user_guide_src/source/libraries/output.rst

############
Output Class
############

The Output class is a core class with one main function: To send the
finalized web page to the requesting browser. It is also responsible for
:doc:`caching <../general/caching>` your web pages, if you use that
feature.

.. note:: This class is initialized automatically by the system so there
	is no need to do it manually.

Under normal circumstances you won't even notice the Output class since
it works transparently without your intervention. For example, when you
use the :doc:`Loader <../libraries/loader>` class to load a view file,
it's automatically passed to the Output class, which will be called
automatically by CodeIgniter at the end of system execution. It is
possible, however, for you to manually intervene with the output if you
need to.

.. contents::
  :local:

.. raw:: html

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

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

.. php:class:: CI_Output

	.. attribute:: $parse_exec_vars = TRUE;

		Enables/disables parsing of the {elapsed_time} and {memory_usage} pseudo-variables.

		CodeIgniter will parse those tokens in your output by default. To disable this, set
		this property to FALSE in your controller.
		::

			$this->output->parse_exec_vars = FALSE;

	.. php:method:: set_output($output)

		:param	string	$output: String to set the output to
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Permits you to manually set the final output string. Usage example::

			$this->output->set_output($data);

		.. important:: If you do set your output manually, it must be the last thing done
			in the function you call it from. For example, if you build a page in one
			of your controller methods, don't set the output until the end.

	.. php:method:: set_content_type($mime_type[, $charset = NULL])

		:param	string	$mime_type: MIME Type idenitifer string
		:param	string	$charset: Character set
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Permits you to set the mime-type of your page so you can serve JSON data, JPEG's, XML, etc easily.
		::

			$this->output
				->set_content_type('application/json')
				->set_output(json_encode(array('foo' => 'bar')));

			$this->output
				->set_content_type('jpeg') // You could also use ".jpeg" which will have the full stop removed before looking in config/mimes.php
				->set_output(file_get_contents('files/something.jpg'));

		.. important:: Make sure any non-mime string you pass to this method
			exists in *application/config/mimes.php* or it will have no effect.

		You can also set the character set of the document, by passing a second argument::

			$this->output->set_content_type('css', 'utf-8');

	.. php:method:: get_content_type()

		:returns:	Content-Type string
		:rtype:	string

		Returns the Content-Type HTTP header that's currently in use, excluding the character set value.
		::

			$mime = $this->output->get_content_type();

		.. note:: If not set, the default return value is 'text/html'.

	.. php:method:: get_header($header)

		:param	string	$header: HTTP header name
		:returns:	HTTP response header or NULL if not found
		:rtype:	mixed

		Returns the requested HTTP header value, or NULL if the requested header is not set.
		Example::

			$this->output->set_content_type('text/plain', 'UTF-8');
			echo $this->output->get_header('content-type');
			// Outputs: text/plain; charset=utf-8

		.. note:: The header name is compared in a case-insensitive manner.

		.. note:: Raw headers sent via PHP's native ``header()`` function are also detected.

	.. php:method:: get_output()

		:returns:	Output string
		:rtype:	string

		Permits you to manually retrieve any output that has been sent for
		storage in the output class. Usage example::

			$string = $this->output->get_output();

		Note that data will only be retrievable from this function if it has
		been previously sent to the output class by one of the CodeIgniter
		functions like ``$this->load->view()``.

	.. php:method:: append_output($output)

		:param	string	$output: Additional output data to append
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Appends data onto the output string.
		::

			$this->output->append_output($data);

	.. php:method:: set_header($header[, $replace = TRUE])

		:param	string	$header: HTTP response header
		:param	bool	$replace: Whether to replace the old header value, if it is already set
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Permits you to manually set server headers, which the output class will
		send for you when outputting the final rendered display. Example::

			$this->output->set_header('HTTP/1.0 200 OK');
			$this->output->set_header('HTTP/1.1 200 OK');
			$this->output->set_header('Last-Modified: '.gmdate('D, d M Y H:i:s', $last_update).' GMT');
			$this->output->set_header('Cache-Control: no-store, no-cache, must-revalidate');
			$this->output->set_header('Cache-Control: post-check=0, pre-check=0');
			$this->output->set_header('Pragma: no-cache');

	.. php:method:: set_status_header([$code = 200[, $text = '']])

		:param	int	$code: HTTP status code
		:param	string	$text: Optional message
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Permits you to manually set a server status header. Example::

			$this->output->set_status_header('401');
			// Sets the header as:  Unauthorized

		`See here <http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html>`_ for a full list of headers.

		.. note:: This method is an alias for :doc:`Common function <../general/common_functions>`
			:func:`set_status_header()`.

	.. php:method:: enable_profiler([$val = TRUE])

		:param	bool	$val: Whether to enable or disable the Profiler
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Permits you to enable/disable the :doc:`Profiler <../general/profiling>`, which will display benchmark
		and other data at the bottom of your pages for debugging and optimization purposes.

		To enable the profiler place the following line anywhere within your
		:doc:`Controller <../general/controllers>` methods::

			$this->output->enable_profiler(TRUE);

		When enabled a report will be generated and inserted at the bottom of your pages.

		To disable the profiler you would use::

			$this->output->enable_profiler(FALSE);

	.. php:method:: set_profiler_sections($sections)

		:param	array	$sections: Profiler sections
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Permits you to enable/disable specific sections of the Profiler when it is enabled.
		Please refer to the :doc:`Profiler <../general/profiling>` documentation for further information.

	.. php:method:: cache($time)

		:param	int	$time: Cache expiration time in seconds
		:returns:	CI_Output instance (method chaining)
		:rtype:	CI_Output

		Caches the current page for the specified amount of seconds.

		For more information, please see the :doc:`caching documentation <../general/caching>`.

	.. php:method:: _display([$output = ''])

		:param	string	$output: Output data override
		:returns:	void
		:rtype:	void

		Sends finalized output data to the browser along with any server headers. It also stops benchmark
		timers.

		.. note:: This method is called automatically at the end of script execution, you won't need to 
			call it manually unless you are aborting script execution using ``exit()`` or ``die()`` in your code.
		
		Example::

			$response = array('status' => 'OK');

			$this->output
				->set_status_header(200)
				->set_content_type('application/json', 'utf-8')
				->set_output(json_encode($response, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES))
				->_display();
			exit;

		.. note:: Calling this method manually without aborting script execution will result in duplicated output.