switch ($task) {
  case "save":
    save( $option );
    break;
 
  case "delete":
    delete( $option, $id );
    break;
 
  case "new":
    $id = '';
    edit( $option, $id );
    break;
 
  case "edit":
    save( $option, $id[0] );
    break;
 
  case "showText":
    showText( $option );
    break;
}

function save( $option ) {
  global $database;
  $row = new mosHello_world( $database );
  
  if (!$row->bind( $_POST )) {
    echo "<script> alert('".$row->getError()."'); window.history.go(-1); </script>n";
    exit();
  }

  if (!$row->store()) {
    echo "<script> alert('".$row->getError()."'); window.history.go(-1); </script>n";
    exit();
  }

  mosRedirect( "index2.php?option=$option", "Saved" );

}

function edit( $option, $uid ) {
  global $database;
  $row = new mosHello_world( $database );
  $row->load( $uid );
  
  HTML_hello_world::edit( $option, $row );
}

function delete( $option, $cid ) {
  global $database;
  if (!is_array( $cid ) || count( $cid ) < 1) {
    echo "<script> alert('Select an item to delete'); window.history.go(-1);</script>n";
    exit;
  }
  if (count( $cid )) {
    $cids = implode( ',', $cid );
    $database->setQuery( "DELETE FROM mos_hello_world WHERE id IN ($cids)" );
    if (!$database->query()) {
      echo "<script> alert('".$database->getErrorMsg()."'); window.history.go(-1); </script>n";
    }
  }
  mosRedirect( "index2.php?option=$option" );
}

function showText($option) {
  global $database;

  # Do the main database query
  $database->setQuery( "SELECT * FROM mos_hello_world ORDER BY id" );
  $rows = $database->loadObjectList();
  if ($database->getErrorNum()) {
    echo $database->stderr();
    return false;
  }

  HTML_hello_world::showText( $option, $rows );
}

Now let's look at how the file works:

defined( '_VALID_MOS' ) or die( 'Direct Access to this location is not allowed.' );
This makes sure Mambo is calling the file. Very important for security.

require_once($mosConfig_absolute_path."/administrator/components/com_hello_world/class.hello_world.php");
require_once( $mainframe->getPath( 'admin_html' ) );
Calls in the 2 files you will need. class.hello_world.php and admin.hello_world.html.php

switch ($act) {
  default:
   $task = "showText";
   break;
}
Sets a switch so that if you have an $act (action) set, it will redefine it as a $task. You will generally use $act for the main functions such as displaying the text list in this example. $task is used for things such as saving, deleting, etc.

switch ($task) {
  case "save":
    save( $option );
    break;
 
  case "delete":
    delete( $option, $id );
    break;
 
  case "new":
    $id = '';
    edit( $option, $id );
    break;
 
  case "edit":
    save( $option, $id[0] );
    break;
 
  case "showText":
    showText( $option );
    break;
}
The switch that controls your tasks. This switch tells which $task to run which function.

function save( $option ) {
Our first function. This one will save an item we create or edit.

  global $database;
Sets $database as a global variable.

  $row = new mosHello_world( $database );
This creates a new variable named $row which will store the information to insert into the database. It creates a new instance of your mosHello_world class from your class.hello_world.php file.

  if (!$row->bind( $_POST )) {
    echo "<script> alert('".$row->getError()."'); window.history.go(-1); </script>n";
    exit();
  }
If $row doesn't have any values, display the error and go back a window. Unless you are doing something wierd with entering urls on your own, this will never be used :).

  if (!$row->store()) {
    echo "<script> alert('".$row->getError()."'); window.history.go(-1); </script>n";
    exit();
  }
If it can't write to the database, report the error and go back. This will normally only occur if you are having a problem with your database.

  mosRedirect( "index2.php?option=$option", "Saved" );
If all goes well, redirect to your main option window and display the message "Saved".

function edit( $option, $uid ) {
Much of this has been covered, so we will only cover the new parts.

  $row->load( $uid );
After you have your $row defined and set to the mosHello_world class, load the row that contains the $uid value. $uid is set to the value of the $id of the item we want to edit.

  HTML_hello_world::edit( $option, $row );
Sends the $row data to admin.hello_world.html.php to be displayed.

function delete( $option, $cid ) {
Again, I will only cover the concepts not already covered.

  if (!is_array( $cid ) || count( $cid ) < 1) {
    echo "<script> alert('Select an item to delete'); window.history.go(-1);</script>n";
    exit;
  }
This checks to make sure that there has been at least one item selected to be deleted.

  if (count( $cid )) {
    $cids = implode( ',', $cid );
    $database->setQuery( "DELETE FROM mos_hello_world WHERE id IN ($cids)" );
    if (!$database->query()) {
      echo "<script> alert('".$database->getErrorMsg()."'); window.history.go(-1); </script>n";
    }
This checks to make sure there is a value for $cid (an array that holds the $ids of the items to be deleted). If there is a value, it creates a comma delimited list of the ids and stores it in $cids. It then deletes all entries with matching ids. If there is an error deleting, it will go back a screen.

function showText($option) {
This will be the main output function. This is what will create our list to display the text entries. All lines have been explained already.