6CC001 Workshop - week 04

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Your job today is to implement a blog similar to this one:

• http://mi-linux.wlv.ac.uk/~in9352/OO/blog/index.php

The different steps are:

1. Step 1 - Create and populate database
2. Step 2 - Create the index.php file, front controller and registry class
3. Step 3 - Handling user request and creating appropriate command
4. Step 4 - Accessing the database
5. Step 5 - Creating our first view
6. Step 6 - Adding messages
7. Step 7 - Deleting messages

Let's take it one step at a time... and remember: read and understand the code before pasting it into your text editor!

Step 6 - Adding messages

Next, let’s add a command to add blog messages. You might have noticed above that our “add messages” link (see above) points to “index.php?cmd=BlogAddForm”

So first, you need a new command called “Command_BlogAddForm”. It doesn’t do much, it simply displays the view containing the form. Here is the code:

// Command_BlogAddForm.php

//############################################################################
// SearchVenueCommand class
//############################################################################
class Command_BlogAddForm extends Command
{
  //############################################################################
  // doExecute
  //############################################################################ 
  function doExecute(Request $request)
  {
    // Include view
    include("views/add_form.php");
  }
}

And here is the view containing the form:

<!-- views/add_form.php -->

<?require_once("view_helper.php");?>

<?ViewHelper::DisplayHeader("Add message");?>

<h1>Blog add form</h1>

<p>Please fill in the fields</p>

<form action="index.php?cmd=BlogAdd" method="post">
  Title:<br><input name="title">
  <br>
  Message:<br><textarea name="message"></textarea>
  <br>
  <input type="submit" value="Add">
</form>
    
<?ViewHelper::DisplayFooter();?>

Again note that the "action" attribute of the <FORM> above points to "index.php?cmd=BlogAdd". So we need another action responsible for reading the user data from the form, and creating a new record in the database... here it is!

// Command_BlogAdd.php

//############################################################################
// Command_BlogAdd class
//############################################################################
class Command_BlogAdd extends Command
{
  //############################################################################
  // doExecute
  //############################################################################ 
  function doExecute(Request $request)
  {
    // Get data from request
    $title = $request->getProperty('title');
    $message = $request->getProperty('message');
    
    // Create manager object
    $manager = new ManagerMessage();    
    
    // Add to database
    $manager->addMessage($title, $message);
    
    // Redirect to index
    header("location:index.php");
  }
}

Note: This action doesn't have a view. It simply redirects the user to the index of the forum.

Checkpoint

You should now be able to add new messages... try it!

Step 7 - Deleting messages

Finally, let’s create a new action in charge of message deletion.

Again if you browse the mouse over the “delete this message” links, you will see URLs such as “index.php?cmd=BlogDelete&id=19”

So we need a new Command_BlogDelete class. Here is the code:

// Command_BlogDelete.php

//############################################################################
// SearchVenueCommand class
//############################################################################
class Command_BlogDelete extends Command
{
  //############################################################################
  // doExecute
  //############################################################################ 
  function doExecute(Request $request)
  {
    // Get data from request
    $id = $request->getProperty('id');
    
    // Create manager object
    $manager = new ManagerMessage();    
    
    // Add to database
    $manager->deleteMessage($id);
    
    // Redirect to index
    header("location:index.php");
  }
}

Nothing too complicated here...

Checkpoint

You should now be able to delete messages.

Note: It is always better practice to ask users to confirm deletion first... but you can do that bit ;)