Module 1
Introduction
Learning Objectives
At the end of the module the student is expected to:
• Understand what is codeigniter / CI.
• List the reasons why developers use CI.
• Enumerate the skills needed in using CI.
• Understand the steps in installing CI.
• Understand the MVC web framework and its structure in CI.
Introduction
• Learning and Development in PHP is simple. CodeIgniter – “a powerful PHP
framework with a very small footprint, built for developers who need a simple
and elegant toolkit to create full-featured web applications.” It sounds very
complex but it’s pretty straightforward.
• CodeIgniter is developed by Ellislab and used by millions worldwide. Developers
prefer to use CI for its rapid application development. It has rich and reusable
libraries and class for your website’s foundation.
Why use Codeigniter or CI.
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CI is an application framework
CI is free
CI is light weight
CI is fast
CI uses Model-View-Controller architecture
CI generates Clean URLs
CI is Extensible
CI is thoroughly documented
CI has a friendly community of users
Skills needed
• The following are the items you need to know before starting to play around CI.
• PHP – A good understanding of the PHP language is a must. As long as you
can perform simple instructions (e.g. variable declaration/assignments,
conditions, loops), you will nearly understand everything here since the
CodeIgniter is made up of PHP!
• HTML – Well, you do need those html elements to manipulate to. You’ll use
this for the layout design, inputs and presentation of data.
Skills needed
• CSS – It’s good if you know Cascading Style Sheets (CSS), and even better if
you’re using external style sheets. There are more web design processors
available if you want to level-up your knowledge on styling however if you don’t
know how, still, you can learn CI.
• MySQL – This means your SQL Basic queries are required. There will some
modules on this book where you need to manipulate I/O (inputs and outputs)
from your data storage or your database. Models communicate with the
database and uses your fundamental knowledge on SQL.
• JavaScript – It makes the website interact with the HTML elements. If you do
not know JS, maybe learn it sometime, okay? You need these for future
developments.
CI Installation
• Step 1. Visit its website on https://www.codeigniter.com/
CI Installation
• Step 2. Find your way to the Download link and click Download.
CI Installation
• Step 3. Extract the downloaded .zip file and place it on your local
server.
CI Installation
• Step 4. If you can see this Welcome Message. Your installation was a
success!
MVC Web Framework
MVC
MVC
• Controller – This contains the Business logic (Business Logic Layer). The
controller controls the Model and View. A controller is a class that contains
methods that decides what to call, or perform and display.
• When a user sends a request on a browser, the controller will determine
the process and perform tasks based on its method; it includes calling a
method returning a value from a model, displaying and passing values on
a view or showing a 404 error page.
MVC
• Views – The Presentation layer. This contains designs, layouts or
templates. It is the collection of what will show up on your browser. The
view is where the user sees and interacts with.
• Models – It is also referred as the Data Access Layer. The Model
communicates with your database. It comprises of methods that execute
queries using the CodeIgniter’s Active Record pattern.
CI Directory
• Basically, CodeIgniter has 3 main folders: Application, System and User
Guide.
• You will work with your website in Application Folder.
• The System folder, keep it a habit to avoid making changes to any of the
files inside. It contains the CodeIgniter’s core files which is necessary to
make it run.
• User_Guide contains the offline documentations you need in developing
with websites in CI.
CI Directory
CI Directory
• Cache: This directory will contain all kinds of cached files if you are
using so. However, you will may need to provide write access for the
application to this directory as codeigniter will need to create temporary
files on this folder. To know how to use caching, please refer to
CodeIgniter caching tutorial.
• Config: This directory includes settings/configuration related
information like database settings, route information, constants
declaration, items to be auto loaded etc.
• Controller: This directory includes all controller definitions. It can be
said as the entry point of application also, every requests triggers a
certain method of a controller.
CI Directory
• Core : If we need to extend the functionality of any core classes like
controller, loader, router etc, then we can declare new class here which will
extend those core classes and put the implementation inside those.
• Errors: This directory includes some basic template for showing various
kind of errors like db error, php errors, 404 errors etc, which we can
change later as per our requirements.
• Helpers: This directory will include all helper files.
• Hooks: This directory will include all hooks declaration.
• Language: This directory will include language files. By loading different
language files, we can make our application multilingual supported
CI Directory
• Libraries: This directory will include all library class files that might
need to be created for our applications.
• Logs: This directory will include all application logs. TO know how to
write log for debug/error/info, please more about error handling
• Migrations: This directory will include migration helpers.
• Models: This directory will include all model classes used in our
application. This section can be said as the ‘data access layer’ of our
application.
• Third_party : This directory will include library files, but only those,
which are imported from third-party. So, difference between the
‘third_party’ and ‘libraries’ is that, one is for self-made libraries, for app
specific, other one is for importing party libraries.
• Views : This directory will include all view template files.
Thank you…