Joomla Component Development Backend

Joomla Component Development

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Joomla Component Development Author

Prabhu Patil

Prepared On

Revision

Approved By

th

18 January, 2009

This document is solely meant for internal use of the designated programmers at “Carmel” development center and is classified as highly confidential. Please ensure that you don’t leave copies of this document on your local disk drives or circulate in any form without explicit permission. The only controlled copy of this document is the on-line version maintained on VSS server. It is the user's responsibility to ensure that any copy of the controlled version is current and complete, and that the obsolete copies are discarded.

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Table of Content Introduction:.........................................................................................................................3 Section 1: The components' table in joomla's database.......................................................4 Section 2: The entry point....................................................................................................5 Section 3 – The backend tasks –The default task................................................................8 Section 3.1 the default controller task (display)..............................................................8 Section 3.2 The model - Getting the students from the DB ..........................................12 The code here it is (Model):.......................................................................................13 Section 3.3 - The view - Listing the students.................................................................24 Here’s the view code (list):........................................................................................24 Section 4 – The backend tasks – The edit task..................................................................37 Section 4.1 – The controller task: edit...........................................................................37 Code for edit method:................................................................................................37 Section 4.2 The model – Getting a student through its id..............................................38 Section 4.3 The view – form to edit the student............................................................38 Section 5: The backend tasks - Save..................................................................................46 Section 5.1 – The controller task: save..........................................................................46 Here’s the code (save() method in studentsController.php): .....................................46 Here is the Code (saveStudent($student) method in …/models/students.php)..........46 Section 5.2 JTABLE......................................................................................................48 Section 5.3 The Model – Adding the save functionality................................................50 Here is the Code (saveStudent($student) method in …/models/students.php)..........50 Section 6: The backend tasks – The add task.....................................................................52 Section 6.1: The controller task: add ............................................................................52 Here’s the add() function in controller code: ............................................................52 Section 6.2: The view - Form to edit the student (revisited).........................................52 Here’s the displayAdd() method in view.php code:...................................................53 Section 6.3: The model – New students.........................................................................53 Here’s the getNewStudent() ..//models/students.php code: ......................................53 Section 7: The backend tasks: The remove task ...............................................................55 Section 7.1: The controller task: remove ......................................................................55 Here is remove() method code in studentsController.php ........................................55 Section 7.2: The model – Deleting students..................................................................55 Here is the deleteStudents() in ..//models/students.php.............................................55 Section 8: Download & Installation...................................................................................58 Unzip Student_Component............................................................................................58 You will find:.................................................................................................................58 Com_students (component)...........................................................................................58 Joomla_Component_Development .doc (Document)....................................................58 jos_components.sql (sql query).....................................................................................58 jos_Students.sql (sql query)...........................................................................................58 Place com_students folder in joomla path ..\\administrator\components\.....................58 Execute jos_components.sql and jos_Students.sql on mysql joomla database............58 That’s it..........................................................................................................................58

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TEST:.............................................................................................................................58 Login to Joomla. Click on component. Find ‘Manage Student’ link. Click on this & Explore...........................................................................................................................58 If you have any queries, please free to mail me. (mailto:[email protected]?subject=Joomla Queries).....................................58 Thank you,.....................................................................................................................58 Prabhu Patil....................................................................................................................58

Component Development with Example: The Backend Introduction: This document is about a Joomla component named "Students" that manage our Students List, Add, Edit and Remove feature. This new version of Joomla (1.5) uses an approach to component development based on the Model-View-Component design pattern. So what is this of the Model View Controller pattern? Well, if you look for it in this book “Design patterns – Elements of Reusable Object Oriented Software” (Erich Gamma, et all), which is probably the most popular book about design patterns, you’ll find this: “MVC consists of three kinds of objects. The Model is the application object, the View is its screen presentation, and the Controller defines the way that the user interface reacts to the user input. Before MVC user interface designs tended to lump these objects together…” So the basic idea is that you have a Model of your data, that is unaware of the views that might exists to represent it, you have one or more views of that model that represent it, and you have a controller, which is responsible for receiving input from the views and updating the model. For creating our Joomla component we’ll have to write a model, a view and a controller for it We have to do the backend, which will allow us to manage our Students: List, Add, Edit and Remove them.

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Section 1: The components' table in joomla's database The first thing we’ll do is to insert a new record in the Joomla’s table that stores the installed components. By doing this you can test your component while you’re developing it, instead of coding it all. To do this you’ll have to have phpmyadmin or you can use the MySQL command line client. In phpmyadmin this is what you have to do: (I’m using version: 5.2.6 of phpmyadmin) 1. Open phpmyadmin and select the database that you’re using for your joomla installation; 2. Select the table jos_components (it might have a different prefix (jos_), you choose the prefix when you install joomla (jos is the default prefix); 3. Click on the insert tab; 4. Fill the Value column with the values: 1. name: Students 2. link: option=com_students 3. admin_menu_link: option= com_students 4. option: com_students And that’s it, the rest of the fields leave them with the default values. Note: If you want to use the MySQL command line client to do this, remember that option is a reserved keyword, so you have to write it like this `option` when you’re writing your SQL insert statement. Here’s what it should look like: INSERT INTO jos_components (name, link, admin_menu_link, `option`) VALUES (‘Students’, ‘option= com_students’, ‘option= com_students’, ‘com_students’) To use this SQL insert statement in the MySQL command line client you have to login, choose the right database (syntax: use DATABASE_NAME; to view the available databases write: show databases; ) and only then you can use it. So now, if you log in to your joomla site back end you should see, under the components tab, the “Students” component. If you click on it, you get an error (404 – Component not

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found). If this is what you got, everything is going well, and we can now start to build our component.

Section 2: The entry point The first thing we have to do is the entry point. But for the backend the naming convention for the file that will contain the code of the entry point is different. Instead of being just the component name followed by “.php”, in the backend it’s: admin.[ComponentName].php. So in our case that will be: admin.students.php and it should be located in: Place where you’ve installed joomla/administrator/components/com_students/admin.students.php the entry’s point code in the backend is exactly the same as the frontend’s, here it is:

execute( JRequest::getVar( 'task' ) ); // Redirect if set by the controller $controller->redirect(); ?> Please note that JPATH_COMPONENT now gives you the path to the backend of our component, in this case: place where you’ve installed joomla/administrator/components/com_students Important this about this piece of code:

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The first line: defined(‘_JEXEC’) or die…: What this means is that if the constant ‘_JEXEC’ is not defined the application exits and the only thing you’ll see is the “Restricted Access” message.

DETAIL 2.1.1: The constant _JEXEC is defined in the index.php file, so if you try to access the students.php file directly, by typing the URL: http://folder where you’ve installed joomla under apache’s htdocs folder/components/com_students/students.php, you’ll get that “Restricted Access” message because _JEXEC won’t be defined. Second line of code, the “require_once(JPATH_COMPONENT.DS.'studentsController.php' );” will load the controller we’ll do next. What you need to know about this is that JPATH_COMPONENT is a joomla constant that contains the path to where your component is, and DS is also a joomla constant that means “Directory Separator” (it’s defined this way to work both in windows and unix environments).

DETAIL 2.1.2: The JPATH_COMPONENT constant contains the frontend’s path to the component if your code is running in the frontend or it has the backend’s path to the component if your code is running in the back end. This is because the JPATH_COMPONENT constant is defined using another constant, the JBASE_PATH constant that contains the path to the frontend if you’re in the frontend or the backend if you’re in the backend. The actual files where theses constants are defined are: JBASE_PATH: index.php (frontend) and administrator/index.php(backend) JPATH_COMPONENT: libraries/joomla/application/component/helper.php (the method you should look for is render Component). JPATH_COMPONENT_SITE: same as above JPATH_COMPONENT_ADMINISTRATOR: same as above These last two constants contain the path to the frontend part of the component and the backend part of the component and are independent of JBASE_PATH. Forth line: “$controller->execute( JRequest::getVar( 'task' ) );” this tells our soon to be created controller which task it should perform. What is important for you to know here is that if task is not defined in the URL the JRequest::getVar(‘task’) returns null, and the execute method from the controller will execute the controller’s default task (the default task is display, I’ll explain this better when we do the controller).

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Last line: “$controller->redirect();” .What you need to know about this is that you can setRedirect in the controller to the URL where the browser should redirect when this method is called. If you don’t use the setRedirect method in the controller, the redirect method just returns false. And that’s the entry point. Don’t try this just yet; it won’t work because we still have to define the controller, the view and the model, which we will do next.

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Section 3 – The backend tasks –The default task Section 3.1 the default controller task (display) Our backend controller will be more complex than our frontend’s. It will have to deal with more tasks: add, edit, remove and display the list of students. I think the easiest way to do this is iteratively. What I mean is that it is easier if we handle each task at a time. For example, if we want to start with the display task, that will list the students, we do the code for the controller, then do the model, do the view and test, and then do the other tasks (this way it is easier to test if everything is going well). It is easier to explain it this way than post all the code from the controller here, describe it, and then do the same for the models and views. So, let’s start with the controller. We’ve called the file studentsController.php we have to put it in the backend folder, so put the file here: Folder where you’ve installed joomla/administrator/components/com_students/studentsController.php Here’s the code that handles the default task (display):
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//This sets the default view (second argument) $viewName = JRequest::getVar( 'view', 'list' ); //This sets the default layout/template for the view $viewLayout = JRequest::getVar( 'layout', 'listlayout' ); $view = & $this->getView($viewName); // Get/Create the model if ($model = & $this->getModel('students')) { //Push the model into the view (as default) //Second parameter indicates that it is the default model for the view $view->setModel($model, true); } $view->setLayout($viewLayout); $view->display(); } }

The default task for the controller is display, so we redefine the display method. This time we want to load a view named list and a model called students. To know how the classes and files for the model and view should be named (see below). The file and class names: • • •

•

•

view file: folder where you’ve installed joomla/administrator/com_students/views/list/view.php view class name: StudentsViewList view layout/template file: folder where you’ve installed joomla/administrator/com_students/views/list/tmpl/listlayout.php (Remember that the file name is lowercase) model file: folder where you’ve installed joomla/administrator/com_students/models/students.php (Remember, that even if you name your model with uppercase character, the file name has to be all lowercase) model class name: StudentsModelStudents

2nd line of code: “jimport('joomla.application.component.controller'); “. What you need to know about this is that it will require_once the file named controller.php located in libraries/joomla/application/component. This file contains the definition of the class JController that we are extending here. The rest is just creating the StudentsController class, that extends JController and redefining the JController’s display method to do exactly what JController’s display

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method does. Why did I do this? Just to tell you about the JController’s display method. This default JController’s display method does this: •

•

Gets the name of the view: o If the parameter view is in the request, for example you have an URL like this: index.php?option=com_students&view=list, the view name will be ‘list’. o If there’s no view parameter in the request the view name will be the controller class name but without ‘Controller’. In our Students component, the controller class name is StudentsController, so the view name is ‘students’. Gets the name of the view’s layout from the request o If the parameter layout is in the request, for example, you have an URL like this: index.php?option=com_students&view=list&layout=listlayout, the view’s layout/template will be called listlayout. o If there is no layout parameter in the request the default layout is called default.

You might be wondering right now, what is this thing, the view’s layout, I haven’t told you about it. Well, I guess the people that developed the JView class(the class that we’ll extend to create our view)decided that it would be nice to have a separate file for the view class definition and the file that will have HTML that actually displays the view (with some php mixed in) . This way you have a view class file, without HTML, and all the HTML mixed with php code in the layout file. I wouldn’t call it layout or template though, because it suggests that you can have two layouts for the same view, and in the MVC, shouldn’t that be two different views? That’s just how I see it anyway… Disagree? Feel free to email me(mailto:[email protected]?subject=should not be two different views (MVC), maybe I didn’t get it right! Now, some other important things that you also need to know about the view’s class name, the view’s file name and the layout’s file name that I haven’t told you: • • •

The view’s class name [ControllerClassNameWithoutController]View[ViewName] The view’s file name is views/[ViewNameLowercased]/view.html.php Layout file name: views/[ViewNameLowercased]/tmpl/[LayoutNameLowercased].php

About the [LayoutNameLowercased].php file name, the lowercase part is really important! Because if you're working in Windows and you decide to name your layout, listLayout, and you forget that the layout file name has to be lowercase (so you name it listLayout.php). What will happen is that it will work ok in your local windows machine, but as soon as you upload the component to your website powered by a Linux server it will stop working, and you'll get an error saying the layout file is not found. Why does this happen? Because file names in Windows environments are not case sensitive, but in

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Linux environments they are. So, don't forget this so that you don't end up banging your head in the wall needlessly. In our case, if we have an URL like this: index.php?option=com_students So, it’s all defaults in this example: •

• •

View Class file: folder where you’ve installed joomla/components/com_students/views/students/view.html.php (the view file name is always view.[DocumentType].php) [I don’t really know about DocumentType] View Class Name: StudentsViewStudents View Layout file: folder where you’ve installed joomla/components/com_students/views/students/tmpl/default.php

Another example: index.php?option=com_students&view=list&layout=listlayout • • •

View Class file: folder where you’ve installed joomla/components/com_students/views/list/view.html.php View Class Name: StudentsViewList View Layout file: folder where you’ve installed joomla/components/com_students/views/list/tmpl/listlayout.php

And these are the secrets behind the naming conventions in Joomla component development. Hope I didn’t forget anything, if you think there is something wrong or unclear feel free to let me know.

DETAIL 3.1.2: Are you wondering why the views’ file and the layout file are under a folder called views and tmpl, respectively? Well I did too, and the answer to that is: the default folder where the controller will look for the views is views, and the default folder where the views will look for layouts is tmpl. Because I’m describing the controller right now, I’ll take this chance to tell you about the default parameters that you can change, in the JController’s contructor. name: the controllers name, this will change all that I described earlier, instead of parsing the name of the controller class to take out the “Controller” part, the name you put here is used instead. • base_path: usually has the path to the component, can’t really remember any reason why you want to change its default value… • default_task: remember I told you that the default task for the controller was display, you can change that here. Note that this is the method that is called if there is no task parameter in the URL. • model_path: default value is base_path/models. This is the folder where the controller will look for the models. Confidential – All rights reserved. • view_path: default value is base_path/views. Here you have it, that’s why if you11 use the defaults you have to place your view files under this folder •

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Did I lose you? Well, I still haven’t finished explaining the JController default display method that we’re using. Next, there’s the how the model file is loaded and how the model class should be named. If you use the default JController’s display method the name of the view and the name of the model have to be the same. Remember, the default view name is the controller’s name without “Controller” if the parameter view is not present in the URL, or, if the parameter view is present in the request URL, then the view name will have the value specified in the url. From now on, I’ll refer to the model name, whose default value is the view name or the view parameter value in the url, as ModelName. So, the file that contains the definition of the model should be named [ModelName].php and be located in models/. The class name should be [ControllerNameWithoutController]Model[ModelName]. The view gets linked to the model, so you can access the model through the view as we’ll see later. So, the default display method, loads the view and model (with the rules I described above), and in the end calls the view’s display method (we’ll look at it when we create the view). So a lot goes on in the Controller that at first glance you might not be aware of. As a curiosity, I’ll show you an alternative to using the JController’s default display method:

Section 3.2 The model - Getting the students from the DB Let’s create our model with a method to load all the students in the database and return them in an array, so that we can display them in the view. Remember, the model is named students. file name: folder where you’ve installed joomla/administrator/components/com_students/models/students.php

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class name: StudentsModelStudents

The code here it is (Model):
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* Constructor * * @since 1.5 */ function __construct(){ parent::__construct(); global $mainframe, $option; // Get pagination request variables $limit = $mainframe->getUserStateFromRequest('global.list.limit', 'limit', $mainframe->getCfg('list_limit'), 'int'); $limitstart = $mainframe->getUserStateFromRequest($option.'.limitstart', 'limitstart', 0, 'int'); // In case limit has been changed, adjust it $limitstart = ($limit != 0 ? (floor($limitstart / $limit) * $limit) : 0);

$this->setState('limit', $limit); $this->setState('limitstart', $limitstart); }

/** * Method to get Students item data * * @access public * @return array

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*/ function getData(){ // if data hasn't already been obtained, load it if (empty($this->_data)) { $query = $this->_buildQuery(); $this->_data = $this->_getList($query, $this->getState('limitstart'), $this>getState('limit')); } return $this->_data; }

/** * Method to get the total number of student items * @access public * @return integer */ function getTotal() { // Lets load the content if it doesn't already exist if (empty($this->_total)) { $query = $this->_buildQuery(); $this->_total = $this->_getListCount($query); }

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return $this->_total; } /** * Method to get a pagination object for the Students * * @access public * @return integer */ function getPagination() { // Lets load the content if it doesn't already exist if (empty($this->_pagination)) { jimport('joomla.html.pagination'); $this->_pagination = new JPagination( $this->getTotal(), $this>getState('limitstart'), $this->getState('limit') ); } return $this->_pagination; }

function _buildQuery() { // Get the WHERE and ORDER BY clauses for the query $where

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= $this->_buildContentWhere();

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= $this->_buildContentOrderBy();

$query = ' SELECT * from #__student AS a ' .$where .$orderby ; return $query; }

function _buildContentOrderBy() { global $mainframe, $option; $filter_order = $mainframe->getUserStateFromRequest( $option.'filter_order','filter_order','a.students_firstname', 'cmd' ); $filter_order_Dir = $mainframe->getUserStateFromRequest( $option.'filter_order_Dir','filter_order_Dir', '', 'word' );

if ($filter_order == 'a.students_firstname'){ $orderby

= ' ORDER BY a.students_firstname'.'

'.$filter_order_Dir; } else { $orderby a.students_firstname , a.ordering ';

= ' ORDER BY '.$filter_order.' '.$filter_order_Dir.',

} return $orderby; }

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function _buildContentWhere() { global $mainframe, $option; $db

=& JFactory::getDBO();

$filter_state $option.'filter_state', );

= $mainframe->getUserStateFromRequest( 'filter_state', '', 'word'

$filter_active = $mainframe->getUserStateFromRequest( $option.'filter_active', 'filter_active', 0, 'int' ); $filter_order = $mainframe->getUserStateFromRequest( $option.'filter_order', 'filter_order', 'a.students_firstname', 'cmd' ); $filter_order_Dir = $mainframe->getUserStateFromRequest( $option.'filter_order_Dir', 'filter_order_Dir', '', 'word' ); $search = $mainframe>getUserStateFromRequest( $option.'search', 'search', '', 'string' ); $search

= JString::strtolower( $search );

$where = array(); if ($search) { $where[] = 'LOWER(a.students_firstname) LIKE '.$db->Quote( '%'.$db->getEscaped( $search, true ).'%', false ); } if ( $filter_state ) { if ( $filter_state == 'P' ) { $where[] = 'a.published = 1';

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} else if ($filter_state == 'U' ) { $where[] = 'a.published = 0'; } } if ($filter_active > 0) { $where[] = 'a.students_active = '.(int) $filter_active; } $where

= ( count( $where ) ? ' WHERE '. implode( ' AND ',

$where ) : '' ); return $where; } function getStudent($id){ $query = 'SELECT * FROM #__student'. ' WHERE id = '.$id; $db = $this->getDBO(); $db->setQuery($query); $student = $db->loadObject();

if ($student === null) JError::raiseError(500, 'Student with ID: '.$id.' not found.'); else return $student; }

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/** * Method to store a Student in the DB * @access

public

*/ function saveStudent($student) { //Parameter not necessary because our model is named StudentsModelStudents (used to ilustrate that you can specify an alternative name to the JTable extending class) //getTable('students'); Here students is not a table name, Table class name $studentTableRow =& $this->getTable('students');

// Bind the form fields to the student table if (!$studentTableRow->bind($student)) { JError::raiseError(500, 'Error binding data'); }

// Make sure the student record is valid if (!$studentTableRow->check()) { JError::raiseError(500, 'Invalid data'); } // Insert/update this record in the db if (!$studentTableRow->store()) { $errorMessage = $studentTableRow->getError(); JError::raiseError(500, 'Error binding data: '.$errorMessage);

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} //If we get here and with no raiseErrors, then everythign went well }

/** * Method that returns an empty student with id 0 * @access

public

*/ function getNewStudent(){

//getTable('students'); Here students is not a table name, Table class name $studentTableRow =& $this->getTable('students'); $studentTableRow->id = 0; $studentTableRow->students_uid = 0; $studentTableRow->students_firstname = ''; $studentTableRow->students_lastname = ''; $studentTableRow->students_grade_id = 0; $studentTableRow->students_email = ''; $studentTableRow->students_street = ''; $studentTableRow->students_city = ''; $studentTableRow->students_state = ''; $studentTableRow->students_zip = ''; $studentTableRow->students_schoolname = '';

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$studentTableRow->students_schoolstate = ''; $studentTableRow->students_timezone = ''; $studentTableRow->students_gender = ''; $studentTableRow->students_phone1 = ''; $studentTableRow->students_phone2 = ''; $studentTableRow->students_p1_firstname = ''; $studentTableRow->students_p1_lastname = ''; $studentTableRow->students_p1_relationship = ''; $studentTableRow->students_p1_phone1 = ''; $studentTableRow->students_p1_phone2 = ''; $studentTableRow->students_p1_email = ''; $studentTableRow->students_p1_email = ''; $studentTableRow->students_p2_firstname = ''; $studentTableRow->students_p2_lastname = ''; $studentTableRow->students_p2_relationship = ''; $studentTableRow->students_p2_phone1 = ''; $studentTableRow->students_p2_phone2 = ''; $studentTableRow->students_p2_email = ''; $studentTableRow->students_type = 0; $studentTableRow->students_active =0; $studentTableRow->students_observedst = 0; $studentTableRow->studetns_deleted = 0; $studentTableRow->students_created_on = '';

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$studentTableRow->students_requirements = '';

return $studentTableRow; }

function deleteStudents($arrayIDs) { $query = "DELETE FROM #__student WHERE id IN (".implode(',', $arrayIDs).")"; $db = $this->getDBO(); $db->setQuery($query); if (!$db->query()){ $errorMessage = $this->getDBO()->getErrorMsg(); JError::raiseError(500, 'Error deleting students: '.$errorMessage); } } } ?>

This code included pagination & filter both we will discuss later.

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Section 3.3 - The view - Listing the students This view will access the model to get the list of students, then make that list of students available for the view’s layout/template and then use the JView default display method to output the html generated by the layout/template. Note that we will be returning from the model not a list of strings, but a list of objects created from what was returned from the database. I’ll call those objects row and you’ll see that each attribute they have corresponds to a database field from the table we’ve created for our component. The attributes will be id, students_firstname, etc. The files and classnames for the view: view file: folder where you’ve installed joomla/administrator/components/com_students/views/list/view.php (Remember that the view file is not called view.html.php because we use the getView method in the controller without specifying its second parameter, the view type). view class name: StudentsViewList layout file: folder where you’ve installed joomla/administrator/components/com_students/views/list/tmpl/listlayout.php

Here’s the view code (list):
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=& JFactory::getDBO(); =& JFactory::getURI();

$filter_state = $mainframe->getUserStateFromRequest( $option.'filter_state', 'filter_state', '', 'word' ); $filter_active = $mainframe->getUserStateFromRequest( $option.'filter_active', 'filter_active', 0, 'int' ); $filter_order = $mainframe->getUserStateFromRequest( $option.'filter_order', 'filter_order', 'a.students_firstname', 'cmd' ); $filter_order_Dir = $mainframe->getUserStateFromRequest( $option.'filter_order_Dir', 'filter_order_Dir', '', 'word' ); $search = $mainframe->getUserStateFromRequest( $option.'search', 'search', '', 'string' ); $search = JString::strtolower( $search ); // Get data $items $total $pagination

from the model = & $this->get( 'Data'); = & $this->get( 'Total'); = & $this->get( 'Pagination' );

// build list of active //$javascript = 'onchange="document.adminForm.submit();"'; //$lists['active'] = JHTML::_('list.active', 'filter_active', $option, intval( $filter_active), $javascript ); // build the active list $db =& JFactory::getDBO(); $sql = 'SELECT DISTINCT students_active FROM #__student'; $db->setQuery($sql); $catlist[] = JHTML::_('select.option', '0', JText::_( 'Select Active -' ), 'id', 'students_active' ); $catlist = array_merge( $catlist, $db->loadObjectList() ); $lists['active'] = JHTML::_('select.genericlist', $catlist, 'active', 'class="inputbox" size="1" onchange="document.adminForm.submit();"','id', 'students_active', intval( $filter_active ) ); // state filter $lists['state']

= JHTML::_('grid.state',

$filter_state );

// table ordering $lists['order_Dir'] = $filter_order_Dir; $lists['order'] = $filter_order; // search filter $lists['search']= $search;

}

//Push data into the template $this->assignRef('user', $this->assignRef('lists', $this->assignRef('items', $this->assignRef('pagination', parent::display();

JFactory::getUser()); $lists); $items); $pagination);

}

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?>

Some new things here: the toolbar code. The first four lines in the display method output the javascript/html that will make up the toolbar for our component (Figure 1).

Figure 1 – Toolbar But it is not too hard to use, so don’t worry, the first line (JToolBarHelper::title) sets the title you’ll see in the toolbar, and the image (generic.png that you can find in folder where you’ve installed joomla/administrator/images). The JToolBarHelper::deleteList(), JToolBarHelper::editListX(), JToolBarHelper::addNewX() add a delete, edit and add buttons to the toolbar. When you press these buttons some javascript is executed that will eventually submit the form we will define in layout/template file for this view. There are a few naming conventions used here that will become clear as soon as I show you an example of the html and javascript generated for one of those buttons. For example the editListX: <span class="icon-32-edit" title="Edit"> Edit First, the html form (defined in the layout/template we’ll do next) has to be named adminForm. This is always true for all forms that you do in the backend. They are always assumed to be named adminForm. Some buttons, like the button generated with editListX, assume you have a hidden field named boxchecked that contains the number of selected items. For example, in our component, this view we’re doing right now will display a list of students, so boxchecked will contain the number of students selected (you don’t have to worry about updating boxchecked, it just has to be defined in the form, and it will be updated automatically. I’ll tell you how that happens when we see the form in the layout/template file).

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We used editListX (and addNewX), which are alternative versions of editList and addNew. The difference between them is that the X versions also calls a javascript function named hideMainMenu that will set the value of a hidden input in the form (if that input exists) named hidemainmenu to 1. When the form is submitted and if hidemainmenu is in the request and has a value of 1, joomla makes the administrator menu (Site Menus Content Components … ) inactive. This is useful when you’re adding or editing (in our case students) because the user will have to click on one of the buttons you put in the toolbar (typically Save and Cancel), because all the other buttons will be inactive. Finally, the buttons call a joomla javascript function named submitbutton that has one parameter called pressbutton. For example, when we press the edit button created by the JToolBarHelper::editListX the submitform will be called with the parameter edit: submitbutton(‘edit’); What this javascript function does is it sets a hidden field named task in the adminForm form (in this example with ‘edit’), and then submits the adminForm. So you see that we also have to have a hidden field named task in our form. We’ll also have to add a hidden field name option that contains the name of the component prefixed by “com_”. This is necessary so that when the form is submitted you get an url equivalent to this (using our component as an example and the edit task): index.php?option=com_students&task=edit (This is not actually true, because we’ll POST the form but the important thing here to remember is that joomla needs to know which component is being executed, hence the option hidden field, and which task is going to be executed for that component, hence the task hidden field). So now, you know that we have to do a layout/template for this view with a form named adminForm and 4 hidden fields named boxchecked, option, task and hidemainmenu. You also know that we have to list the students, and that there are a few naming conventions that we’ll have to follow, we’ll see all that next.

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DETAIL NOTE 3.3.1: You can check the code of JToolBarHelper here: Joomla Component Development folder where you’ve installed joomla/administrator/includes/toolbar.php.

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Here’s a list of the most common button generator methods from JToolBarHelper and what they do to the form (see the toolbar code for all the buttons): back($alt = 'Back', $href = 'javascript:history.back();') – Generates a button that when you click on it makes the browser go to the previous page. addNew($task = 'add', $alt = 'New') – Generates a Add button. (the $alt is the text that is displayed below the button). Fields that have to be defined in the form: task. addNewX($task = 'add', $alt = 'New') same as above. But causes the menu to stay inactive. Fields that have to be defined in the form: task, hidemainmenu. publish($task = 'publish', $alt = 'Publish') Fields that have to be defined in the form: task. publishList($task = 'publish', $alt = 'Publish') – Note that the task string used in this one is the same as the one above. Fields that have to be defined in the form: task, boxchecked. unpublish($task = 'unpublish', $alt = 'Unpublish') Fields that have to be defined in the form: task. unpublishList($task = 'unpublish', $alt = 'Unpublish') Fields that have to be defined in the form: task, boxchecked. editList($task = 'edit', $alt = 'Edit') Fields that have to be defined in the form: task, boxchecked. editListX($task = 'edit', $alt = 'Edit') Fields that have to be defined in the form: task, boxchecked, hidemainmenu. deleteList($msg = '', $task = 'remove', $alt = 'Delete')- When$msg is not empty, a confirm box will display the message $msg. save($task = 'save', $alt = 'Save') Fields that have to be defined in the form: task. cancel($task = 'cancel', $alt = 'Cancel') Fields that have to be defined in the form: task.

DETAIL NOTE 3.3.2: You can check the joomla javascript (hideMainMenu, submitbutton, submitform) in here: folder where you’ve installed joomla/includes/js/joomla.javascript.js

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Here it is: the view’s layout/template. It displays the list of students read from the DB (Figure 2). The file should be here: folder where you’ve installed joomla/administrator/components/com_students/views/list/tmpl/listlayout.php

: lists['state']; echo $this->lists['active']; ?>



>getListFooter(); ?>

items ); $i < $n; $i++) { $row = &$this->items[$i]; $link = JRoute::_( 'index.php?option='.JRequest::getVar('option').'&task=edit&cid[]='. $row->id.'&hidemainmenu=1' ); $checked = JHTML::_('grid.checkedout', $row, $i ); $published = JHTML::_('grid.published', $row, $i ); $ordering = ($this->lists['order'] == 'a.ordering'); //$checked = JHTML::_('grid.id', $i, $row->id); ?> ">

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?>		lists['order_Dir'], $this>lists['order'] ); ?>	lists['order_Dir'], $this>lists['order'] ); ?>	lists['order_Dir'], $this>lists['order'] ); ?>	Confidential – All rights reserved. 29 Joomla Component Development . lists['order_Dir'], $this>lists['order'] ); ?>	lists['order_Dir'], $this>lists['order'] ); ?>	lists['order_Dir'], $this>lists['order'] ); ?>	lists['order_Dir'], $this>lists['order'] ); ?>	lists['order_Dir'], $this>lists['order'] ); ?>
pagination-
pagination->getRowOffset( $i ); ?>	$checked; ?>	user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_firstname); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_firstname); ?>	user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_lastname); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_lastname); ?> Confidential – All rights reserved. 31 Joomla Component Development	. user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_uid); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_uid); ?>	user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_email); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_email); ?>	user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_phone1); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_phone1); ?> Confidential – All rights reserved. 32 Joomla Component Development	. user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_type); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_type); ?>	user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->students_active); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->students_active); ?>	user->get ('id'), $row->checked_out ) ) { echo $this>escape($row->published); } else { ?> <span class="editlinktip hasTip" title="::escape($row->students_firstname); ?>"> "> escape($row->published); ?> Confidential – All rights reserved. 33 Joomla Component Development

Figure 2 – List the students There are a few things you have to know. First, the form action is index.php and the name of the form has to be adminForm. The html table’s css class: adminlist is a css class name used in joomla. The css classes are defined by joomla templates. In this case, because we’re working in the backend, the adminlist css class is defined in a backend template. I don’t think template details are very important here, so just trust me about using that css class, and a few more that I’ll mention. Joomla templates have sufficient material for several tutorials. If you want, have

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a look at the css from the default template for the backend that comes with joomla 1.5 (named khepri), the css is in folder where you’ve installed jooma/administrator/templates/khepri/css, the files that define the class adminlist are general.css and general_rt.css. The table header will display something like this: # [checkbox] First Name (Figure 2). There are a few things you need to know about that checkbox. Its behaviour is that when you click on it, you select/deselect all items (in our case students). This will work if we respect joomla’s naming conventions for the checkboxes. First, this checkbox has to be named toggle, and it’s onclick event handler has to be checkAll([Number of items listed]) (in our case, the number of items are the students). The checkAll javascript method is defined in folder where you’ve installed joomla/includes/js/joomla.javascript.js, and what it does is that it checks to see if a checkbox named toggle inside a form named adminForm is checked or not, and then it goes through the checkboxes with id cbX, where X goes from 0 to the number you pass as argument to checkAll-1, and checks or unchecks them depending on the of checkbox named toggle being checked or not. So now you know that the checkboxes to select each individual item have to have an id: cb0, cb1, cb2, etc. But fortunately, since joomla 1.5, you don’t have to worry about that because the code: JHTML::_('grid.id', $i, $row->id); generates that for you. JHTML is used to generate the html for several html elements

DETAIL NOTE 3.3.3: If you see the actual HTML generated when you do JHTML::_('grid.id', $i, $row->id); you’ll see that the name of the checkboxes is actually cid[]. This is a php thing: when you add ‘[]’ to the name of a checkbox and you have several checkboxes with that same name followed by ‘[]’ you can read an array from the request with the value of the checked checkboxes. In our case, when we read cid from the request we’ll get an array that contains the values of the checked checkboxes.

Each of the students displayed is a link, that when you click on it redirects you to the url: index.php?option=com_students&task=edit&cid[]=ID_OF_THE_ROW_WE_WANT_TO _EDIT&hidemainmenu=1. We’re using JRoute’s ‘_’ function to build the url. We should do that because the ‘_’ method from JRoute rewrites the url to a Search Engine Friendly(SEF) form if SEF is enabled in Joomla (To enable SEF go to Site->Global Configuration). However, SEF doesn’t work on the backend so you won’t see any difference in the url, but still it’s good practice to use it because if you want to reuse some of the code in the frontend you won’t have to worry about the urls .The hidemainmenu parameter is set to 1 in the url so that the joomla’s administrator menu stays disabled when editing (remember, that also happens when we click the edit button because we use JToolBar::editListX : the X version of editList).

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About the actual listing of the students (the foreach’s code), we’re using a trick to change the css class of every . The css classes row0 and row1 have different background colors making it easier for you to distinguish between each item in the list (in our case, each student). The rest is each table row displays the student’s id, followed by a checkbox that was generated by JHTML::_('grid.id', $i, $row->id); and then the actual student, in the form of a link that, when pressed will create a request for our backend’s component with the task edit and with the parameter cid (that will be an array) with the value of the id of the student we want to edit (we still have to code the edit task). DETAIL NOTE 3.3.4: This note is about how the boxchecked hidden field is updated. The code generated by JHTML::_('grid.id', $i, $row->id); is something like this: . The javascript isChecked method is the one that updated boxchecked hidden input field. What it does is if the checkbox is being checked it adds 1 to the boxchecked adminForm’s hidden input, if it is being unchecked it subtracts 1. You can see the code for isChecked here: folder where you’ve installed joomla/includes/js/joomla.javascript.js.

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Section 4 – The backend tasks – The edit task Section 4.1 – The controller task: edit Now let’s do the edit task. To do that we just have to add a method named edit to our controller that will load a view named studentForm, with a layout/template named studentformlayout. We will use the same model we used for listing the students although we’ll add a new method that will return an object that represents a row in the students table in the database (we’ll look at that in Section 4.2). I’m not reading the viewname and layout from the request in this task, I just make the view name and layout fixed to studentForm and studentformlayout respectively. In this task we’ll read the id of the student we want to edit. There is a detail about reading the id from the request. Remember that when we listed the student we put a link in each one: index.php?option=com_student&task=edit&cid[]=ID. Where ID is the actual ID for the student we want to edit. You might be asking yourself right now why did I used cid[] as a parameter. Especially because if we’re just editing one student, why do we need to put it in an array? The answer to that is: it’s because of the Edit button in the toolbar. When you click on it, it submits the form that has the list of student, and the selected students will go in the request in the cid[] parameter. So, that’s why we called the parameter with the id of the student cid[] , so that we could handle both cases (clicking on the link and clicking the edit button in the toolbar) the same way. We’ll call a method named displayEdit in the view and pass the id of the student as a parameter to it (we’ll do the view’s displayEdit method in Section 4.3). Remember that our controller file is named studentsController.php, and it should be located in folder where you’ve installed joomla/administrator/components/com_students/studentsController.php. Code for edit method: function edit(){ //getVar(PARAMETER_NAME, DEFAULT_VALUE, HASH, TYPE) //The HASH is where to read the parameter from: //The default is its default value: getVar will look for the parameter in //GET, then POST and then FILE $cids = JRequest::getVar('cid', null, 'default', 'array' ); //Reads cid as an array if($cids === null){ //Make sure the cid parameter was in the request JError::raiseError(500, 'cid parameter missing from the request'); } $studentId = (int)$cids[0]; //get the first id from the list (we can only edit one student at a time) $view = & $this->getView('studentForm'); // Get/Create the model if ($model = & $this->getModel('students')) { //Push the model into the view (as default)

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//Second parameter indicates that it is the default model for the view $view->setModel($model, true); } $view->setLayout('studentformlayout'); $view->displayEdit($studentId); }

Section 4.2 The model – Getting a student through its id

We have to add a method to our model that gets a student from the database based on its id. If you remember the code that we did for the default task (display) that displays a list of the students read from the database, you’ll remember that in that list each student has a link. Something like this: index.php?option=com_students&task=edit&cid[]=1. Where, in this example the 1 is the id of the student we want to edit. So our new method for the model will do just that: get the student from the database with a specific id. Let’s call that method getStudent. Remember that our model file is named students.php and that it is located in folder where you’ve installed joomla/administrator/components/com_students/models/students.php Here’s the code getStudents() method: function getStudent($id){ $query = 'SELECT * FROM #__student'. ' WHERE id = '.$id; $db = $this->getDBO(); $db->setQuery($query); $student = $db->loadObject(); if ($student === null) JError::raiseError(500, 'Student with ID: '.$id.' not found.'); else return $student; }

Section 4.3 The view – form to edit the student

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This view we’re about to do will display a form that will allow us to edit a student (Figure 3) . We’ll create a method named displayEdit that gets as a parameter the id of the student we want to edit, then we use the getStudent method from the model associated with this view to get the actual student from the database and then display it in the form in the layout/template. This view will have two buttons on its toolbar: Save and Cancel. This view will have to be located in: folder where you’ve installed joomla/administrator/components/com_students/views/studentForm/view.php The view’s class name is: StudentsViewStudentForm And the layout/template file: joomla/administrator/components/com_students/views/studentForm/tmpl/studentformlay out.php Here’s the code for the view: Edit]'); JToolBarHelper::save(); JToolBarHelper::cancel(); $model = $this->getModel(); $student = $model->getStudent($studentId); $this->assignRef('student', $student); parent::display(); } function displayAdd(){ JToolBarHelper::title('Student'.': [<small>Add]'); JToolBarHelper::save(); JToolBarHelper::cancel(); $model = $this->getModel(); $student = $model->getNewStudent(); $this->assignRef('student', $student); parent::display();

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} } ?>

Remember that the layout/template for this view is named studentformlayout and should be located in: folder where you’ve installed joomla/administrator/com_students/views/studentForm/tmpl/studentformlayout.php The code is here:

Student Details

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First Name *
Last Name *
Gender *
Email ID *
Street
City
State
ZIP
School State *
Phone 1
Phone 2
Time Zone *
Student Type
Status

Parent/Guardian

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First Name *
Last Name *
Relationship
Phone 1 *
Phone 2
Email Address *

Figure – 3 The Edit Form

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Remember that we used the Save and Cancel buttons in the toolbar, the Save button causes this form to be submitted with the hidden field task with value ‘save’ and the Cancel button submits the form with the hidden field task with value ‘cancel’. There is an important detail here, which is: the form has to have inputs with the same name as the fields in our jos_students table, that’s why there is a hidden field named id. When we do the save task it will be clear why.

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Section 5: The backend tasks - Save Section 5.1 – The controller task: save When we edit a student and click on the save button the form we just did before is going to be submitted with the task parameter set to save. That will cause the save task to be executed in the controller. So we need to do the method to handle that task, and that method has to be named save. So let’s add that method to our backend controller, it will read the data posted by the form we did for the studentForm view. Then it will use a method in the model that will get that post data as a parameter and will use it to update the database record that corresponds to the student we’re editing (we need to add that method to our model, it is named saveStudent). Finally, after using the model to save the edited student we’ll use the JController’s method setRedirect to make joomla redirect to the page where the students are listed (our components default task, display).

DETAIL NOTE 5.1.1: If you’re wondering how setRedirect will redirect you to the link you pass as a parameter look at our entry point file, and you’ll see that at the end a method named redirect from the controller is executed. That method is what actually causes the browser to redirect to the link we supply as a parameter to setRedirect.

We are editing controller file, located in: folder where you’ve installed joomla/administrator/com_student/studentsController.php

Here’s the code (save() method in studentsController.php): function save(){ $student = JRequest::get( 'POST' ); $model = & $this->getModel('students'); $model->saveStudent($student); $redirectTo = JRoute::_('index.php?option='.JRequest::getVar('option').'&task=display'); $this->setRedirect($redirectTo, 'Student Saved!'); }

Here is the Code (saveStudent($student) method in … /models/students.php) /** * Method to store a student in the DB */ function saveStudent($student)

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{ //Parameter not necessary because our model is named StudentsModelStudents (used to illustrate that you can specify an alternative name to the JTable extending class) //getTable('students'); Here students is not a table name, Table class name $studentTableRow =& $this->getTable('students'); // Bind the form fields to the student table if (!$studentTableRow->bind($student)) { JError::raiseError(500, 'Error binding data'); } // Make sure the student record is valid if (!$studentTableRow->check()) { JError::raiseError(500, 'Invalid data'); } // Insert/update this record in the db if (!$studentTableRow->store()) { $errorMessage = $studentTableRow->getError(); JError::raiseError(500, 'Error binding data: '.$errorMessage); } }

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Section 5.2 JTABLE To have our saveStudent method in the model we’re going to use an instance of a class we’ll do that extends JTABLE. JTABLE is a class we can extend that has methods that help us interact with the database, especially if we want to update or add records to a database table. To use the functionalities that JTABLE has we have to create a class that extends JTABLE and has a direct correspondence between the names of its attributes and the names of the fields in the database table we’re dealing with. Using our jos_students table as an example, the class that we’re going to write that extends JTABLE has many attributes, for example named id, students_firstname,students_lastname, etc., which correspond to the jos_students database table fields with the same name. We also have to specify in the constructor which of the fields is the key for the database and also the table’s name. The JModel specifies methods to get instances of JTABLE following some naming conventions. First, the default location for JTABLE files is, in the backend: folder where you’ve installed joomla/admistrator/components/com_students/tables; in the frontend it’s the same without administrator (you can change the default location in the model’s constructor). You can use a JModel’s method named getTable without parameters to get the class that extends JTABLE following JModel’s naming conventions for table classes. The convention is: •

•

The class extending JTABLE should be named Table[ModelName], where [ModelName] is the model’s name from where we’re using the JModel’s gettable method without parameters. Remember that the model’s class name is build by: [ControllerName]Model[ModelName]. The class that extends JTable should be located in folder where you’ve installed joomla/administrator/components/[COMPONENT_NAME]/tables where [COMPONENT_NAME] is the name of the component where our model is. And should be named [ModelName].php (the file name has to be in lowercase).

If you want, you can specify a name in the JModel’s getTable method, for example getTable(‘Mytable’), this tries to get an instance for a class named TableMyTable located in joomla/administrator/components/[COMPONENT_NAME]/tables/mytable.php for the backend (the same for the frontend without administrator.)

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DETAIL NOTE 5.2.1: To change the default location of the classes that extend JTable you have to override the default constructor ofthe model class you’re using, and specify in the config array, that the constructor gets as argument, a parameter named table_path. For example, if we want to change the tables folder in our model for the students (in the backend) we would add this code to our model file located in: folder where you’ve installed joomla/administrator/components/com_students/models/students.php function __construct(){ parent::__construct(array('table_path'=>JPATH_COMPONENT.DS.'myTablesFolder') ); }

Here’s the code for the class that will extend JTable that we will be using to add and update students in our students’ database table, it has to be located in: folder where you’ve installed joomla/administrator/components/com_students/tables and the file will be named students.php:
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} ?>

Section 5.3 The Model – Adding the save functionality We’re adding a new method to our model named saveStudent that, if you remember from the controller’s code, we’re invoking there and passing a parameter to it with the data we’re getting from the request (that will contain the values from the inputs of the from that is outputted by the studentForm view). This is where we’ll use the functionalities offered by JTable. I’ll show you the code and then talk a little bit about the methods we’re using from JTable. Remember, this file is located in: folder where you’ve installed joomla/administrator/com_students/models/students.php

Here is the Code (saveStudent($student) method in … /models/students.php) /** * Method to store a student in the DB */ function saveStudent($student) { //Parameter not necessary because our model is named StudentsModelStudents (used to illustrate that you can specify an alternative name to the JTable extending class) //getTable('students'); Here students is not a table name, Table class name $studentTableRow =& $this->getTable('students'); // Bind the form fields to the student table if (!$studentTableRow->bind($student)) { JError::raiseError(500, 'Error binding data'); } // Make sure the student record is valid if (!$studentTableRow->check()) { JError::raiseError(500, 'Invalid data'); } // Insert/update this record in the db if (!$studentTableRow->store()) { $errorMessage = $studentTableRow->getError(); JError::raiseError(500, 'Error binding data: '.$errorMessage); } }

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The $student parameter will be an array that will contain the values from the input fields from the form (that we did in the studentForm view) indexed by the names of the inputs. The JTable’s bind method we’re using ($studentTableRow->bind($student)) uses reflection to get all the attributes from the class, and then sets them with the values from the array passed as a parameter that have a key with the same name as the attributes in the class. This gets really simple with an example. Imagine our TableStudents class that extends JTable. It has mnay attributes: id, students_firstname, students_lastname, etc.,. And remember that the form from the studentForm view has among other form inputs, an input named id and student. What bind does is it sets the attribute id with the value from the form input id, and the same for student. DETAIL 5.3.1: Doc. page for JTable::bind: http://dev.joomla.org/component/option,com_jdwiki/Itemid,/id,references:joomla.framework:table:jtable-bind/ If you look at bind’s signature: boolean bind ( $from, $ignore ) you’ll notice that it has a second parameter. What it’s for is to specify a list of attributes to be ignored in the binding process. If for some reason you have attributes in your table class that you don’t want to update with the values from $from, you put them in $ignore. Also note that if an attribute is in the table class, but not in $from, no error is produced and bind still returns true. After the bind we do the check. What the JTable’s check method does is … well it just returns true. I just put it there so I could tell you about it. The idea behind the check method is that you should override it when you extend JTable, and make it return true if the attributes are valid and false otherwise Finally, we store. What store does is it inserts a new record in the database if the attribute that represents the table key is 0 (in our case if the Tablestudent id attribute is 0 a new record is inserted), or it updates the record whose primary key has the same value as the value of the attribute we specify as key in the JTable’s class constructor (in our case, TableStudent id attribute with value X not 0, will cause an update to the student with id X).

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Section 6: The backend tasks – The add task Section 6.1: The controller task: add

For the add task we’re doing something very similar to the edit task. This is the task that will be executed when you click on the toolbar’s Add button when our component is displaying the list of students (default display task). What we will do in the controller code is we will add a method named add that will get the model named students and the view named studentForm and call a method from that view named disaplyAdd that we’ll do later. We need to add method to our controller file located in folder where you’ve installed joomla/administrator/com_students/studentsController.php

Here’s the add() function in controller code: function add(){ $view = & $this->getView('studentForm'); $model = & $this->getModel('students'); if (!$model){ JError::raiseError(500, 'Model named students not found'); } $view->setModel($model, true); $view->setLayout('studentformlayout'); $view->displayAdd(); }

Now let’s do add the displayAdd method to the view named studentForm.

Section 6.2: The view - Form to edit the student (revisited)

We have to add a method named displayAdd that has no arguments to the view named studentForm. What this method will do is, it will call a method from the model named getNewStudent (that we’ll do later) that returns an “empty” student with id 0, and then it’s the same thing as we did for editing a student. The only difference is that we will be editing a student with id 0, and the actual student will be an empty string. We’re editing the view named studentForm which is located here:

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folder where you’ve installed joomla/administrator/components/com_students/views/studentForm/view.php

Here’s the displayAdd() method in view.php code: function displayAdd(){ JToolBarHelper::title('Student'.': [<small>Add]'); JToolBarHelper::save(); JToolBarHelper::cancel(); $model = $this->getModel(); $student = $model->getNewStudent(); $this->assignRef('student', $student); parent::display(); }

That’s it for the view, now let’s do the model.

Section 6.3: The model – New students We have to add the getNewStudent method to the students model. What this method will do is it will get an instance form the table class (the one that implements JTBALE) and set that instance’s id attribute to 0 and the student attribute to the empty string. We’re editing the students model file located in: folder where you’ve installed joomla/administrator/components/com_students/models/students.php

Here’s the getNewStudent() ..//models/students.php code: /** * Method that returns an empty student with id 0 */ function getNewStudent(){ //getTable('students'); Here students is not a table name, Table class name $studentTableRow =& $this->getTable('students'); $studentTableRow->id = 0; $studentTableRow->students_uid = 0; $studentTableRow->students_firstname = ''; $studentTableRow->students_lastname = ''; $studentTableRow->students_grade_id = 0; $studentTableRow->students_email = ''; $studentTableRow->students_street = ''; $studentTableRow->students_city = ''; $studentTableRow->students_state = ''; $studentTableRow->students_zip = ''; $studentTableRow->students_schoolname = ''; $studentTableRow->students_schoolstate = ''; $studentTableRow->students_timezone = '';

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$studentTableRow->students_gender = ''; $studentTableRow->students_phone1 = ''; $studentTableRow->students_phone2 = ''; $studentTableRow->students_p1_firstname = ''; $studentTableRow->students_p1_lastname = ''; $studentTableRow->students_p1_relationship = ''; $studentTableRow->students_p1_phone1 = ''; $studentTableRow->students_p1_phone2 = ''; $studentTableRow->students_p1_email = ''; $studentTableRow->students_p1_email = ''; $studentTableRow->students_p2_firstname = ''; $studentTableRow->students_p2_lastname = ''; $studentTableRow->students_p2_relationship = ''; $studentTableRow->students_p2_phone1 = ''; $studentTableRow->students_p2_phone2 = ''; $studentTableRow->students_p2_email = ''; $studentTableRow->students_type = 0; $studentTableRow->students_active =0; $studentTableRow->students_observedst = 0; $studentTableRow->studetns_deleted = 0; $studentTableRow->students_created_on = ''; $studentTableRow->students_requirements = ''; return $studentTableRow; }

Why are we doing this? Remember when I explained how the JTable’s store method worked? That when the attribute associated with the table’s primary key was 0 the store method would insert a new record in the database. That’s what happening here, it is like you’re editing a student with id 0, but when you click the save button, and the save task is executed, you get a new record in the database.

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Section 7: The backend tasks: The remove task Section 7.1: The controller task: remove

To do the remove task we have to get the id of the student we want to remove (like we did for the student to edit, in the edit task). Then we’ll call a method from the model named deleteStudents to which we will supply the array with the ids of the student as a parameter (we’ll do deleteStudents later), and then use the JController’s setRedirect method to redirect to the list of the students. We’re editing the controller’s class located in: folder where you’ve installed joomla/administrator/com_students/studentsController.php

Here is remove() method code in studentsController.php function remove(){ $arrayIDs = JRequest::getVar('cid', null, 'default', 'array' ); //Reads cid as an array if($arrayIDs === null){ //Make sure the cid parameter was in the request JError::raiseError(500, 'cid parameter missing from the request'); } $model = & $this->getModel('students'); $model->deleteStudents($arrayIDs); $redirectTo = JRoute::_('index.php?option='.JRequest::getVar('option')); $this->setRedirect($redirectTo, 'Deleted...'); }

Section 7.2: The model – Deleting students Where doing the deleteStudents method in our students model that gets an array with the id’s of the students to be deleted as input. We’re using php’s implode method that has two arguments, the separator and the array. Imagine you use implode with arguments (‘,’, array(‘a’,’b’,’c’)) you’d get a string like this: ‘a,b,c’. We’re editing the model named students’ file, located in: folder where you’ve installed joomla/administrator/com_students/models/students.php

Here is the deleteStudents() in ..//models/students.php function deleteStudents($arrayIDs) { $query = "DELETE FROM #__student WHERE id IN (".implode(',', $arrayIDs).")";

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$db = $this->getDBO(); $db->setQuery($query); if (!$db->query()){ $errorMessage = $this->getDBO()->getErrorMsg(); JError::raiseError(500, 'Error deleting students: '.$errorMessage); } }

Note that we’re using the getErrorMsg method from JDatabase to get the error message. If there’s an error while the query is being executed (query method) getErrorMsg returns the SQL error that describes what happened.

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Section 8: Download & Installation http://cide9dd1034313be3eb.skydrive.live.com/browse.aspx/Joomla?authkey=gjPSvFj48xQ% 24 Use this link to download student_component.

Unzip Student_Component. You will find: •

• • •

Com_students (component) Joomla_Component_Development .doc (Document) jos_components.sql (sql query) jos_Students.sql (sql query)

Place com_students folder in joomla path ..\\administrator\components\ Execute jos_components.sql and jos_Students.sql on mysql joomla database. That’s it.

TEST: Login to Joomla. Click on component. Find ‘Manage Student’ link. Click on this & Explore. If you have any queries, please free to mail me. (mailto:[email protected]?subject=Joomla Queries) Thank you, Prabhu Patil

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