silverstripe LeftAndMain 2. Configuring HelloWorldLeftAndMain.php

Example

If you haven't already lets simply start this file of with:

class HelloWorldLeftAndMain extends LeftAndMain {

}

Configure

The first thing you should do, is define the $url_segment that will be used to access the interface, and the title ($menu_title) that will appear in the side navigation menu of the administration panel:

private static $url_segment = 'helloworld';
private static $menu_title  = 'Hello World';

The following configuration variable(s) are optional and not used in this guide:

private static $menu_icon   = 'helloworld/path/to/my/icon.png';
private static $url_rule    = '/$Action/$ID/$OtherID';

Adding Stylesheets and Javascript

LeftAndMain allows you to override the init method in it's parent, we can use this to require specific files for our interface. Undoubtedly you should always need to require a CSS stylesheet that will style the elements for your user interface.

As a tip, it's recommended to never rely on the CSS classes provided by the CMS as these are subject to change without notice and will subsequently destroy the Look & Feel of your UI (for example, 3.* to 4.* has seen a complete makeover of the interface therefore any CSS classes you relied on in 3.* need to be restyled for conversion to 4.*)

So lets add our helloworld/css/styles.css file:

public function init() {
    parent::init();

    Requirements::css('helloworld/css/styles.css');
    //Requirements::javascript('helloworld/javascript/script.min.js');
}

We don't need any Javascript functionality for this example but in the above I have included how one would achieve adding Javascript a file using the Requirements class.

After which you can adopt what you have been used to when dealing Page_Controller such as $allowed_actions etc with one notable difference, however

You CANNOT override index().

Instead index() is assumed as HelloWorldLeftAndMain_Content.ss and from there, it's required to deal with the indexes display via template functions (see example below)

Complete Code

class HelloWorldLeftAndMain extends LeftAndMain {
    private static $url_segment = 'helloworld';
    private static $menu_title  = 'Hello World';
    private static $allowed_actions = array(
        'some_action'
    );

    public function init() {
        parent::init();

        Requirements::css('helloworld/css/styles.css');
        //Requirements::javascript('helloworld/javascript/script.min.js');
    }

    public function Hello($who=null) {
        if (!$who) {
            $who = 'World';
        }

        return "Hello " . htmlentities($who);
    } 
}