Codeigniter duplicate elements from the database

Question

I've got a page that contains 4 products loaded from the database, when you scroll down you get 4 more products every time.

This products are loaded in a random way, the problem are the duplicate products.

This is the line that I used into the model:

$this->db->order_by('productID', 'RANDOM');

Without this line everything works fine. I can't use limit set to 1 because I've got:

$query = $this->db->get('product', 4, $offset);

There's a simple way to solve this problem? I've to do an array that contains all the products?

UPDATE

This is the script into the index.php

<script type="text/javascript">
$(document).ready(function(){

    var products = <?= $get_products ?>;
    var loaded_products = 0;

    $(".loadMoreProducts").click(function(){
        loaded_products += 4;

        var dati = "welcome/get_products/" + loaded_products;

        $.ajax({
          url:'welcome/get_products/' + loaded_products,
          type: 'get',
          data: dati,
          cache: false,
          success: function() {

            $.get(dati, function(data){
                $("#mainContainerProductWelcome").append(data);
            });

            if(loaded_products >= products - 4) {
                $(".loadMoreProducts").hide();
            } else {
                // load more still visible
            }
          },
          error: function() {
            // there's something wrong
          }
        });

        // show spinner on ajax request starts
        $(".loading-spinner").ajaxStart(function(){
            $(".loading-spinner").show();
            $(".text-load").hide();
        });

        // ajax request complets hide spinner
        $(".loading-spinner").ajaxStop(function(){
            $(".loading-spinner").delay(5000).hide();
            $(".text-load").show();
        });

        return false;
    });

    // submit form contact
    $(window).scroll(function() {
    if($(window).scrollTop() + $(window).height() >= $(document).height()) {
        loaded_products += 4;

        var dati = "welcome/get_products/" + loaded_products;

        $.ajax({
          url:'welcome/get_products/' + loaded_products,
          type: 'get',
          data: dati,
          cache: false,
          success: function() {

            $.get(dati, function(data){
                $("#mainContainerProductWelcome").append(data);
            });

            if(loaded_products >= products - 4) {
                $(".loadMoreProducts").hide();
            } else {
                // load more still visible
            }
          },
          error: function() {
            // there's something wrong
          }
        });

        // show spinner on ajax request starts
        $(".loading-spinner").ajaxStart(function(){
            $(".loading-spinner").show();
            $(".text-load").hide();
        });

        // ajax request complets hide spinner
        $(".loading-spinner").ajaxStop(function(){
            $(".loading-spinner").delay(5000).hide();
            $(".text-load").show();
        });
        return false;
    }
});

});
</script>

controller:

function index()
{
    $this->load->helper('url');
    $data['description'] = "Description";
    $data['keywords'] = "Keywords";
    $data['products'] = $this->abitainterni->getAllProductsLimit();
    $data['get_products'] = $this->abitainterni->get_products();
    //load view
    $this->load->view('welcome', $data);
}

function get_products($offset)
{
    $data['products'] = $this->abitainterni->getAllProductsLimit($offset);
    $this->load->view('get_products', $data);
}

model:

function getAllProductsLimit($offset=0)
{
    $sql = "SELECT * FROM product P";
    $this->db->order_by('productPosition','ASC');
    $query = $this->db->get('product', 4, $offset);
  if($query->num_rows() > 0){
    return $query->result();
  } else {
    return 0;
  }
}

function get_products()
{
    $query = $this->db->count_all_results('product');
    return $query;
}

Answer 1

Make an array of received ProducstIDs

For eg:, In the first run, you got productIDs as (1,5,8,9)

Do as follows.

$exlude_ids= 1,5,8,9;

$this->db->where_not_in('productID',$exlude_ids);

in next time, add those ids to exclude_ids and continue looping.

I've done this on one website. So if you need more help, just comment on it.

EDIT

CONTROLLER :

After fetching the first four product rows, add those product_ids into an array and pass this to model as shown below.

eg : $exlcude_ids = array(1,5,7,3);

MODEL :

function getAllProductsLimit($offset=0,$exlude_ids=array())
{
    $this->db->select(*);
    if(count($exclude_ids)>0)
    {
       $this->db->where_not_in('productID',$exlude_ids);
    }
    $this->db->order_by('productPosition','ASC');
    $query = $this->db->get('product', 4, $offset);
  if($query->num_rows() > 0)
  {
    return $query->result();
  }
  else
  {
    return 0;
  }
}