My base admin controller for my custom cms.

Admin_Controller.php

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

/**
* Admin Controller
*
* Provides methods and properties for all admin related objects.
*
*/
class Admin_Controller extends CI_Controller{
	
	//--------------------------------------------------------------------------	
	
	/**
	 *  An array of resources we want to exclude from authentication.
	 *  This is needed for the login and other lower level modules.
	 *  These are all defined in the app config file in the app_exclude_resources array.
	 * 
	 * @var array
	 */
	
	protected $exclude;
	
	//--------------------------------------------------------------------------	
	
	/**
	* Initialize the modules array.
	* 
	* @var array
	*/
	protected $modules = array();

	//--------------------------------------------------------------------------

	/**
	 * The name of the current model table we will be working with.
	 * 
	 * @var string
	 */
	protected $db_table;

	//--------------------------------------------------------------------------

	/**
	 * An array of models required by the current model.
	 * The prototype should follow	
	 * $this->db_requires = array('module_type'=>array('model_name','model_name2'));
	 * The module type is the same name as the folder where the models reside.
	 * 
	 * $this->db_requires = array('module_name'=>array('model_name','model_name2'));
	 * @var array
	 */
	protected $db_requires;

	//--------------------------------------------------------------------------
	
	/**
	* The fields property holds an array of table column names.
	* This is defined by each model and is initialized in the 
	* CI_Model class.
	* 
	* @var array
	*/
	protected $db_fields;
	
	//--------------------------------------------------------------------------

	/**
	 * The module segment in our uri: http://site.com/module/class/method/id
	 * 
	 * @var string
	 */
	protected $module;
	
	//--------------------------------------------------------------------------
	
	/**
	 * The name of admin class in our uri: http://site.com/module/class/method/id
	 *  @var string
	 */
	protected $admin;

	//--------------------------------------------------------------------------

	/**
	 * The method segment in our uri: http://site.com/module/class/method/id
	 * 
	 * @var string
	 */
	protected $method;

	//--------------------------------------------------------------------------

	/**
	 * The id segment in our uri: http://site.com/module/class/method/id
	 * 
	 * @var string 
	 */
	protected $id;
	
	//--------------------------------------------------------------------------
	
	/**
	* Constructor
	*
	* Creates our admin controller object
	*
	* @return object Admin_Controller
	*/
	public function __construct()
	{
		//Call the parent constructor
		parent::__construct();
		
		//Run this code before anyting else runs.	
		$this->_before();
		
		//Check if this user has access to the resource being requested.
		$this->_authenticate($this->module, $this->admin, $this->method, $this->exclude);
		
		//Load Models
		$this->_load_models();
		
		//Set the page level variables.
		$this->_set_vars();

        //Run the system usage tracker
		$this->_track_usage();
		
		//Once our bootstrapping and checking is done run this code.
		$this->_after();
	}
	
	//--------------------------------------------------------------------------
	
	private function _before()
	{
		write_log('Running before function.');
	
		//If the enable profiler is on let's print the results
		if (app('app_enable_profiler') == TRUE)
		{
			$this->output->enable_profiler(TRUE);
		}
		
		$this->exclude	= app('app_exclude_resources');
		$this->module 	= (segment(1)) ? segment(1) : 'dashboard';
		$this->admin 	= 'admin';
		$this->method 	= (segment(3)) ? segment(3) : 'index';
		$this->id 		= (segment(4)) ? segment(4) : '';
		
		// if(is_post())
		// 		{
		// 			write_log($this->method .'_post');
		// 			$this->_load_models();
		// 			$m = $this->method .'_post';
		// 			$this->$m();
		// 		}
	}
	
	//--------------------------------------------------------------------------
	
	private function _after()
	{
		write_log('Running after function.');
	}
	
	//--------------------------------------------------------------------------
	
	/**
	 * Authenticate
	 * 
	 * Checks to see of the current user has has access to the current resources.
	 * 
	 * @param string $module The name of the module we are checking for. 
	 * @param string $admin The name of the admin controller.
	 * @param string $method The name of the method in the admin controller we are checking for.
	 * @param array $exclude_resources An array of resources to exclude from authentication. 
	 * Used for the login and other controllers that would cause an infinite loop since we are 
	 * extending the admin_controller.
	 * @return mixed If a user has access return true if not redirect to the denied message.
	 */
	private function _authenticate($module, $admin, $method, $exclude)
	{
		$group_id = $this->session->userdata('group_id');
		$resource = $this->module .'/'. $this->admin .'/'. $this->method;
		
		//If the user is not logged in let's redirect them.
		if ($group_id == '')
		{
			if ( ! in_array($resource, $exclude))
			{
				redirect('login/admin');
			}
		}
		
		if( ! in_array($resource, $exclude))
		{
			if ($this->permission_model->is_allowed($group_id, $resource) === TRUE)
			{
				return TRUE;
			}
			else
			{
				if (segment(1) == 'admin')
				{
					redirect(app('app_default_admin_controller') . '/' . app('app_default_admin_method'));
				}
				else
				{
					redirect('denied/admin/index/'. $this->module .'/'. $this->admin .'/'. $this->method);
				}
				
			}
		}
	}
	
	//--------------------------------------------------------------------------
	
	private function _load_models()
	{
		
		//Load a model for this controller if available		
		$model_name = $this->module .'_model';
	
		if (file_exists(APPPATH . 'modules/'. $this->module .'/models/'. $model_name .'.php' ))
		{
			$this->load->model($this->module .'/'. $model_name);
			$this->db_fields			= $this->$model_name->db_fields;
			$this->db_table 			= $this->$model_name->db_table;
			$this->db_requires 			= $this->$model_name->db_requires;
			$this->$model_name->module 	= $this->module;
			$this->$model_name->method 	= $this->method;
			$this->$model_name->id 		= $this->id;
		}
		
		//If the db_requires array is not empty let's load the models declared in the array.
		if (count($this->db_requires) != 0)
		{
			foreach($this->db_requires as $module=>$model_names)
			{
				foreach($model_names as $model_name)
				{
					if (file_exists(APPPATH . 'modules/'. $module .'/models/'. $model_name .'.php'))
					{
						$this->load->model($module .'/'. $model_name);
					}
				}
			}
		}
	}
	
	//--------------------------------------------------------------------------
	
	private function _set_vars()
	{
		//Define our template for all tables in the admin section
		$this->table->set_template(app('app_table_template'));

		//Gray bar title above the content in the right column of the template.
		if ($this->method == 'index')
		{
			$data['action_title'] = readable($this->module) .' Home';
		}
		else
		{
			$data['action_title'] = readable($this->method) .' '. readable($this->module); 
		}
	
		//Set the default module title so we can use it in our template.
		$data['module_title'] = readable($this->module);
	
		//Set the default form action based on the current action
		$data['form_action'] = $this->uri->uri_string();
	
		//Set the default submit button title based on the method.
		$data['submit'] = ($this->method == 'create') ? 'Add' : 'Save';
		
		//Set the breadcrumb string to empty
		$data['breadcrumb_string'] = NULL;

		//Let's load all these data variables into the global scope.
		$this->load->vars($data);
	}
	
	//--------------------------------------------------------------------------
	
	private function _track_usage()
	{
		if (app('app_enable_log') == TRUE)
		{
			$log_data['user_id'] 			= $this->session->userdata('user_id');
			$log_data['resource'] 			= $this->uri->uri_string();
			$log_data['action_timestamp'] 	= date('Y:m:d h:i:s');
			$log_data['message_type']		= 'log';
			$log_data['message'] 			= 'Automatic tracking of activity in application.';
			$log_data['ip'] 				= $_SERVER['REMOTE_ADDR'];
			$this->log_model->save($log_data);
		}
	}
	
	//--------------------------------------------------------------------------
	
	/**
	* Renders a view using our convention-based approach
    * Get the current uri from the uri_string ci method and explode into
    * an array so we can manipulate the various parts.
    *
    * @param array $data An array of data items for our view. $view_data['item'] = value
    * @return object $view Returns a view with our content   
	*/
	public function render($data = array(), $template = NULL, $view = NULL)
	{
        $theme 	= app('app_system_theme');
		$module = $this->module;
		$admin = $this->admin;
        $method	= $this->method;
		$id = $this->id;
		
		//The name of main admin template to load. 
        if ($template == NULL)
        {
            $template = 'template';
        }
        
        //If the data array is not empty lets loop thru it and create our variables for our view
        if (count($data) > 0)
        {
            foreach($data as $item=>$value)
            {
                $view_data[$item] = $value;
            }
        }
        else
        {
        	$view_data[] = '';
        }
		
		//The name of the view file, the sub template
		if ($view == NULL)
        {
        	$view = $this->load->view($method, $view_data , TRUE);
        }
        else
        {
        	$view = $this->load->view($view, $view_data, TRUE);
        }

		$data['page_id'] 	= $module;
        $data['page_class']	= $method;
        $data['content'] 	= $view;
		//echo 'themes/admin/'. $theme . $template;
        $this->load->external_view('themes/admin/'. $theme .'/', $template, $data);
	}
	
	//--------------------------------------------------------------------------

	/**
	 * Handles the batch actions for all our table views.
	 *
	 * @param string $action 
	 * @return void
	 * @author Alex Garcia
	 */
	public function batch($action = NULL)
	{
		$batch_action = $this->input->post('batch_action');
		$model = $this->module .'_model';
		$this->load->model($this->module .'/'. $model);
		$model = $this->module .'_model';
		switch($batch_action)
		{
			case 'batch_delete':
				foreach($_POST as $key=>$value)
				{
					if($key != 'batch_action')
					{
						if($key != 'batch_submit')
						{
							if($value == 1)
							{
								if ($this->input->post('src') == 'module_resources')
								{ 
									$this->load->model('module_resource/module_resource_model');
									$this->module_resource_model->delete($key);
									$module_id = $this->input->post('module_id');
									$redirect = $this->module .'/'. $this->admin .'/update/'. $module_id;
								}
								else
								{
									$this->$model->delete($key);
									$redirect = $this->module .'/'. $this->admin;
								}
							}
						}
					}
				}
				status('success','The selected items were deleted successfully.');

				redirect($redirect);

			break;

			case 'batch_transfer_owner':

				if($action == NULL)
				{
					foreach($_POST as $key=>$value)
					{
						if($key != 'batch_action')
						{
							if($key != 'batch_submit')
							{
								if($value == 1)
								{
									$data['data'][$key] = $key;
								}
							}
						}
					}
					$data['action_title'] 	= 'Transfer Content Ownership';
					$data['users'] 			= $this->user_model->find();
					$this->render($data, '', 'core/layout/batch');
				}
				else
				{
					$module_type	= $this->input->post('module_type');
					$class 			= $this->input->post('model');
					$model 			= $class .'_model';
					$this->load->model($module_type .'/'. $model);
					$data['owner_id'] = $this->input->post('owner_id');

					foreach($_POST as $key=>$value)
					{
						if(is_int($key))
						{
							$this->$model->transfer_content_owner($data, $key);
						}
					}
					status('success', message('owner_transfer_success'));
					redirect($module_type .'/'. $class);
				}
			break;

		}	
	}
	
}