specified for the retrieve_orders() function.
What I have done so far is try to manually stop caching, but to no avail. Any help here is appreciated.

Answer 1

In each function, try to put where() before get().
When you try to get() order_contents it will use where clause from previous where().
Common practice is, use get() at the last call of $this->db after other calls such as where(), etc. See the Active Record documentation in codeigniter.

Answer 2

Chain your db functions like this
return $this->db->where('user_id', $userID)
->get('orders')
->result_array();

Answer 3

why not use $this->db->get_where()