In order to see how each of the elements that compose the MVC relationship fit each other, below I set up a comprehensive example that demonstrates the concrete interaction between the classes that you learned in the previous sections. Take a look at the following script, which shows how to display a given input string in lowercase:

// display lowercased messages
try{
    $messageController=new MessageController('lowercased');
    $messageKeeper=new MessageKeeper($messageController);
    $messageKeeper->addMessage('This is message 1');
    $messageKeeper->addMessage('This is message 2');
    $messageKeeper->addMessage('This is message 3');
    $messageKeeper->addMessage('This is message 4');
    $messageKeeper->addMessage('This is message 5');
    $viewGenerator=new ViewGenerator($messageKeeper);
    print_r($viewGenerator->generateView());
}
catch(Exception $e){
    echo $e->getMessage();
    exit();
}
/*
displays the following:
Array ( [This is message 1] => this is message 1 [This is message
2] => this is message 2 [This is message 3] => this is message 3
[This is message 4] => this is message 4 [This is message 5] =>
this is message 5 )
*/

See how easy it was to generate lowercase messages? Fine, now examine the following example, which returns an array of uppercase messages:

// display uppercased messages
try{
    $messageController=new MessageController('uppercased');
    $messageKeeper=new MessageKeeper($messageController);
    $messageKeeper->addMessage('This is message 1');
    $messageKeeper->addMessage('This is message 2');
    $messageKeeper->addMessage('This is message 3');
    $messageKeeper->addMessage('This is message 4');
    $messageKeeper->addMessage('This is message 5');
    $viewGenerator=new ViewGenerator($messageKeeper);
    print_r($viewGenerator->generateView());
}
catch(Exception $e){
    echo $e->getMessage();
    exit();
}
/*
displays the following:
Array ( [This is message 1] => THIS IS MESSAGE 1 [This is message
2] => THIS IS MESSAGE 2 [This is message 3] => THIS IS MESSAGE 3
[This is message 4] => THIS IS MESSAGE 4 [This is message 5] =>
THIS IS MESSAGE 5 )
*/

And finally, take a look at the last example, which returns an array of messages in reverse order:

// display reversed messages
try{
    $messageController=new MessageController('reversed');
    $messageKeeper=new MessageKeeper($messageController);
    $messageKeeper->addMessage('This is message 1');
    $messageKeeper->addMessage('This is message 2');
    $messageKeeper->addMessage('This is message 3');
    $messageKeeper->addMessage('This is message 4');
    $messageKeeper->addMessage('This is message 5');
    $viewGenerator=new ViewGenerator($messageKeeper);
    print_r($viewGenerator->generateView());
}
catch(Exception $e){
    echo $e->getMessage();
    exit();
}
/*
displays the following:
Array ( [This is message 5] => This is message 5 [This is message
4] => This is message 4 [This is message 3] => This is message 3
[This is message 2] => This is message 2 [This is message 1] =>
This is message 1 )
*/

That's about it. I think that all the previous examples are quite useful for demonstrating how to implement a simple MVC schema with PHP. Of course, here I'm not showing you a more complex example, due to the fact that I want you to grasp easily the core concepts from the very beginning.

Wrapping up

In this first part of the series, I introduced the key points of how to implement a rather primitive MVC schema with PHP. Hopefully, after seeing the corresponding code samples that I provided here, you'll have a better understanding of how this kind of relationship can be constructed with a few PHP classes.

Over the course of the upcoming tutorial, I'll be taking the MVC schema to the next level by developing a complete web page controller system, where the different views will be determined by selecting several style sheets. You won't want to miss it!