The built in CodeIgniter paging library is fairly simple to use by itself.. however, where its functionality ends is at the point that most developers will want to customize, which is really as it should be. However, some beginning CodeIgniterers (eh?) or PHPers may find this drop-off point a little disconcerting, and may want something a little more simple. This tutorial will aim to take care of them.

Basically, my method involves passing the necessary data to a paging function within the controller. If you are using multiple controllers, I would suggest either extending the paging library, or creating another class and loading it.. but again, the idea is to keep it really simple - so you’ll have to work that out on your own.

Here’s the paging function:

Your controller:

function _paging($limit=10,$total_rows, $page,$uri_segment=3)
{
     $this->load->library('pagination');
     $config['uri_segment'] =$uri_segment;
     $config['base_url'] = site_url('/yourcontrollername/'.$page.'/');
     $config['total_rows'] = $total_rows;
     $config['per_page'] = $limit;
     $config['num_links'] = 10;

     $config['full_tag_open'] = '
';
     $config['full_tag_close'] = '



';

     $config['first_link'] = '«';
     $config['last_link'] = '»';
     $config['next_link'] = '»';
     $config['prev_link'] = '«';

     $this->pagination->initialize($config);

     return $this->pagination->create_links();
}

Ok, that probably doesn’t make a lot of sense.. there’s some stuff missing, and we’ll go over that here.

First, this function is a helper, and gets called by another function within the controller… basically, any other function which needs paging applied. So, lets say for example that we want to load a list of fruits in inventory at your local organic market (because organic rocks!)

So, we’re going to have a function which gets the fruits from the database, and begins like this:

function get_fruits()
{
     if($this->uri->segment(3) == '') $offset = 0;
     else $offset = $this->uri->segment(3);
}

Wait a minute…. what kind of beginning is that? Well, the first thing we want to do, is figure out what page we’re on. Since CodeIgniter’s paging class appends the page number onto the end of the URI, we check to see if it has a value.. if not, we assign the offset to 0, otherwise, we set it equal to that value (so on page 2, the offset would be 1). This isn’t the TRUE offset, in the sense that we don’t want to search our database from record one. Later on, we’ll multiply the page number by the limit (the number of records we are returning on each page, to get the true offset). So, the offset is in essence the page number - 1. If our limit is 20 for example, then when we do the math, page 2 will start at record 20. Page 3 will start at record 40 (2*20) and so on.

function get_fruits()
{
     if($this->uri->segment(3) == '') $offset = 0;
     else $offset = $this->uri->segment(3);
     $limit = 20;
     $offset*=  $limit;
}

Here, we have set the total number of rows returned on the page for this function, and determined the starting point for the database by multiplying our page number ($offset) by it.

An important thing to keep in mind. The offset doesn’t have to be at segment 3. It is always the last segment. You can either hard code where that is in your page, or you can figure it out dynamically - but that’s beyond the scope of this tutorial. Why would it NOT be 3? Say for example you offered a drop-down where the user could select WHICH type of fruit to view, such as citrus. You’d need to maintain that choice as you went through the paging, so it would probably be easiest to add it in as a segment. At which point, the offset would be at uri->segment(4).

Let’s return to the function:

function get_fruits()
{
     if($this->uri->segment(3) == '') $offset = 0;
     else $offset = $this->uri->segment(3);
     $limit = 20;
     $offset*=  $limit;

     $this->load->model('model_fruits');
     $results = $this->model_fruits->get_fruits($limit $offset);
}

The next two lines are where you’d load your database functions (the model, which should be in the model folder), and then call the function get_fruits(), passing in the $offset you determined in the first 3 lines.
In the case of the example of loading just ‘citrus’, you could also pass that uri->segment to the get_fruits function, and go from there.

At this point, we’re going to flip over to models/model_fruits.php to look at how we’re going to get the data out of the database. Please refer to the CodeIgniter user guide for information on how a model should be setup.

Your model:

function get_fruits($limit,$offset)
{
     $this->db->limit($limit,$offset);
     $query = $this->db->get('fruits');
     if($query->num_rows() > 0)
     {
           $results['results'] = $query->result(); 

           $this->db->select('COUNT(*) as $totalRows');
           $query = $this->db->get('fruits');
           $row = $query->row();
           $results['totalRows'] = $row->totalRows;    

           return $results;
     }
     else return FALSE;

}

Yes, that’s a bit longer section of code. If you aren’t familiar with CodeIgniter’s active record class, here’s the lowdown on what the above means.

1. First, we set the database limit and offset as passed from our controller. This will handle the records that are returned for the page.
2. Next, we set our actual query to a variable ($query makes sense). CodeIgniter’s query object is returned into this variable, and at that point we can retrieve the data from it.
3. We then use the built-in num_rows() function to make sure we got some data back. If we didn’t, none of this other stuff really matters.
4. Assuming we got data, we start an array named ‘$results’ and insert a key into it, again called ‘results’, to store the actual database data returned by our query.
5. At this point, we need to get the total number of rows, so our _paging function knows how many page links to create. We don’t want to use the $query->num_rows() to set it, because it is already being limited to the value passed by the controller. Instead, we do another database call to get the COUNT(*), which quickly returns the number of rows in a table that match the query. You COULD select a column and run the query without a limit, and then use $query->num_rows, but its very inefficient for the database, and is poor practice. You also must be aware to give the COUNT(*) a different name, because you can’t tell CodeIgniter to return $row->COUNT(*)… it will think you’re trying to run a function!
6. We run the query again, set a variable to only the first row of our dataset (since only one row is returned) and then set another key in the $results array to the totalRows data we just retrieved. At that point, we send the data and the total rows back to the controller. If by any chance our query had returned no records, we send back a ‘false’ signal so the controller knows what happened.

So now we’re back at our controller. We’ve gotten our data from the database in the model, and are ready to go to work with it. The controller’s get_fruits() function now looks like this:

function get_fruits()
{
     if($this->uri->segment(3) == '') $offset = 0;
     else $offset = $this->uri->segment(3);
     $limit = 20;
     $offset*=  $limit;

     $this->load->model('model_fruits');
     $results = $this->model_fruits->get_fruits($limit $offset);

     if($results!=false)
     {
         $results['paging'] = $this->_paging($limit,$results['totalRows'], 'get_fruits',3);
     }

     $this->load->view('list_fruits',$results);
}

So, we make sure that our model didn’t tell the controller that there was no data (because there’s no point doing the paging on zero records), and then we call the paging function, written at the top of this tutorial. We pass it the limit, the total rows from the database, and tell it which segment we are using as the page number, and it does the rest, spitting back a div with paged links inside. All that’s left now is to display the links in the view.

Your View:

< ? if(isset($paging)) { print $paging; } ?>

That’s all there is to it. The CodeIgniter paging class is fairly simple to use on its own, but with a small function we can make it just a little bit easier. Isn’t that what everybody wants?

This tutorial assumes a basic working knowledge of Code Igniter. If you have never used CI before, please refer to the framework documentation

In the old days (2 years ago), working the Javascript magic to create a cool AJAX based event took a fairly decent working knowledge of the mechanisms behind the process. With the increasing popularity of Javascript libraries however, this type of functionality became available to the web site hobbyist, and was made much easier for the web site professional.

The following step-by-step tutorial will show you how to combine the power of JQuery (a javascript library that weighs in at about 20k) with Code Igniter (a PHP framework based on the MVC design pattern) to quickly and painlessly pass a record ID through the javascript and over to the server, where it will be passed to a mysql database, used to retrieve some data, and sent back to the page for display.

Step 1
We begin by assuming that you have a div with an id of content, which is where you would like your freshly retrieved data to display, once it has been freshly retrieved. For this exercise, you have already taken an action to call your javascript function with a record ID parameter.

The first thing you need to do, is make sure JQuery is being loaded, and to create a function for your AJAX request.

Step 2:
Next, youll use the JQuery function load, and attach it to your content div:

function get_record_id(record_id) {
     $('#content').load()
}

Step 3:
The load function accepts three arguments. The page to be called on the other side of the HTTPRequest, the array to pass through the POST, and a callback function. It looks like this:

function get_record_id(record_id) {
     $('#content').load(/controller/method,p,function(str){

	 });
}

Lets go back to that. Code Igniter URLs are created by calling the name of your controller, followed by the function inside the controller class that will handle your request. If your server does not support mod-rewrite, you may also need to append an index.php to the beginning. The str inside the callback function is the results of your AJAX request. There isnt much use for the str when using the .load function, but it does come in handy using the other JQuery AJAX functions - $.post and $.get, which I assume are self explanatory.

Step 4

var p = {}; //instantiate the array
p[record_id] = record_id //assign your record_id variable to it.

Thats all there is to it. Your final javascript function looks like this:

function get_record_id(record_id) {
     var p = {};
     p[record_id] = record_id
     $('#content').load(/controller/method,p,function(str){

     });
}

Step 5
On the CI side, you have a controller and method setup something like this:

class Controller
{
   function Controller()
   {
       parent::CI;
   }

   function method()
   {
   }
}

The important part is the method() function, as it will contain some of the code we need to make things happen.

Step 6
The first thing you need to do on the CI side is retrieve the value passed through the request object. This is simple enough, using $_POST[record_id]. You also want to load up your database model so you can get the record out of your database. So, well load the database library, and then load the actual model. Then, we want to send the record ID to the database, get the resulting data, and pass it back out to the request. our function starts to look like its doing something useful pretty quickly.

function method()
{
   $record_id = $_POST[record_id];  //set the record ID
   $this->load->library(database); //load the database library to connect to your database
   $this->load->model(records); //inside your system/application/models folder, create a model based on the procedure outlined in the CI documentation
   $results = $this->records->get_record($record_id); //get the record from the database
}

Step 7
At this point, we need to go into our records.php file in the model folder. Since Code Igniter uses a Model-View-Controller structure, database activity, server-side processing, and client-side display should be as separate from one another as possible. You dont NEED to do this for Code Igniter to do its thing, but its good practice.

Inside the records.php file, well create a method called get_record to match the method referenced above. Well use it to get a record by its primary key of ID, put the resulting data into an array, and send it back to the controller, out to the view, and ultimately into the content div we started with.

function get_record($record_id)
{
   $this->db->where(ID,$record_id); //we want the row whose ID matches the value were passing in
   $query = $this->db->get(record_table); //get the table and put it into an object named $query
   $row = $query->row(); //gets the first row of the resulting dataset.  In this case, only 1 row will ever be returned
   $results[record][$row->ID][name] = $row->name; //here, we create a multi-dimensional array holding the returned values based on the key.
   return $results; //send the record back to the controller
}

The trickiest part of this section is the array. It seems pretty complex from here, but youll see soon enough how it breaks down into something more manageable as we go along.

Step 8
Were back to the controller again, and we have one more line to add - this time to pass the resulting data into a view to be formatted and printed to the content div. The whole method() function now looks like this:

function method()
{
   $ID = $_POST[record_id];  //set the record ID
   $this->load->library(database); //load the database library to connect to your database
   $this->load->model(records); //inside your system/application/models folder, create a model based on the procedure outlined in the CI documentation
   $results = $this->records->get_record($record_id); //get the record from the database
   $this->load->view(AJAX_record,$results);
}

Step 9
The AJAX_record.php file should be in your system/application/views folder. Keep in mind, that when you pass an array to a view (in this case the $results array), it will be exploded inside the view. So, the path to your record is now $record, instead of $results[record]. Also inside will be your standard HTML markup, and something like this:

< ?php foreach($record as $id=>$value) { ?>
     The name associated with this record is: < ?php print $value[name];?>
< ?php } ?>

This output is what php is sending to the request object, and is also what gets loaded into the content div. Code Igniter and JQuery make it that easy to dynamically load data using AJAX.