Event.php

<?php
namespace App;

use SilverStripe\ORM\DataObject;
use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\TextField;
use SilverStripe\Forms\TextareaField;
use SilverStripe\Versioned\Versioned;
use SilverStripe\Control\Controller;

class Event extends DataObject
{
    private static $summary_fields = [
        'Title' => 'Title of Event',
        'Description' => 'Event Details'
    ];

    private static $has_one = [
        'EventsPage' => EventsPage::class
    ];

    private static $versioned_gridfield_extensions = true;

    private static $extensions = [
        Versioned::class,
    ];

    private static $db = [
        'Title' => 'Varchar',
        'Description' => 'Text',
    ];

    private static $searchable_fields = [
        'Title'
    ];

    public function getCMSFields()
    {
        $fields = FieldList::create(
            TextField::create('Title'),
            TextareaField::create('Description')
        );

        return $fields;
    }

    public function Link()
    {
        return $this->EventsPage()->Link('events/show/'.$this->ID);
    }

    public function LinkingMode()
    {
        return Controller::curr()->getRequest()->param('ID') == $this->ID ? 'current' : 'link';
    }
}

EventAdmin.php

<?php
namespace App;

use SilverStripe\Admin\ModelAdmin;

class EventAdmin extends ModelAdmin {

    private static $menu_title = 'Events';

    private static $url_segment = 'events';

    private static $managed_models = [
        Event::class
    ];

}

EventsPage.php

<?php
namespace App;

use SilverStripe\Control\HTTPRequest;

class EventsPage extends \Page {

    private static $has_many = [
        'Events' => Event::class,
    ];

    private static $owns = [
        'Events'
    ];

}

class EventsPageController extends \PageController {

    public function LatestEvents()
    {
        return Event::get()
            ->limit(6);
    }

    private static $allowed_actions = [
        'show'
    ];

    public function show(HTTPRequest $request)
    {
        $event = Event::get()->byID($request->param('ID'));

        if(!$event) {
            return $this->httpError(404,'That event could not be found');
        }

        return [
            'Event' => $event
        ];
    }

}