CodeIgniter 3 Sessions

CI sessions are an alternative to php sessions. It is advised to autoload the sessions so they are always available. CI sessions simplify using native php sessions, ie the $_SESSION superglobal. For example, there is no need to include the session_start() function (to start a new or resume an existing session). Session data is simply an array, associated with a particular session ID (cookie).

As well as read, set and unset values, CI also provides 2 special types of session data, flashdata and tempdata.

To read a session variable use either $_SESSION['item_key_name'] (or the magic getter) $this->session->item_key_name

To retrieve all of the existing userdata, you can simply omit the item key $_SESSION for example print_r($_SESSION) (the magic getter only works for properties).

You can assign (set) data to the $_SESSION array, as with any other variable. Or as a property of $this->session. For example $_SESSION['something'] = 'hello' or $this->session->something = 'hello'

Check if a session variable exists: isset($_SESSION['some_name'])

To remove session variables, use for example, unset($_SESSION['some_name']) or multiple values: unset($_SESSION['some_name'], $_SESSION['another_name'])

Session Flashdata

Flashdata is data that will only be available for the next request, and is then automatically cleared. This can be very useful, especially for one-time informational, error or status messages. To create a session variable as flashdata:

$_SESSION['item'] = 'value';
$this->session->mark_as_flash('item');

Or more concisely:

$this->session->set_flashdata('item', 'value');

Read flashdata variables the same way as regular session data $_SESSION['item']

However, if you want to be sure that you’re reading “flashdata” (and not any other kind), you can also use the flashdata() method:

$this->session->flashdata('item');

Or to get an array with all flashdata, simply omit the key parameter:

$this->session->flashdata();

If you find that you need to preserve a flashdata variable through an additional request, you can do so using the keep_flashdata() method.

$this->session->keep_flashdata('item');

Tempdata

Tempdata is session data with a specific expiration time. To mark an existing item as tempdata, simply pass its key and expiry time (in seconds!) to the mark_as_temp() method:

$_SESSION['item'] = 'value';
$this->session->mark_as_temp('item', 300); // erased after 300 seconds

Or concisely:

$this->session->set_tempdata('item', 'value', 300);

Read tempdata variables the same way as regular session data $_SESSION['item']

Destroying a Session

To clear the current session both of these will work in exactly the same way session_destroy() or $this->session->sess_destroy()

Conclusion

You can still use the native php session functions with the CI session library and for simplicity, I think this is best practice. You then only need to learn the extra CI session methods (ie. flashdata, tempdata). The added bonus to the CI's session library is that you don't have to add session_start() to every file that uses sessions.

CodeIgniter's last_query()

I had an issue running codeigniter's $this->db->last_query().

It returns the last query that was run (the query string, not the result). But, remember to run the query, ie call the get() method before the last_query() method.

Example

// Some query you are having trouble building...
$this->db->select('a_column');
$this->db->from('your_table');
// note, you have to call get()
$query = $this->db->get();
echo $this->db->last_query(); // output the converted MySQL query 

This method is helpful when having trouble building queries with the CI query class.

Running CodeIgniter in Heroku

Note: This does not include a database setup.

Grab a copy of the latest codeigniter and navigate to the root folder

cd diylingo/CodeIgniter-3.1.3/

Login to heroku

heroku login

Add git

git init

Identify heroku as the remote repository for git to use

heroku create diylingo

In codeigniter, open config.php and add the heroku address outputted from the create command to

$config['base_url'] = 'https://diylingo.herokuapp.com/';

Because this will be detected as a php app and there is a composer.lock file which demands you satisfy all dependencies, you'll need to run

composer update

Now prepare the files for upload

git add .

git commit -m "initial commit"

Push your code to the remote heroku git repository

git push heroku master

Check the result

open heroku

You should have the CodeIgniter welcome page opened for you in the browser.

Getting started with pagination in CodeIgniter

Intro

Sometimes your database can return a lot of data. Like hundreds (or even thousands) of rows that may need to be outputted to the user. In these kinds of situations, it’s good to use pagination, which codeigniter has an built-in library for.

Pagination is the process of dividing this data into chunks, like pages in a book. On your webpage, this often looks like a series of clickable number links, but can also be formatted to just previous and next links. Behind the scenes though, pagination works with SQL’s LIMIT and OFFSET clauses. These two clauses in essence specify a range of results (database rows) to output.

In CodeIgniter, the pagination library takes care of figuring out how many pagination links are required, and inserts the OFFSET clause value as a method argument to the controller method you are calling it from. Here is an example of just one pagination link

<a href="/language/read/20" data-ci-pagination-page="2">2</a>

How to do it

Here is how I attempted to use pagination.

Controller

public function read($pagination_offset = 0)
{
  $this->load->library('pagination');
  $pagination_config['base_url'] = base_url('language/read'); // the controller you are calling
  $pagination_config['per_page'] = 20; // sql query LIMIT number

  $this->data['languages'] = $this->language_model->get_languages($pagination_config['per_page'], $pagination_offset); // your database call with LIMIT and OFFSET arguments
  $total_query_rows = $this->db->query('SELECT id FROM languages')->num_rows(); // what the database would have yielded without the LIMIT and OFFSET clauses (*see Notes)

  $pagination_config['total_rows'] = $total_query_rows;
  $this->pagination->initialize($pagination_config); // prepares the pagination based on your configurations

  $this->data['pagination'] = $this->pagination->create_links(); // outputs the pagination as a string (*see Notes)
  $this->load->view('language', $data);
}

Model

public function get_languages($limit, $pagination_offset)
{
  $query = $this->db->query("
  SELECT
    languages.id AS id,
    languages.title AS language,
    country_code,
    COUNT(courses.id) AS number_of_courses
  FROM languages
  LEFT JOIN courses
  ON languages.id = courses.language_id
  GROUP BY languages.title
  LIMIT $limit OFFSET $pagination_offset
  ");
  return $query->result();
}

Notes

The three most important things here are

• $pagination_config['base_url'] the controller method to call.
• $pagination_config['per_page'] the SQL LIMIT or how many results per page you want to see.
• $pagination_config['total_query_rows'] all the rows in the results set, so the pagination library can figure out how many links to create.

In $total_query_rows instead of writing the whole query without LIMIT and OFFSET, I wrote a much simpler one because I knew it would return the same number of rows every time.

If there is no pagination to show, create_links() will output an empty string.

In the model, you can of course use the query class library to pass LIMIT and OFFSET clauses.

Changing the view output

Above is the minimum you need to get pagination working, but it’s likely you will want to style or customise your output. To do this you can edit the default preferences which are passed to the initialize() function. I prefer to do this by creating a pagination.php file in the config folder. Here is an example using the W3.CSS front-end CSS framework

pagination.php

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

$config['full_tag_open'] = '<ul class="w3-pagination w3-border w3-light-grey">';
$config['full_tag_close'] = '</ul>';

$config['first_link'] = 'First'; // might require more than 5 pages by default to show up
$config['first_tag_open'] = '<li>';
$config['first_tag_close'] = '</li>';
// $config['first_url'] = ''; // An alternative URL to use for the “first page” link.

$config['last_link'] = 'Last';
$config['last_tag_open'] = '<li>';
$config['last_tag_close'] = '</li>';

$config['next_link'] = '&raquo;';
$config['next_tag_open'] = '<li>';
$config['next_tag_close'] = '</li>';

$config['prev_link'] = '&laquo;';
$config['prev_tag_open'] = '<li>';
$config['prev_tag_close'] = '</li>';

$config['cur_tag_open'] = '<li><b><a class="w3-green">';
$config['cur_tag_close'] = '</a></b></li>';

$config['num_tag_open'] = '<li>';
$config['num_tag_close'] = '</li>';

View

<?php if (!empty($pagination)): ?>
  <div class="w3-container">
    <div class="w3-card-2 w3-padding w3-light-grey">
      <?php echo $pagination; ?>
    </div>
  </div>
<?php endif; ?>

Creating backups of database rows

I came across a situation where I needed to make a backup of every row either newley insterted, or updated in my database. I didn’t want to share the latest backed up data on the same table, but then needed a way to reference the pk id of the original row when the data from that row was created for the first time.

MySQL has a handy function called LAST_INSERT_ID() which get’s the last inserted row id just executed. CodeIgniter also has a very easy way to get this value $this->db->insert_id();, which can be assigned to a variable and used with an insert statement, to create a reference to the backup of the new row in the backup table. You'll probably also want to do this under a table lock to prevent concurrent operations.

I don’t know whether this is the best way to do backups. This is just something I came up with. I should probably lookup how others do it at some point :P

Resolving issues using Google's smtp email with Codeigniter

So this took me days to figure out, so hence a blog-post.

I’ve been looking for an easy way to test apps that use email locally. Using an online smtp service like gmail is in my opinion, much easier than setting up a local mail server. The natural choice for me was gmail since I have already created some test accounts for development there (It’s best not to mix personal and dev accounts for reasons which will be apparent later on). However, I did run into a couple of issues trying this with CodeIgniter.

Issue 1.

With your dev account open, go here and turn on access for less secure apps. Thanks to http://www.wpsitecare.com/gmail-smtp-settings/ for that.

Issue 2.

After loading CodeIgniter’s email library, the following line is essential to send email

$this->email->set_newline("\r\n"); // in the controller

or add the equivalent to the email config file (see example below)

$config['newline'] = "\r\n"; // essential to use double quotes here!!!

(Update: I’ve found more info on that issue here).

After checking off these two points, you can now proceed to send smtp email locally.

Here is a quick example

In application/config, create a file called email.php (it will be automatically recognised by CodeIgniter). Add the following

<?php if(!defined('BASEPATH')) exit('No direct script access allowed');

// SMTP config
$config['mailtype'] = 'html'; // default is text
$config['protocol'] = 'smtp';
$config['charset'] = 'utf-8';
//$config['newline'] = "\r\n"; // essential to use double quotes here!!!
$config['smtp_host'] = 'ssl://smtp.gmail.com';
$config['smtp_port'] = 465;
$config['smtp_user'] = 'your_dev_email@gmail.com';
$config['smtp_pass'] = 'Your_Password';

In your controller, add

$this->load->library('email');
$this->email->set_newline("\r\n"); // will fail without this line!!!

$this->email->from('your_dev_email@gmail.com', 'Your_Name');
$this->email->to('another_dev_email@gmail.com');
$this->email->subject('Email Test');
$this->email->message('Test_mail controller.');

if($this->email->send()){
  $data['message'] = "Mail sent...";
}
else {
    $data['message'] = "Sorry Unable to send email...";
}

$this->load->view('your_view', $data);

Then check the output in your_view by echoing the $message variable, and of course check your email ;)

Issues using Google’s smtp email with Codeigniter

This took me days to figure out, so hence a blog-post.

I’ve been looking for an easy way to test apps that use email locally. Using an online smtp service like gmail is in my opinion, much easier than setting up a local mail server. The natural choice for me was gmail since I have already created some test accounts for development there (It’s best not to mix personal and dev accounts for reasons which will be apparent later on). However, I did run into a couple of issues trying this with CodeIgniter.

Issue 1

With your dev account open, go here https://www.google.com/settings/security/lesssecureapps and turn on access for less secure apps. Thanks to http://www.wpsitecare.com/gmail-smtp-settings/ for that.

Issue 2

After loading CodeIgniter’s email library, the following line is essential to send email

$this->email->set_newline("\r\n"); // in the controller

or add the equivalent to the email config file (see example below)

$config['newline'] = "\r\n"; // essential to use double quotes here!!!

(Update: I’ve found more info on that issue here).

After checking off these two points, you can now proceed to send smtp email locally.

Here is a quick example

In application/config, create a file called email.php (it will be automatically recognised by CodeIgniter). Add the following

<?php if(!defined('BASEPATH')) exit('No direct script access allowed');

// SMTP config
$config['mailtype'] = 'html'; // default is text
$config['protocol'] = 'smtp';
$config['charset'] = 'utf-8';
//$config['newline'] = "\r\n"; // essential to use double quotes here!!!
$config['smtp_host'] = 'ssl://smtp.gmail.com';
$config['smtp_port'] = 465;
$config['smtp_user'] = 'your_dev_email@gmail.com';
$config['smtp_pass'] = 'Your_Password';

In your controller, add

$this->load->library('email');
$this->email->set_newline("\r\n"); // will fail without this line!!!

$this->email->from('your_dev_email@gmail.com', 'Your_Name');
$this->email->to('another_dev_email@gmail.com');
$this->email->subject('Email Test');
$this->email->message('Test_mail controller.');

if($this->email->send()){
  $data['message'] = "Mail sent...";
}
else {
    $data['message'] = "Sorry Unable to send email...";
}

$this->load->view('your_view', $data);

Then check the output in your_view by echoing the $message variable, and of course check your email 😉