user_guide_src/source/libraries/trackback.rst - code-igniter-v3-giggi - Gitiles

 ###############
 Trackback Class
 ###############

 The Trackback Class provides functions that enable you to send and
 receive Trackback data.

 If you are not familiar with Trackbacks you'll find more information
 `here <http://en.wikipedia.org/wiki/Trackback>`_.

 .. contents::
   :local:

 .. raw:: html

   <div class="custom-index container"></div>

 *************************
 Using the Trackback Class
 *************************

 Initializing the Class
 ======================

 Like most other classes in CodeIgniter, the Trackback class is
 initialized in your controller using the ``$this->load->library()`` method::

 	$this->load->library('trackback');

 Once loaded, the Trackback library object will be available using::

 	$this->trackback

 Sending Trackbacks
 ==================

 A Trackback can be sent from any of your controller functions using code
 similar to this example::

 	$this->load->library('trackback');

 	$tb_data = array(
 		'ping_url'  => 'http://example.com/trackback/456',
 		'url'       => 'http://www.my-example.com/blog/entry/123',
 		'title'     => 'The Title of My Entry',
 		'excerpt'   => 'The entry content.',
 		'blog_name' => 'My Blog Name',
 		'charset'   => 'utf-8'
 	);

 	if ( ! $this->trackback->send($tb_data))
 	{
 		echo $this->trackback->display_errors();
 	}
 	else
 	{
 		echo 'Trackback was sent!';
 	}

 Description of array data:

 -  **ping_url** - The URL of the site you are sending the Trackback to.
    You can send Trackbacks to multiple URLs by separating each URL with a comma.
 -  **url** - The URL to YOUR site where the weblog entry can be seen.
 -  **title** - The title of your weblog entry.
 -  **excerpt** - The content of your weblog entry.
 -  **blog_name** - The name of your weblog.
 -  **charset** - The character encoding your weblog is written in. If omitted, UTF-8 will be used.

 .. note:: The Trackback class will automatically send only the first 500 characters of your
 	entry. It will also strip all HTML.

 The Trackback sending method returns TRUE/FALSE (boolean) on success
 or failure. If it fails, you can retrieve the error message using::

 	$this->trackback->display_errors();

 Receiving Trackbacks
 ====================

 Before you can receive Trackbacks you must create a weblog. If you don't
 have a blog yet there's no point in continuing.

 Receiving Trackbacks is a little more complex than sending them, only
 because you will need a database table in which to store them, and you
 will need to validate the incoming trackback data. You are encouraged to
 implement a thorough validation process to guard against spam and
 duplicate data. You may also want to limit the number of Trackbacks you
 allow from a particular IP within a given span of time to further
 curtail spam. The process of receiving a Trackback is quite simple; the
 validation is what takes most of the effort.

 Your Ping URL
 =============

 In order to accept Trackbacks you must display a Trackback URL next to
 each one of your weblog entries. This will be the URL that people will
 use to send you Trackbacks (we will refer to this as your "Ping URL").

 Your Ping URL must point to a controller function where your Trackback
 receiving code is located, and the URL must contain the ID number for
 each particular entry, so that when the Trackback is received you'll be
 able to associate it with a particular entry.

 For example, if your controller class is called Trackback, and the
 receiving function is called receive, your Ping URLs will look something
 like this::

 	http://example.com/index.php/trackback/receive/entry_id

 Where entry_id represents the individual ID number for each of your
 entries.

 Creating a Trackback Table
 ==========================

 Before you can receive Trackbacks you must create a table in which to
 store them. Here is a basic prototype for such a table::

 	CREATE TABLE trackbacks (
 		tb_id int(10) unsigned NOT NULL auto_increment,
 		entry_id int(10) unsigned NOT NULL default 0,
 		url varchar(200) NOT NULL,
 		title varchar(100) NOT NULL,
 		excerpt text NOT NULL,
 		blog_name varchar(100) NOT NULL,
 		tb_date int(10) NOT NULL,
 		ip_address varchar(45) NOT NULL,
 		PRIMARY KEY `tb_id` (`tb_id`),
 		KEY `entry_id` (`entry_id`)
 	);

 The Trackback specification only requires four pieces of information to
 be sent in a Trackback (url, title, excerpt, blog_name), but to make
 the data more useful we've added a few more fields in the above table
 schema (date, IP address, etc.).

 Processing a Trackback
 ======================

 Here is an example showing how you will receive and process a Trackback.
 The following code is intended for use within the controller function
 where you expect to receive Trackbacks.::

 	$this->load->library('trackback');
 	$this->load->database();

 	if ($this->uri->segment(3) == FALSE)
 	{
 		$this->trackback->send_error('Unable to determine the entry ID');
 	}

 	if ( ! $this->trackback->receive())
 	{
 		$this->trackback->send_error('The Trackback did not contain valid data');
 	}

 	$data = array(
 		'tb_id'      => '',
 		'entry_id'   => $this->uri->segment(3),
 		'url'        => $this->trackback->data('url'),
 		'title'      => $this->trackback->data('title'),
 		'excerpt'    => $this->trackback->data('excerpt'),
 		'blog_name'  => $this->trackback->data('blog_name'),
 		'tb_date'    => time(),
 		'ip_address' => $this->input->ip_address()
 	);

 	$sql = $this->db->insert_string('trackbacks', $data);
 	$this->db->query($sql);

 	$this->trackback->send_success();

 Notes:
 ^^^^^^

 The entry ID number is expected in the third segment of your URL. This
 is based on the URI example we gave earlier::

 	http://example.com/index.php/trackback/receive/entry_id

 Notice the entry_id is in the third URI segment, which you can retrieve
 using::

 	$this->uri->segment(3);

 In our Trackback receiving code above, if the third segment is missing,
 we will issue an error. Without a valid entry ID, there's no reason to
 continue.

 The $this->trackback->receive() function is simply a validation function
 that looks at the incoming data and makes sure it contains the four
 pieces of data that are required (url, title, excerpt, blog_name). It
 returns TRUE on success and FALSE on failure. If it fails you will issue
 an error message.

 The incoming Trackback data can be retrieved using this function::

 	$this->trackback->data('item')

 Where item represents one of these four pieces of info: url, title,
 excerpt, or blog_name

 If the Trackback data is successfully received, you will issue a success
 message using::

 	$this->trackback->send_success();

 .. note:: The above code contains no data validation, which you are
 	encouraged to add.

 ***************
 Class Reference
 ***************

 .. php:class:: CI_Trackback

 	.. attribute:: $data = array('url' => '', 'title' => '', 'excerpt' => '', 'blog_name' => '', 'charset' => '')

 		Trackback data array.

 	.. attribute:: $convert_ascii = TRUE

 		Whether to convert high ASCII and MS Word characters to HTML entities.

 	.. php:method:: send($tb_data)

 		:param	array	$tb_data: Trackback data
 		:returns:	TRUE on success, FALSE on failure
 		:rtype:	bool

 		Send trackback.

 	.. php:method:: receive()

 		:returns:	TRUE on success, FALSE on failure
 		:rtype:	bool

 		This method simply validates the incoming TB data, returning TRUE on success and FALSE on failure.
 		If the data is valid it is set to the ``$this->data`` array so that it can be inserted into a database.

 	.. php:method:: send_error([$message = 'Incomplete information')

 		:param	string	$message: Error message
 		:rtype: void

 		Responses to a trackback request with an error message.

 		.. note:: This method will terminate script execution.

 	.. php:method:: send_success()

 		:rtype:	void

 		Responses to a trackback request with a success message.

 		.. note:: This method will terminate script execution.

 	.. php:method:: data($item)

 		:param	string	$item: Data key
 		:returns:	Data value or empty string if not found
 		:rtype:	string

 		Returns a single item from the reponse data array.

 	.. php:method:: process($url, $data)

 		:param	string	$url: Target url
 		:param	string	$data: Raw POST data
 		:returns:	TRUE on success, FALSE on failure
 		:rtype:	bool

 		Opens a socket connection and passes the data to the server, returning TRUE on success and FALSE on failure.

 	.. php:method:: extract_urls($urls)

 		:param	string	$urls: Comma-separated URL list
 		:returns:	Array of URLs
 		:rtype:	array

 		This method lets multiple trackbacks to be sent. It takes a string of URLs (separated by comma or space) and puts each URL into an array.

 	.. php:method:: validate_url(&$url)

 		:param	string	$url: Trackback URL
 		:rtype:	void

 		Simply adds the *http://* prefix it it's not already present in the URL.

 	.. php:method:: get_id($url)

 		:param	string	$url: Trackback URL
 		:returns:	URL ID or FALSE on failure
 		:rtype:	string

 		Find and return a trackback URL's ID or FALSE on failure.

 	.. php:method:: convert_xml($str)

 		:param	string	$str: Input string
 		:returns:	Converted string
 		:rtype:	string

 		Converts reserved XML characters to entities.

 	.. php:method:: limit_characters($str[, $n = 500[, $end_char = '&#8230;']])

 		:param	string	$str: Input string
 		:param	int	$n: Max characters number
 		:param	string	$end_char: Character to put at end of string
 		:returns:	Shortened string
 		:rtype:	string

 		Limits the string based on the character count. Will preserve complete words.

 	.. php:method:: convert_ascii($str)

 		:param	string	$str: Input string
 		:returns:	Converted string
 		:rtype:	string

 		Converts high ASCII text and MS Word special characterss to HTML entities.

 	.. php:method:: set_error($msg)

 		:param	string	$msg: Error message
 		:rtype:	void

 		Set an log an error message.

 	.. php:method:: display_errors([$open = '<p>'[, $close = '</p>']])

 		:param	string	$open: Open tag
 		:param	string	$close: Close tag
 		:returns:	HTML formatted error messages
 		:rtype:	string

 		Returns error messages formatted in HTML or an empty string if there are no errors.
	###############
	Trackback Class
	###############

	The Trackback Class provides functions that enable you to send and
	receive Trackback data.

	If you are not familiar with Trackbacks you'll find more information
	`here <http://en.wikipedia.org/wiki/Trackback>`_.

	.. contents::
	:local:

	.. raw:: html

	<div class="custom-index container"></div>

	*************************
	Using the Trackback Class
	*************************

	Initializing the Class
	======================

	Like most other classes in CodeIgniter, the Trackback class is
	initialized in your controller using the ``$this->load->library()`` method::

	$this->load->library('trackback');

	Once loaded, the Trackback library object will be available using::

	$this->trackback

	Sending Trackbacks
	==================

	A Trackback can be sent from any of your controller functions using code
	similar to this example::

	$this->load->library('trackback');

	$tb_data = array(
	'ping_url' => 'http://example.com/trackback/456',
	'url' => 'http://www.my-example.com/blog/entry/123',
	'title' => 'The Title of My Entry',
	'excerpt' => 'The entry content.',
	'blog_name' => 'My Blog Name',
	'charset' => 'utf-8'
	);

	if ( ! $this->trackback->send($tb_data))
	{
	echo $this->trackback->display_errors();
	}
	else
	{
	echo 'Trackback was sent!';
	}

	Description of array data:

	- ping_url - The URL of the site you are sending the Trackback to.
	You can send Trackbacks to multiple URLs by separating each URL with a comma.
	- url - The URL to YOUR site where the weblog entry can be seen.
	- title - The title of your weblog entry.
	- excerpt - The content of your weblog entry.
	- blog_name - The name of your weblog.
	- charset - The character encoding your weblog is written in. If omitted, UTF-8 will be used.

	.. note:: The Trackback class will automatically send only the first 500 characters of your
	entry. It will also strip all HTML.

	The Trackback sending method returns TRUE/FALSE (boolean) on success
	or failure. If it fails, you can retrieve the error message using::

	$this->trackback->display_errors();

	Receiving Trackbacks
	====================

	Before you can receive Trackbacks you must create a weblog. If you don't
	have a blog yet there's no point in continuing.

	Receiving Trackbacks is a little more complex than sending them, only
	because you will need a database table in which to store them, and you
	will need to validate the incoming trackback data. You are encouraged to
	implement a thorough validation process to guard against spam and
	duplicate data. You may also want to limit the number of Trackbacks you
	allow from a particular IP within a given span of time to further
	curtail spam. The process of receiving a Trackback is quite simple; the
	validation is what takes most of the effort.

	Your Ping URL
	=============

	In order to accept Trackbacks you must display a Trackback URL next to
	each one of your weblog entries. This will be the URL that people will
	use to send you Trackbacks (we will refer to this as your "Ping URL").

	Your Ping URL must point to a controller function where your Trackback
	receiving code is located, and the URL must contain the ID number for
	each particular entry, so that when the Trackback is received you'll be
	able to associate it with a particular entry.

	For example, if your controller class is called Trackback, and the
	receiving function is called receive, your Ping URLs will look something
	like this::

	http://example.com/index.php/trackback/receive/entry_id

	Where entry_id represents the individual ID number for each of your
	entries.

	Creating a Trackback Table
	==========================

	Before you can receive Trackbacks you must create a table in which to
	store them. Here is a basic prototype for such a table::

	CREATE TABLE trackbacks (
	tb_id int(10) unsigned NOT NULL auto_increment,
	entry_id int(10) unsigned NOT NULL default 0,
	url varchar(200) NOT NULL,
	title varchar(100) NOT NULL,
	excerpt text NOT NULL,
	blog_name varchar(100) NOT NULL,
	tb_date int(10) NOT NULL,
	ip_address varchar(45) NOT NULL,
	PRIMARY KEY `tb_id` (`tb_id`),
	KEY `entry_id` (`entry_id`)
	);

	The Trackback specification only requires four pieces of information to
	be sent in a Trackback (url, title, excerpt, blog_name), but to make
	the data more useful we've added a few more fields in the above table
	schema (date, IP address, etc.).

	Processing a Trackback
	======================

	Here is an example showing how you will receive and process a Trackback.
	The following code is intended for use within the controller function
	where you expect to receive Trackbacks.::

	$this->load->library('trackback');
	$this->load->database();

	if ($this->uri->segment(3) == FALSE)
	{
	$this->trackback->send_error('Unable to determine the entry ID');
	}

	if ( ! $this->trackback->receive())
	{
	$this->trackback->send_error('The Trackback did not contain valid data');
	}

	$data = array(
	'tb_id' => '',
	'entry_id' => $this->uri->segment(3),
	'url' => $this->trackback->data('url'),
	'title' => $this->trackback->data('title'),
	'excerpt' => $this->trackback->data('excerpt'),
	'blog_name' => $this->trackback->data('blog_name'),
	'tb_date' => time(),
	'ip_address' => $this->input->ip_address()
	);

	$sql = $this->db->insert_string('trackbacks', $data);
	$this->db->query($sql);

	$this->trackback->send_success();

	Notes:
	^^^^^^

	The entry ID number is expected in the third segment of your URL. This
	is based on the URI example we gave earlier::

	http://example.com/index.php/trackback/receive/entry_id

	Notice the entry_id is in the third URI segment, which you can retrieve
	using::

	$this->uri->segment(3);

	In our Trackback receiving code above, if the third segment is missing,
	we will issue an error. Without a valid entry ID, there's no reason to
	continue.

	The $this->trackback->receive() function is simply a validation function
	that looks at the incoming data and makes sure it contains the four
	pieces of data that are required (url, title, excerpt, blog_name). It
	returns TRUE on success and FALSE on failure. If it fails you will issue
	an error message.

	The incoming Trackback data can be retrieved using this function::

	$this->trackback->data('item')

	Where item represents one of these four pieces of info: url, title,
	excerpt, or blog_name

	If the Trackback data is successfully received, you will issue a success
	message using::

	$this->trackback->send_success();

	.. note:: The above code contains no data validation, which you are
	encouraged to add.

	***************
	Class Reference
	***************

	.. php:class:: CI_Trackback

	.. attribute:: $data = array('url' => '', 'title' => '', 'excerpt' => '', 'blog_name' => '', 'charset' => '')

	Trackback data array.

	.. attribute:: $convert_ascii = TRUE

	Whether to convert high ASCII and MS Word characters to HTML entities.

	.. php:method:: send($tb_data)

	:param array $tb_data: Trackback data
	:returns: TRUE on success, FALSE on failure
	:rtype: bool

	Send trackback.

	.. php:method:: receive()

	:returns: TRUE on success, FALSE on failure
	:rtype: bool

	This method simply validates the incoming TB data, returning TRUE on success and FALSE on failure.
	If the data is valid it is set to the ``$this->data`` array so that it can be inserted into a database.

	.. php:method:: send_error([$message = 'Incomplete information')

	:param string $message: Error message
	:rtype: void

	Responses to a trackback request with an error message.

	.. note:: This method will terminate script execution.

	.. php:method:: send_success()

	:rtype: void

	Responses to a trackback request with a success message.

	.. note:: This method will terminate script execution.

	.. php:method:: data($item)

	:param string $item: Data key
	:returns: Data value or empty string if not found
	:rtype: string

	Returns a single item from the reponse data array.

	.. php:method:: process($url, $data)

	:param string $url: Target url
	:param string $data: Raw POST data
	:returns: TRUE on success, FALSE on failure
	:rtype: bool

	Opens a socket connection and passes the data to the server, returning TRUE on success and FALSE on failure.

	.. php:method:: extract_urls($urls)

	:param string $urls: Comma-separated URL list
	:returns: Array of URLs
	:rtype: array

	This method lets multiple trackbacks to be sent. It takes a string of URLs (separated by comma or space) and puts each URL into an array.

	.. php:method:: validate_url(&$url)

	:param string $url: Trackback URL
	:rtype: void

	Simply adds the http:// prefix it it's not already present in the URL.

	.. php:method:: get_id($url)

	:param string $url: Trackback URL
	:returns: URL ID or FALSE on failure
	:rtype: string

	Find and return a trackback URL's ID or FALSE on failure.

	.. php:method:: convert_xml($str)

	:param string $str: Input string
	:returns: Converted string
	:rtype: string

	Converts reserved XML characters to entities.

	.. php:method:: limit_characters($str[, $n = 500[, $end_char = '…']])

	:param string $str: Input string
	:param int $n: Max characters number
	:param string $end_char: Character to put at end of string
	:returns: Shortened string
	:rtype: string

	Limits the string based on the character count. Will preserve complete words.

	.. php:method:: convert_ascii($str)

	:param string $str: Input string
	:returns: Converted string
	:rtype: string

	Converts high ASCII text and MS Word special characterss to HTML entities.

	.. php:method:: set_error($msg)

	:param string $msg: Error message
	:rtype: void

	Set an log an error message.

	.. php:method:: display_errors([$open = '<p>'[, $close = '</p>']])

	:param string $open: Open tag
	:param string $close: Close tag
	:returns: HTML formatted error messages
	:rtype: string

	Returns error messages formatted in HTML or an empty string if there are no errors.