codeigniter_tutorial.pdf

August 21, 2017 | Author: raysubha123 | Category: Model–View–Controller, Library (Computing), Web Page, Databases, Computer File
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CodeIgniter

About the Tutorial CodeIgniter is 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. CodeIgniter was created by EllisLab, and is now a project of the British Columbia Institute of Technology.

Audience This tutorial has been prepared for developers who would like to learn the art of developing websites using CodeIgniter. It provides a complete understanding of this framework.

Prerequisites Before you start proceeding with this tutorial, we assume that you are already exposed to HTML, Core PHP, and Advance PHP. We have used CodeIgniter version 3.0.1 in all the examples.

Copyright & Disclaimer Copyright 2015 by Tutorials Point (I) Pvt. Ltd. All the content and graphics published in this e-book are the property of Tutorials Point (I) Pvt. Ltd. The user of this e-book is prohibited to reuse, retain, copy, distribute or republish any contents or a part of contents of this e-book in any manner without written consent of the publisher. We strive to update the contents of our website and tutorials as timely and as precisely as possible, however, the contents may contain inaccuracies or errors. Tutorials Point (I) Pvt. Ltd. provides no guarantee regarding the accuracy, timeliness or completeness of our website or its contents including this tutorial. If you discover any errors on our website or in this tutorial, please notify us at [email protected]

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Table of Contents About the Tutorial .................................................................................................................................... i Audience .................................................................................................................................................. i Prerequisites ............................................................................................................................................ i Copyright & Disclaimer............................................................................................................................. i Table of Contents .................................................................................................................................... ii

1.

CODEIGNITER – OVERVIEW ................................................................................................. 1

2.

INSTALLING CODEIGNITER ................................................................................................... 3

3.

APPLICATION ARCHITECTURE .............................................................................................. 4 Directory Structure.................................................................................................................................. 5

4.

CODEIGNITER – MVC FRAMEWORK..................................................................................... 8

5.

CODEIGNITER – BASIC CONCEPTS........................................................................................ 9 Controllers .............................................................................................................................................. 9 Views .................................................................................................................................................... 11 Models .................................................................................................................................................. 13 Helpers .................................................................................................................................................. 15 Routing ................................................................................................................................................. 16

6.

CODEIGNITER – CONFIGURATION ..................................................................................... 19 Configuring Base URL ............................................................................................................................ 19 Database Configuration......................................................................................................................... 19 Autoload Configuration ......................................................................................................................... 21

7.

WORKING WITH DATABASE ............................................................................................... 23 Connecting to a Database ..................................................................................................................... 23 Inserting a Record ................................................................................................................................. 23 ii

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Updating a Record................................................................................................................................. 24 Deleting a Record .................................................................................................................................. 25 Selecting a Record ................................................................................................................................. 26 Closing a Connection ............................................................................................................................. 26 Example ................................................................................................................................................ 26

8.

CODEIGNITER – LIBRARIES ................................................................................................. 33 Library Classes ....................................................................................................................................... 33 Creating Libraries .................................................................................................................................. 34

9.

ERROR HANDLING ............................................................................................................. 37

10. FILE UPLOADING................................................................................................................ 39 11. SENDING EMAIL................................................................................................................. 43 12. FORM VALIDATION ............................................................................................................ 49 13. SESSION MANAGEMENT.................................................................................................... 55 14. FLASHDATA ....................................................................................................................... 58 15. TEMPDATA ........................................................................................................................ 61 16. COOKIE MANAGEMENT ..................................................................................................... 65 17. COMMON FUNCTIONS ...................................................................................................... 68 18. PAGE CACHING .................................................................................................................. 71 19. PAGE REDIRECTION ........................................................................................................... 73 20. APPLICATION PROFILING ................................................................................................... 75 21. BENCHMARKING ............................................................................................................... 77 22. ADDING JS AND CSS........................................................................................................... 80 iii

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23. INTERNATIONALIZATION ................................................................................................... 83 24. CODEIGNITER – SECURITY ................................................................................................. 88 XSS Prevention ...................................................................................................................................... 88 SQL Injection Prevention ....................................................................................................................... 88 Hiding PHP Errors .................................................................................................................................. 89 CSRF Prevention .................................................................................................................................... 90 Password Handling ................................................................................................................................ 90

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1. CodeIgniter – Overview

CodeIgniter

CodeIgniter is an application development framework, which can be used to develop websites, using PHP. It is an Open Source framework. It has a very rich set of functionality, which will increase the speed of website development work. If you know PHP well, then CodeIgniter will make your task easier. It has a very rich set of libraries and helpers. By using CodeIgniter, you will save a lot of time, if you are developing a website from scratch. Not only that, a website built in CodeIgniter is secure too, as it has the ability to prevent various attacks that take place through websites.

CodeIgniter Features Some of the important features of CodeIgniter are listed below: 

Model-View-Controller Based System



Extremely Light Weight



Full Featured database classes with support for several platforms.



Query Builder Database Support



Form and Data Validation



Security and XSS Filtering



Session Management



Email Sending Class. Supports Attachments, HTML/Text email, multiple protocols (sendmail, SMTP, and Mail) and more.



Image Manipulation Library (cropping, resizing, rotating, etc.). Supports GD, ImageMagick, and NetPBM



File Uploading Class



FTP Class



Localization



Pagination



Data Encryption



Benchmarking



Full Page Caching



Error Logging



Application Profiling



Calendaring Class



User Agent Class



Zip Encoding Class 1

CodeIgniter



Template Engine Class



Trackback Class



XML-RPC Library



Unit Testing Class



Search-engine Friendly URLs



Flexible URI Routing



Support for Hooks and Class Extensions



Large library of “helper” functions

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2. Installing CodeIgniter

CodeIgniter

It is very easy to install CodeIgniter. Just follow the steps given below: 

Step-1: Download the CodeIgniter from the link http://www.codeigniter.com/download



Step-2: Unzip the folder.



Step-3: Upload all files and folders to your server.



Step-4: After uploading all the files to your server, visit the URL of your server, e.g., www.domain-name.com.

On visiting the URL, you will see the following screen:

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3. Application Architecture

CodeIgniter

The architecture of CodeIgniter application is shown below.

Figure: CodeIgniter Application Flowchart



As shown in the figure, whenever a request comes to CodeIgniter, it will first go to index.php page.



In the second step, Routing will decide whether to pass this request to step-3 for caching or to pass this request to step-4 for security check.



If the requested page is already in Caching, then Routing will pass the request to step-3 and the response will go back to the user.



If the requested page does not exist in Caching, then Routing will pass the requested page to step-4 for Security checks.



Before passing the request to Application Controller, the Security of the submitted data is checked. After the Security check, the Application Controller loads necessary Models, Libraries, Helpers, Plugins and Scripts and pass it on to View.



The View will render the page with available data and pass it on for Caching. As the requested page was not cached before so this time it will be cached in Caching, to process this page quickly for future requests.

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Directory Structure The image given below shows the directory structure of the CodeIgniter.

Figure: Directory Structure

CodeIgniter directory structure is divided into 3 folders: 

Application



System



User_guide

Application As the name indicates the Application folder contains all the code of your application that you are building. This is the folder where you will develop your project. The Application folder contains several other folders, which are explained below: 

Cache: This folder contains all the cached pages of your application. These cached pages will increase the overall speed of accessing the pages.



Config: This folder contains various files to configure the application. With the help of config.php file, user can configure the application. Using database.php file, user can configure the database of the application.



Controllers: This folder holds the controllers of your application. It is the basic part of your application.



Core: This folder will contain base class of your application.



Helpers: In this folder, you can put helper class of your application. 5

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Hooks: The files in this folder provide a means to tap into and modify the inner workings of the framework without hacking the core files.



Language: This folder contains language related files.



Libraries: This folder contains files of the libraries developed for your application.



Logs: This folder contains files related to the log of the system.



Models: The database login will be placed in this folder.



Third_party: In this folder, you can place any plugins, which will be used for your application.



Views: Application’s HTML files will be placed in this folder.

System This folder contains CodeIgniter core codes, libraries, helpers and other files, which help make the coding easy. These libraries and helpers are loaded and used in web app development. This folder contains all the CodeIgniter code of consequence, organized into various folders: 

Core: This folder contains CodeIgniter’s core class. Do not modify anything here. All of your work will take place in the application folder. Even if your intent is to extend the CodeIgniter core, you have to do it with hooks, and hooks live in the application folder.



Database: The database folder contains core database drivers and other database utilities.



Fonts: The fonts folder contains font related information and utilities.



Helpers: The helpers folder contains standard CodeIgniter helpers (such as date, cookie, and URL helpers).



Language: The language folder contains language files. You can ignore it for now.



Libraries: The libraries folder contains standard CodeIgniter libraries (to help you with e-mail, calendars, file uploads, and more). You can create your own libraries or extend (and even replace) standard ones, but those will be saved in the application/libraries directory to keep them separate from the standard CodeIgniter libraries saved in this particular folder.

User_guide This is your user guide to CodeIgniter. It is basically, the offline version of user guide on CodeIgniter website. Using this, one can learn the functions of various libraries, helpers 6

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and classes. It is recommended to go through this user guide before building your first web app in CodeIgniter. Beside these three folders, there is one more important file named “index.php”. In this file, we can set the application environment and error level and we can define system and application folder name. It is recommended, not to edit these settings if you do not have enough knowledge about what you are going to do.

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4. CodeIgniter – MVC Framework

CodeIgniter is based on the Model-View-Controller (MVC) development pattern. MVC is a software approach that separates application logic from presentation. In practice, it permits your web pages to contain minimal scripting since the presentation is separate from the PHP scripting.

Figure: CodeIgniter – MVC Framework 

The Model represents your data structures. Typically, your model classes will contain functions that help you retrieve, insert and update information in your database.



The View is information that is being presented to a user. A View will normally be a web page, but in CodeIgniter, a view can also be a page fragment like a header or footer. It can also be an RSS page, or any other type of “page”.



The Controller serves as an intermediary between the Model, the View, and any other resources needed to process the HTTP request and generate a web page.

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5. CodeIgniter – Basic Concepts

CodeIgniter

Controllers A controller is a simple class file. As the name suggests, it controls the whole application by URI.

Creating a Controller First, go to application/controllers folder. You will find two files there, index.html and Welcome.php. These files come with the CodeIgniter. Keep these files as they are. Create a new file under the same path named “Test.php”. Write the following code in that file: The Test class extends an in-built class called CI_Controller. This class must be extended whenever you want to make your own Controller class.

Calling a Controller The above controller can be called by URI as follows: http://www.your-domain.com/index.php/test Notice the word “test” in the above URI after index.php. This indicates the class name of controller. As we have given the name of the controller “Test”, we are writing “test” after the index.php. The class name must start with uppercase letter but we need to write lowercase letter when we call that controller by URI. The general syntax for calling the controller is as follows: http://www.your-domain.com/index.php/controller/method-name

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Creating & Calling Constructor Method Let us modify the above class and create another method named “hello”. We can execute the above controller in the following three ways: 1. http://www.your-domain.com/index.php/test 2. http://www.your-domain.com/index.php/test/index 3. http://www.your-domain.com/index.php/test/hello After visiting the first URI in the browser, we get the output as shown in the picture given below. As you can see, we got the output of the method “index”, even though we did not pass the name of the method the URI. We have used only controller name in the URI. In such situations, the CodeIgniter calls the default method “index”.

Visiting the second URI in the browser, we get the same output as shown in the above picture. Here, we have passed method’s name after controller’s name in the URI. As the name of the method is “index”, we are getting the same output.

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Visiting the third URI in the browser, we get the output as shown in picture given below. As you can see, we are getting the output of the method “hello” because we have passed “hello” as the method name, after the name of the controller “test” in the URI.

Points to Remember: 

The name of the controller class must start with an uppercase letter.



The controller must be called with lowercase letter.



Do not use the same name of the method as your parent class, as it will override parent class’s functionality.

Views This can be a simple or complex webpage, which can be called by the controller. The webpage may contain header, footer, sidebar etc. View cannot be called directly. Let us create a simple view. Create a new file under application/views with name “test.php” and copy the below given code in that file. CodeIgniter View Example CodeIgniter View Example

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CodeIgniter

Change the code of application/controllers/test.php file as shown in the below.

Loading the View The view can be loaded by the following syntax: $this->load->view('name'); Where name is the view file, which is being rendered. If you have planned to store the view file in some directory then you can use the following syntax: $this->load->view('directory-name/name'); It is not necessary to specify the extension as php, unless something other than .php is used. The index() method is calling the view method and passing the “test” as argument to view() method because we have stored the html coding in “test.php” file under application/views/test.php. Here is the output of the above code:

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The following flowchart illustrates of how everything works:

http://www.your-domain.com/index.php/test The above URI will first call the index.php file in your CodeIgniter folder.

Controller The index.php file will call the class application/controllers/Test.php. As the method name hasn't been passed in the URI, the default index() method will be called which will indirectly call the application/views/test.php file.

Views $this->load->view('test') will render the view file application/views/test.php and generates the output.

Models Models classes are designed to work with information in the database. As an example, if you are using CodeIgniter to manage users in your application then you must have model class, which contains functions to insert, delete, update and retrieve your users’ data.

Creating Model Class Model classes are stored in application/models directory. Following code shows how to create model class in CodeIgniter. 13

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Where Model_name is the name of the model class that you want to give. Each model class must inherit the CodeIgniter’s CI_Model class. The first letter of the model class must be in capital letter. Following is the code for users’ model class. The above model class must be saved as User_model.php. The class name and file name must be same.

Loading Model Model can be called in controller. Following code can be used to load any model. $this->load->model('model_name'); Where model_name is the name of the model to be loaded. After loading the model you can simply call its method as shown below. $this->model_name->method();

Auto-loading Models There may be situations where you want some model class throughout your application. In such situations, it is better if we autoload it.

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As shown in the above figure, pass the name of the model in the array that you want to autoload and it will be autoloaded, while system is in initialization state and is accessible throughout the application.

Helpers As the name suggests, it will help you build your system. It is divided into small functions to serve different functionality. A number of helpers are available in CodeIgniter, which are listed in the table below. We can build our own helpers too. Helpers are typically stored in your system/helpers, or application/helpers directory. Custom helpers are stored in application/helpers directory and systems’ helpers are stored in system/helpers directory. CodeIgniter will look first in your application/helpers directory. If the directory does not exist or the specified helper is not located, CodeIgniter will instead, look in your global system/helpers/ directory. Each helper, whether it is custom or system helper, must be loaded before using it. Helper Name Array Helper CAPTCHA Helper Cookie Helper Date Helper Directory Helper Download Helper Email Helper File Helper Form Helper HTML Helper Inflector Helper Language Helper Number Helper Path Helper Security Helper

Description The Array Helper file contains functions that assist in working with arrays. The CAPTCHA Helper file contains functions that assist in creating CAPTCHA images. The Cookie Helper file contains functions that assist in working with cookies. The Date Helper file contains functions that help you work with dates. The Directory Helper file contains functions that assist in working with directories. The Download Helper lets you download data to your desktop. The Email Helper provides some assistive functions for working with Email. For a more robust email solution, see CodeIgniter’s Email Class. The File Helper file contains functions that assist in working with files. The Form Helper file contains functions that assist in working with forms. The HTML Helper file contains functions that assist in working with HTML. The Inflector Helper file contains functions that permits you to change words to plural, singular, camel case, etc. The Language Helper file contains functions that assist in working with language files. The Number Helper file contains functions that help you work with numeric data. The Path Helper file contains functions that permits you to work with file paths on the server. The Security Helper file contains security related functions. 15

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Smiley Helper String Helper Text Helper Typography Helper URL Helper XML Helper

The Smiley Helper file contains functions that let you manage smileys (emoticons). The String Helper file contains functions that assist in working with strings. The Text Helper file contains functions that assist in working with text. The Typography Helper file contains functions that help your format text in semantically relevant ways. The URL Helper file contains functions that assist in working with URLs. The XML Helper file contains functions that assist in working with XML data.

Loading a Helper A helper can be loaded as shown below: $this->load->helper('name'); Where name is the name of the helper. For example, if you want to load the URL Helper, then it can be loaded as: $this->load->helper('url');

Routing CodeIgniter has user-friendly URI routing system, so that you can easily re-route URL. Typically, there is a one-to-one relationship between a URL string and its corresponding controller class/method. The segments in a URI normally follow this pattern: your-domain.com/class/method/id/ 

The first segment represents the controller class that should be invoked.



The second segment represents the class function, or method, that should be called.



The third, and any additional segments, represent the ID and any variables that will be passed to the controller.

In some situations, you may want to change this default routing mechanism. CodeIgniter provides facility through which you can set your own routing rules.

Customize Routing Rules There is a particular file where you can handle all these. The file is located at application/config/routes.php. You will find an array called $route in which you can customize your routing rules. The key in the $route array will decide what to route and the value will decide where to route. There are three reserved routes in CodeIgniter. 16

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Reserved Routes

$route['default_controller']

This route indicates which controller class should be loaded, if the URI contains no data, which will be the case when people load your root URL. You are encouraged to have a default route otherwise a 404 page will appear, by default. We can set home page of website here so it will be loaded by default.

$route['404_override']

This route indicates which controller class should be loaded if the requested controller is not found. It will override the default 404 error page. It won’t affect to the show_404() function, which will continue loading the default error_404.php file in application/views/errors/error_404.php.

$route['translate_uri_dashes']

As evident by the Boolean value, this is not exactly a route. This option enables you to automatically replace dashes (‘-‘) with underscores in the controller and method URI segments, thus saving you additional route entries if you need to do that. This is required because the dash is not a valid class or method-name character and will cause a fatal error, if you try to use it.

Routes can be customized by wildcards or by using regular expressions but keep in mind that these customized rules for routing must come after the reserved rules.

Wildcards We can use two wildcard characters as explained below: 

(:num) – It will match a segment containing only numbers.



(:any) – It will match a segment containing any character.

Example $route['product/:num']='catalog/product_lookup'; In the above example, if the literal word “product” is found in the first segment of the URL, and a number is found in the second segment, the “catalog” class and the “product_lookup” method are used instead.

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Regular Expressions Like wildcards, we can also use regular expressions in $route array key part. If any URI matches with regular expression, then it will be routed to the value part set into $route array. Example $route['products/([a-z]+)/(\d+)']='$1/id_$2'; In the above example, a URI similar to products/shoes/123 would instead call the “shoes” controller class and the “id_123” method.

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6. CodeIgniter – Configuration

CodeIgniter

After setting up the site, the next thing that we should do is to configure the site. The application/config folder contains a group of files that set basic configuration of your site.

Configuring Base URL The base URL of the site can be configured in application/config/config.php file. It is URL to your CodeIgniter root. Typically, this will be your base URL, with a trailing slash e.g. http://example.com/ If this is not set, then CodeIgniter will try to guess the protocol, domain and path to your installation. However, you should always configure this explicitly and never rely on autoguessing, especially in production environments. You can configure the base URL in the $config array with key “base_url” as shown below: $config['base_url'] = 'http://your-domain.com';

Database Configuration The database of the site can be configured in application/database.php file. Often we need to set up database for different environment like development and production. With the multidimensional array provided in the CodeIgniter, we can setup database for different environment. The configuration settings are stored in the array as shown below: $db['default'] = array( 'dsn'

=> '',

'hostname' => 'localhost', 'username' => 'root', 'password' => '', 'database' => 'database_name', 'dbdriver' => 'mysqli', 'dbprefix' => '', 'pconnect' => TRUE, 'db_debug' => TRUE, 'cache_on' => FALSE, 'cachedir' => '', 'char_set' => 'utf8', 'dbcollat' => 'utf8_general_ci', 19

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'swap_pre' => '', 'encrypt' => FALSE, 'compress' => FALSE, 'stricton' => FALSE, 'failover' => array() ); You can leave few options to their default values except hostname, username, password, database and dbdriver. 

hostname:

Specify location of your database here e.g. localhost or IP address



username:

Set username of your database here.



password:

Set password of your database here.



database:

Set name of the database here.



dbdriver:

Set type of database that you are using e.g. MySQL, MySQLi,

Postgre SQL, ODBC, and MS SQL. By changing the key of the array $db, you can set other configuration of database as shown below. Here, we have set the key to ‘test’ to set the database for testing environment, by keeping the other database environment as it is. $db['test'] = array( 'dsn'

=> '',

'hostname' => 'localhost', 'username' => 'root', 'password' => '', 'database' => 'database_name', 'dbdriver' => 'mysqli', 'dbprefix' => '', 'pconnect' => TRUE, 'db_debug' => TRUE, 'cache_on' => FALSE, 'cachedir' => '', 'char_set' => 'utf8', 'dbcollat' => 'utf8_general_ci', 'swap_pre' => '', 'encrypt' => FALSE, 'compress' => FALSE, 'stricton' => FALSE, 'failover' => array() 20

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);

You can simply switch to different environment by changing the value of a variable as shown below: $active_group = ‘default’; //This will set the default environment $active_group = ‘test’; //This will set the test environment

Autoload Configuration This file specifies, by default, which systems should be loaded. In order to keep the framework as light-weight as possible, only the absolute minimal resources are loaded by default. One should autoload the frequently used system, rather than loading it at local level, repeatedly. Following are the things you can load automatically: 

Libraries: It is a list of libraries, which should be auto loaded. Provide a list of libraries in an array as shown below to be autoloaded by CodeIgniter. In this example, we are auto loading database, email and session libraries. $autoload['libraries'] = array('database', 'email', 'session');



Drivers: These classes are located in system/libraries/ or in your application/libraries/ directory, but are also placed inside their own subdirectory and they extend the CI_Driver_Library class. They offer multiple interchangeable driver options. Following is an example to autoload cache drivers. $autoload['drivers'] = array('cache');



Helper files: It is a list of helper files, to be autoloaded. Provide a list of libraries in the array, as shown below, to be autoloaded by CodeIgniter. In the given example, we are autoloading URL and file helpers. $autoload['helper'] = array('url', 'file');



Custom config files: These files are intended for use, only if you have created custom config files. Otherwise, leave it blank. Following is an example of how to autoload more than one config files. $autoload['config'] = array('config1', 'config2');



Language files: It is a list of language files, which should be auto loaded. Look at the example given below. Provide a list of languages in an array as shown below to be auto loaded by CodeIgniter. Keep in mind that do not include the "_lang" part of your file. For example, "codeigniter_lang.php" would be referenced as array('codeigniter'); 21

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$autoload['language'] = array('lang1', 'lang2');



Models: It is a list of models file, which should be autoloaded. Provide a list of models in an array as shown below to be autoloaded by CodeIgniter. Following is the example of how to auto load more than one models files. $autoload['model'] = array('first_model', 'second_model');

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7. Working with Database

CodeIgniter

Like any other framework, we need to interact with the database very often and CodeIgniter makes this job easy for us. It provides rich set of functionalities to interact with database. In this section, we will understand how the CRUD (Create, Read, Update, Delete) functions work with CodeIgniter. We will use stud table to select, update, delete, and insert the data in stud table. Table Name: stud int(11) varchar(30)

roll_no Name

Connecting to a Database We can connect to database in the following two way:. 

Automatic Connecting: Automatic connection can be done by using the file application/config/autoload.php. Automatic connection will load the database for each and every page. We just need to add the database library as shown below: $autoload['libraries'] = array(‘library’);



Manual Connecting: If you want database connectivity for only some of the pages, then we can go for manual connecting. We can connect to database manually by adding the following line in any class. $this->load->database();

Here, we are not passing any argument because everything is set in the database config file application/config/database.php

Inserting a Record To insert a record in the database, the insert() function is used as shown in the following table: Syntax

insert([$table = ''[, $set = NULL[, $escape = NULL]]]) 

$table (string) – Table name



$set (array) – An associative array of field/value pairs



$escape (bool) – Whether to escape values and identifiers

Parameters

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Returns Return Type

TRUE on success, FALSE on failure bool

The following example shows how to insert a record in stud table. The $data is an array in which we have set the data and to insert this data to the table stud, we just need to pass this array to the insert function in the 2nd argument. $data = array( 'roll_no' => ‘1’, 'name' => ‘Virat’ ); $this->db->insert("stud", $data);

Updating a Record To update a record in the database, the update() function is used along with set() and where() functions as shown in the tables below. The set() function will set the data to be updated. Syntax

Parameters

Returns Return Type

set($key[, $value = ''[, $escape = NULL]]) 

$key (mixed) – Field name, or an array of field/value pairs



$value (string) – Field value, if $key is a single field



$escape (bool) – Whether to escape values and identifiers

CI_DB_query_builder instance (method chaining) CI_DB_query_builder

The where() function will decide which record to update. Syntax

Parameters

Returns Return Type

where($key[, $value = NULL[, $escape = NULL]]) 

$key (mixed) – Name of field to compare, or associative array



$value (mixed) – If a single key, compared to this value



$escape (bool) – Whether to escape values and identifiers

DB_query_builder instance object

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Finally, the update() function will update data in the database. Syntax

update([$table = ''[, $set = NULL[, $where = NULL[, $limit = NULL]]]]) 

$table (string) – Table name



$set (array) – An associative array of field/value pairs



$where (string) – The WHERE clause



$limit (int) – The LIMIT clause

Parameters

Returns Return Type

TRUE on success, FALSE on failure bool

$data = array( 'roll_no' => ‘1’, 'name' => ‘Virat’ ); $this->db->set($data); $this->db->where("roll_no", ‘1’); $this->db->update("stud", $data);

Deleting a Record To delete a record in the database, the delete() function is used as shown in the following table: Syntax

Parameters

Returns Return Type

delete([$table = ''[, $where $reset_data = TRUE]]]])

=

''[,

$limit

=

NULL[,



$table (mixed) – The table(s) to delete from; string or array



$where (string) – The WHERE clause



$limit (int) – The LIMIT clause



$reset_data (bool) – TRUE to reset the query “write” clause

CI_DB_query_builder instance (method chaining) or FALSE on failure mixed

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CodeIgniter

Use the following code to to delete a record in the stud table. The first argument indicates the name of the table to delete record and the second argument decides which record to delete. $this->db->delete("stud", "roll_no = 1");

Selecting a Record To select a record in the database, the get function is used, as shown in the following table: Syntax

get([$table   

Parameters Returns Return Type

= ''[, $limit = NULL[, $offset = NULL]]]) $table (string) – The table to query $limit (int) – The LIMIT clause $offset (int) – The OFFSET clause

CI_DB_result instance (method chaining) CI_DB_result

Use the following code to get all the records from the database. The first statement fetches all the records from “stud” table and returns the object, which will be stored in $query object. The second statement calls the result() function with $query object to get all the records as array. $query = $this->db->get("stud"); $data['records'] = $query->result();

Closing a Connection Database connection can be closed manually, by executing the following code: $this->db->close();

Example Create a controller class called Stud_controller.php application/controller/Stud_controller.php

and

save

it

at

Here is a complete example, wherein all of the above-mentioned operations are performed. Before executing the following example, create a database and table as instructed at the starting of this chapter and make necessary changes in the database config file stored at application/config/database.php

Create a model class called application/models/Stud_Model.php

Stud_Model.php

and

save

it

in



Create a view file called application/views/Stud_add.php

Stud_add.php

and

save

it

in

Students Example



Create a view file called application/views/Stud_edit.php

Stud_edit.php

and

save

it

in

Students Example

Create a view file called application/views/Stud_view.php

Stud_view.php

and

save

it

in

Students Example Copy the code given below and store it at application/view/Upload_success.php Upload Form

Your file was successfully uploaded!

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CodeIgniter

:



Copy the code given below and store it at application/controllers/Upload.php. Create “uploads” folder at the root of CodeIgniter i.e. at the parent directory of application folder. Make the following change in the route file in application/config/routes.php and add the following line at the end of file. $route['upload'] = 'Upload'; Now let us execute this example by visiting the following URL in the browser. Replace the yoursite.com with your URL. http://yoursite.com/index.php/upload It will produce the following screen:

Figure: Upload Form

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CodeIgniter

After successfully uploading a file, you will see the following screen:

Figure: File successfully uploaded

42

11. Sending Email

CodeIgniter

Sending email in CodeIgniter is much easier. You also configure the preferences regarding email in CodeIgniter. CodeIgniter provides following features for sending emails: 

Multiple Protocols: Mail, Sendmail, and SMTP



TLS and SSL Encryption for SMTP



Multiple recipients



CC and BCCs



HTML or Plaintext email



Attachments



Word wrapping



Priorities



BCC Batch Mode, enabling large email lists to be broken into small BCC batches.



Email Debugging tools

Email class has the following functions to simplify the job of sending emails. Syntax

Parameters

Return Return type

Syntax

Parameters

Return Return type Syntax Parameters

from($from[, $name = ''[, $return_path = NULL]]) 

$from (string) – “From” e-mail address



$name (string) – “From” display name



$return_path (string) – Optional email address to redirect undelivered e-mail to

CI_Email instance (method chaining) CI_Email

reply_to($replyto[, $name = '']) 

$replyto (string) – E-mail address for replies



$name (string) – Display name for the reply-to e-mail address

CI_Email instance (method chaining) CI_Email to($to)  $to (mixed) – Comma-delimited string or an array of e-mail addresses 43

CodeIgniter

Return Return type

Syntax

CI_Email instance (method chaining) CI_Email

cc($cc) 

Parameters Return Return type

Syntax

$cc (mixed) – Comma-delimited string or an array of e-mail addresses

CI_Email instance (method chaining) CI_Email

bcc($bcc[, $limit = '']) 

$bcc (mixed) – Comma-delimited string or an array of e-mail addresses



$limit (int) – Maximum number of e-mails to send per batch

Parameters

Return Return type

Syntax Parameters Return Return type

Syntax Parameters Return Return type

Syntax Parameters Return Return type

Syntax Parameters Return Return type

CI_Email instance (method chaining) CI_Email

subject($subject) 

$subject (string) – E-mail subject line

CI_Email instance (method chaining) CI_Email

message($body)  $body (string) – E-mail message body CI_Email instance (method chaining) CI_Email

set_alt_message($str)  $str (string) – Alternative e-mail message body CI_Email instance (method chaining) CI_Email

set_header($header, $value)  $header (string) – Header name  $value (string) – Header value CI_Email instance (method chaining) CI_Email

44

CodeIgniter

Syntax Parameters Return Return type

Syntax Parameters Return Return type

Syntax

clear([$clear_attachments = FALSE]) 

$clear_attachments (bool) – Whether or not to clear attachments CI_Email instance (method chaining) CI_Email send([$auto_clear = TRUE]) 

$auto_clear (bool) – Whether to clear message data automatically CI_Email instance (method chaining) CI_Email attach($filename[, $disposition = ''[, $newname = NULL[, $mime = '']]]) 

$filename (string) – File name



$disposition (string) – ‘disposition’ of the attachment. Most email clients make their own decision regardless of the MIME specification used here. http://www.iana.org/assignments/contdisp/cont-disp.xhtml



$newname (string) – Custom file name to use in the e-mail



$mime (string) – MIME type to use (useful for buffered data)

Parameters

Return Return type

Syntax Parameters Return Return type

CI_Email instance (method chaining) CI_Email

attachment_cid($filename)  $filename (string) – Existing attachment filename Attachment Content-ID or FALSE if not found string

Sending an Email To send an email using CodeIgniter, first you have to load email library using the following:

$this->load->library('email'); After loading the library, simply execute the following functions to set necessary elements to send an email. The from() function is used to set- from where the email is being sent and to() function is used - to whom the email is being sent. The subject() and message() function is used to set the subject and message of the email.

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CodeIgniter

$this->email->from('[email protected]', 'Your Name'); $this->email->to('[email protected]'); $this->email->subject('Email Test'); $this->email->message('Testing the email class.'); After that, execute the send() function as shown below to send an email.

$this->email->send();

Example Create a controller file Email_controller.php application/controller/Email_controller.php.

and

save

it

in

Create a view file called application/views/email_form.php

email_form.php

and

save

it

at

CodeIgniter Email Example

47

CodeIgniter

Make the changes in the routes.php file in application/config/routes.php and add the following line at the end of the file. $route['email'] = 'Email_Controller'; Execute the above example by visiting the following link. Replace the yoursite.com with the URL of your site. http://yoursite.com/index.php/email

48

12. Form Validation

CodeIgniter

Validation is an important process while building web application. It ensures that the data that we are getting is proper and valid to store or process. CodeIgniter has made this task very easy. Let us understand this process with a simple example.

Example Create a view file myform.php and save the below code it in application/views/myform.php. This page will display form where user can submit his name and we will validate this page to ensure that it should not be empty while submitting. My Form





Name





Create a view file formsuccess.php and save it in application/views/formsuccess.php. This page will be displayed if the form is validated successfully. 49

CodeIgniter

My Form

Your form was successfully submitted!



Create a controller file Form.php and save it in application/controller/Form.php. This form will either, show errors if it is not validated properly or redirected to formsuccess.php page. Create a view file called session_view.php application/views/session_view.php

and

save

it

in

CodeIgniter Session Example Welcome Click Here to unset session data. Make the changes in the routes.php file in application/config/routes.php and add the following line at the end of the file. $route['sessionex'] = 'Session_Controller'; Execute the above example by using the following address. Replace yoursite.com with the URL of your site. http://yoursite.com/index.php/sessionex

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CodeIgniter

14. Flashdata

While building web application, we need to store some data for only one time and after that we want to remove that data. For example, to display some error message or information message. In PHP, we have to do it manually but CodeIgniter has made this job simple for us. In CodeIgniter, flashdata will only be available until the next request, and it will get deleted automatically.

Add Flashdata We can simply store flashdata as shown below. $this->session->mark_as_flash('item'); 

mark_as_flash() function is used for this purpose, which takes only one argument of the value to be stored. We can also pass an array to store multiple values.



set_flashdata() function can also be used, which takes two arguments, name and value, as shown below. We can also pass an array.

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

Retrieve Flashdata Flashdata can be retrieved using the flashdata() function which takes one argument of the item to be fetched as shown below. flashdata() function makes sure that you are getting only flash data and not any other data. $this->session->flashdata('item'); If you do not pass any argument, then you can get an array with the same function.

Example Create a class called FlashData_Controller.php application/controller/FlashData_Controller.php.

and

save

it

at

Create a view file called flashdata_home.php and save it in application/views/ flashdata_home.php CodeIgniter Flashdata Example Flash Data Example Click Here to add flash data.

Make the changes in the routes.php file in application/config/routes.php and add the following line at the end of the file. 59

CodeIgniter

$route['flashdata'] = 'FlashData_Controller'; $route['flashdata/add'] = 'FlashData_Controller/add'; Execute the above example by visiting the following link. Replace the yoursite.com with the URL of your site. http://yoursite.com/index.php/flashdata After visiting the above URL, you will see a screen as shown below.

Figure: Flashdata Example Click on “Click Here” link and you will see a screen as shown below. Here, in this screen you will see a value of flash data variable. Refresh the page again and you will see a screen like above and flash data variable will be removed automatically.

60

15. Tempdata

CodeIgniter

In some situations, where you want to remove data stored in session after some specific time-period, this can be done using tempdata functionality in CodeIgniter.

Add Tempdata To add data as tempdata, we have to use mark_as_tempdata() function. This function takes two argument items or items to be stored as tempdata and the expiration time for those items are as shown below. // 'item' will be erased after 300 seconds(5 minutes) $this->session->mark_as_temp('item',300); You can also pass an array to store multiple data. All the items stored below will be expired after 300 seconds. $this->session->mark_as_temp(array('item','item2'),300); You can also set different expiration time for each item as shown below. // 'item' will be erased after 300 seconds, while 'item2' // will do so after only 240 seconds $this->session->mark_as_temp(array( 'item'=>300, 'item2'=>240 ));

Retrieve Tempdata We can retrieve the tempdata using tempdata() function. This function assures that you are getting only tempdata and not any other data. Look at the example given below to see how to retrieve tempdata. tempdata() function will take one argument of the item to be fetched. $this->session->tempdata('item'); If you omit the argument, then you can retrieve all the existing tempdata.

Remove Tempdata Tempdata is removed automatically after its expiration time but if you want to remove tempdata before that, then you can do as shown below using the unset_tempdata() function, which takes one argument of the item to be removed. $this->session->unset_tempdata('item'); 61

CodeIgniter

Example Create a class called Tempdata_controller.php application/controller/Tempdata_controller.php.

and

save

it

in

Create a file called tempdata_view.php application/views/tempdata_view.php

and

save

it

in

CodeIgniter Tempdata Example Temp Data Example 62

CodeIgniter

Click Here to add temp data. Make the changes in the routes.php file in application/config/routes.php and add the following line at the end of the file. $route['tempdata'] = "Tempdata_controller"; $route['tempdata/add'] = "Tempdata_controller/add"; Execute the above example by visiting the following link. Replace the yoursite.com with the URL of your site. http://yoursite.com/index.php/tempdata After visiting the above URL, you will see a screen as shown below.

Click on “Click Here” link and you will see a screen as shown below. Here, in this screen you will see a value of temp data variable. Refresh the same page after five seconds again as we have set the temp data for five seconds and you will see a screen like above and temp data variable will be removed automatically after five seconds. If you refresh the same page before 5 seconds, then the temp data will not be removed, as the time period is not over.

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CodeIgniter

Destroying a Session In PHP, we are using the session_destroy() function to destroy the session and in CodeIgniter we can destroy the function as shown below. $this->session->sess_destroy(); After calling this function, all the session data including the flashdata and tempdata will be deleted permanently and cannot be retrieved back.

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CodeIgniter

16. Cookie Management

Cookie is a small piece of data sent from web server to store on client’s computer. CodeIgniter has one helper called “Cookie Helper” for cookie management. Syntax

set_cookie($name[, $value = ''[, $expire = ''[, $domain = ''[, $path = '/'[, $prefix = ''[, $secure = FALSE[, $httponly = FALSE]]]]]]]]) 

$name (mixed) – Cookie name or associative array of all of the parameters available to this function



$value (string) – Cookie value



$expire (int) – Number of seconds until expiration



$domain (string) .yourdomain.com)



$path (string) – Cookie path



$prefix (string) – Cookie name prefix



$secure (bool) – Whether to only send the cookie through HTTPS



$httponly (bool) – Whether to hide the cookie from JavaScript



Cookie

domain

(usually:

Parameters

Return type

void

In the set_cookie() function, we can pass all the values using two ways. In the first way, only array can be passed and in the second way, individual parameters can also be passed. Syntax

Parameters

Return Return type

get_cookie($index[, $xss_clean = NULL]]) 

$index (string) – Cookie name



$xss_clean (bool) – Whether to apply XSS filtering to the returned value

The cookie value or NULL if not found mixed

65

CodeIgniter

The get_cookie() function is used to get the cookie that has been set using the set_cookie() function. Syntax

delete_cookie($name[, $domain = ''[, $path = '/'[, $prefix = '']]]]) 

$name (string) – Cookie name



$domain (string) .yourdomain.com)



$path (string) – Cookie path



$prefix (string) – Cookie name prefix

Parameters

Return type



Cookie

domain

(usually:

void

The delete_cookie() function is used to delete the cookie().

Example Create a controller called Cookie_controller.php application/controller/Cookie_controller.php

and

save

it

at

Create a view file called Cookie_view.php application/views/Cookie_view.php

and

save

it

at

CodeIgniter View Example Click Here to view the cookie. Click Here to delete the cookie. Change the routes.php file in application/config/routes.php to add route for the above controller and add the following line at the end of the file. $route['cookie'] = "Cookie_controller"; $route['cookie/display'] = "Cookie_controller/display_cookie"; $route['cookie/delete'] = "Cookie_controller/deletecookie"; After that, you can execute the following URL in the browser to execute the example. http://yoursite.com/index.php/cookie It will produce an output as shown in the following screenshot.

67

17. Common Functions

CodeIgniter

CodeIgniter library functions and helper functions need to be initialized before they are used but there are some common functions, which do not need to be initialized. These common functions and their descriptions are given below. Syntax Parameters Return Return type Description

Syntax Parameters Return Return type Description

Syntax Parameters Return Return type Description

Syntax Parameters Return type Description

Syntax Parameters Return Return type Description

is_php($version)  $version (string) – Version number TRUE if the running PHP version is at least the one specified or FALSE if not void Determines if the PHP version being used is greater than the supplied version number.

is_really_writable($file)

 $file (string) – File path TRUE if the path is writable, FALSE if not bool checks to see if file is writable or not.

config_item($key)  $key (string) – Config item key Configuration key value or NULL if not found mixed This function is used to get the configuration item.

set_status_header($code[, $text = ''])  

$code (int) – HTTP Response status code $text (string) – A custom message to set with the status code

void This function permits you to manually set a server status header. remove_invisible_characters($str[, $url_encoded = TRUE])  $str (string) – Input string  $url_encoded (bool) – Whether to remove URLencoded characters as well Sanitized string string This function prevents inserting NULL characters between ASCII characters

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CodeIgniter

Syntax Parameters Return Return type Description

Syntax Return Return type Description

Syntax Return Return type Description

Syntax Return Return type Description

Syntax Parameters Return type Description

html_escape($var)  $var (mixed) – Variable to escape (string or array) HTML escaped string(s) mixed This function acts as a native PHP htmlspecialchars() function.

get_mimes() An associative array of file types array This function returns a reference to the MIMEs array from application/config/mimes.php.

is_https() TRUE if currently using HTTP-over-SSL, FALSE if not bool Returns TRUE if a secure (HTTPS) connection is used and FALSE in any other case (including non-HTTP requests).

is_cli() TRUE if currently running under CLI, FALSE otherwise bool Returns TRUE if the application is run through the command line and FALSE if not.

function_usable($function_name)  $function_name (string) – Function name bool Returns TRUE if a function exists and is usable, FALSE otherwise.

Given below is an example, which demonstrates all of the above functions.

Example Here we have created only one controller in which we will use the above functions. Copy the below given code and save it at application/controller/CommonFun_Controller.php. Change the routes.php file at application/config/routes.php to add route for the above controller and add the following line at the end of the file. $route['commonfunctions'] = 'CommonFun_Controller'; Type the following URL in the address bar of your browser to execute the example. http://yoursite.com/index.php/commonfunctions

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CodeIgniter

18. Page Caching

Caching a page will improve the page load speed. If the page is cached, then it will be stored in its fully rendered state. Next time, when the server gets a request for the cached page, it will be directly sent to the requested browser. Cached files are stored in application/cache folder. Caching can be enabled on per page basis. While enabling the cache, we need to set the time, until which it needs to remain in cached folder and after that period, it will be deleted automatically.

Enable Caching Caching can be enabled by executing the following line in any of the controller’s method. $this->output->cache($n); Where $n is the number of minutes, you wish the page to remain cached between refreshes.

Disable Caching Cache file gets deleted when it expires but when you want to delete it manually, then you have to disable it. You can disable the caching by executing the following line. // Deletes cache for the currently requested URI $this->output->delete_cache();

// Deletes cache for /foo/bar $this->output->delete_cache('/foo/bar');

Example Create a controller called Cache_controller.php application/controller/Cache_controller.php

and

save

it

in

Create a view file called test.php and save it in application/views/test.php CodeIgniter View Example CodeIgniter View Example Change the routes.php file in application/config/routes.php to add route for the above controller and add the following line at the end of the file. $route['cachecontroller'] = 'Cache_controller'; $route['cachecontroller/delete'] = 'Cache_controller/delete_file_cache'; Type the following URL in the browser to execute the example. http://yoursite.com/index.php/cachecontroller After visiting the above URL, you will see that a cache file for this will be created in application/cache folder. To delete the file, visit the following URL. http://yoursite.com/index.php/cachecontroller/delete

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CodeIgniter

19. Page Redirection

While building web application, we often need to redirect the user from one page to another page. CodeIgniter makes this job easy for us. The redirect() function is used for this purpose. Syntax

Parameters

Return type

redirect($uri = '', $method = 'auto', $code = NULL) 

$uri (string) – URI string



$method (string) – Redirect method (‘auto’, ‘location’ or ‘refresh’)



$code (string) – HTTP Response code (usually 302 or 303)

void

The first argument can have two types of URI. We can pass full site URL or URI segments to the controller you want to direct. The second optional parameter can have any of the three values from auto, location or refresh. The default is auto. The third optional parameter is only available with location redirects and it allows you to send specific HTTP response code.

Example Create a controller called Redirect_controller.php application/controller/Redirect_controller.php

and

save

it

in

Change the routes.php file in application/config/routes.php to add route for the above controller and add the following line at the end of the file. $route['redirect'] = 'Redirect_controller'; $route['redirect/version2'] = 'Redirect_controller/version2'; $route['redirect/computer_graphics'] = 'Redirect_controller/computer_graphics'; Type the following URL in the browser, to execute the example. http://yoursite.com/index.php/redirect The above URL will redirect you to the tutorialspoint.com website and if you visit the following URL, then it will redirect you to the computer graphics tutorial at tutorialspoint.com. http://yoursite.com/index.php/redirect/computer_graphics

74

20. Application Profiling

CodeIgniter

When building a web application, we are very much concerned about the performance of the website in terms of how much time the controller took to execute and how much memory is used. Not only the performance, but we also need to see the insights of data like POST data, data of database queries, session data etc. for debugging purpose while developing some application. CodeIgniter has made this job easier for us by profiling an application.

Enable Profiling To enable profiling of your application, simply execute the command given below in any of the method of your controller. $this->output->enable_profiler(TRUE); The report of the profiling can be seen at the bottom of the page after enabling it.

Disable Profiling To disable profiling of your application, simply execute the command given below in any of the method of your controller. $this->output->enable_profiler(FALSE);

Enable / Disable Profiler Section Profiling can be done on section basis. You can enable or disable profiling of a section by setting a Boolean value TRUE or FALSE. If you want to set profiling on the application then you can do in a file located in application/config/profiler.php For example, the following command will enable profiling queries for the whole application. $config['queries'] = TRUE; In the following table, the key is the parameter, which can be set in the config array to enable or disable a particular profile. Key

Description

Default TRUE

config

Elapsed time of Benchmark points and total execution time CodeIgniterConfig variables

controller_info

The Controller class and method requested

TRUE

get

Any GET data passed in the request

TRUE

http_headers

The HTTP headers for the current request

TRUE

benchmarks

TRUE

75

CodeIgniter

Amount of memory consumed by the current request, in bytes Any POST data passed in the request

TRUE

TRUE

uri_string

Listing of all database queries executed, including execution time The URI of the current request

session_data

Data stored in the current session

TRUE

query_toggle_count

The number of queries after which the query block will default to hidden.

memory_usage post queries

TRUE

TRUE

25

The profiler set in the file in application/config/profiler.php can be overridden by using the set_profiler_sections() function in controllers as shown below. $sections = array( 'config'

=> TRUE,

'queries' => TRUE );

$this->output->set_profiler_sections($sections);

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CodeIgniter

21. Benchmarking

Setting Benchmark Points If you want to measure the time taken to execute a set of lines or memory usage, you can calculate it by using Benchmarking points in CodeIgniter. There is a separate “Benchmarking” class for this purpose in CodeIgniter. This class is loaded automatically; you do not have to load it. It can be used anywhere in your controller, view, and model classes. All you have to do is to mark a start point and end point and then execute the elapsed_time() function between these two marked points and you can get the time it took to execute that code as shown below. To display the memory usage, use the function memory_usage() as shown in the following code.

Example Create a controller called Profiler_controller.php application/controller/Profiler_controller.php

and

save

it

in

Create a view file called test.php and save it at application/views/test.php CodeIgniter View Example CodeIgniter View Example Change the routes.php file at application/config/routes.php to add route for the above controller and add the following line at the end of the file. $route['profiler'] = "Profiler_controller"; $route['profiler/disable'] = "Profiler_controller/disable"; After that, you can type the following URL in the address bar of your browser to execute the example. http://yoursite.com/index.php/profiler

78

CodeIgniter

The above URL will enable the profiler and it will produce an output as shown in the following screenshot.

To disable the profiling, execute the following URL. http://yoursite.com/index.php/profiler/disable

79

22. Adding JS and CSS

CodeIgniter

Adding JavaScript and CSS (Cascading Style Sheet) file in CodeIgniter is very simple. You have to create JS and CSS folder in root directory and copy all the .js files in JS folder and .css files in CSS folder as shown in the figure.

For example, let us assume, you have created one JavaScript file sample.js and one CSS file style.css. Now, to add these files into your views, load URL helper in your controller as shown below. $this->load->helper('url'); After loading the URL helper in controller, simply add the below given lines in the view file, to load the sample.js and style.css file in the view as shown below. Create a view file called test.php and save it at application/views/test.php CodeIgniter View Example css/style.css">

type="text/css"

js/sample.js">

href="
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