MenuItem.php

<?php

/**
 * Class MenuItem
 */
class MenuItem extends DataObject implements PermissionProvider
{
    /**
     * @var array
     */
    private static $db = array(
        // If you want to customise the MenuTitle use this field - leaving blank will use MenuTitle of associated Page
        'MenuTitle'   => 'Varchar(255)',
        // This field is used for external links (picking a page from the dropdown will overwrite this link)
        'Link'        => 'Text',
        // Sort order
        'Sort'        => 'Int',
        // Can be used as a check for adding target="_blank"
        'IsNewWindow' => 'Boolean'
    );

    /**
     * @var array
     */
    private static $has_one = array(
        'Page'    => 'SiteTree', // page the MenuItem refers to
        'MenuSet' => 'MenuSet' // parent MenuSet
    );

    /**
     * @var array
     */
    private static $searchable_fields = array(
        'MenuTitle',
        'Page.Title'
    );

    /**
     * @var array
     */
    private static $summary_fields = array(
        'Menu Title' => 'MenuTitle',
        'Page Title' => 'Page.Title',
        'Link',
        'IsNewWindow'
    );

    /**
     * @var string
     */
    private static $default_sort = 'Sort';

    /**
     * @return array
     */
    public function providePermissions()
    {
        return array(
            'MANAGE_MENU_ITEMS' => 'Manage Menu Items',
        );
    }

    /**
     * @param mixed $member
     * @return boolean
     */
    public function canCreate($member = null)
    {
        return Permission::check('MANAGE_MENU_ITEMS');
    }

    /**
     * @param mixed $member
     * @return boolean
     */
    public function canDelete($member = null)
    {
        return Permission::check('MANAGE_MENU_ITEMS');
    }

    /**
     * @param mixed $member
     * @return boolean
     */
    public function canEdit($member = null)
    {
        return Permission::check('MANAGE_MENU_ITEMS');
    }

    /**
     * @param mixed $member
     * @return boolean
     */
    public function canView($member = null)
    {
        return Permission::check('MANAGE_MENU_ITEMS');
    }

    /**
     * @return FieldList
     */
    public function getCMSFields()
    {
        $fields = new FieldList();

        $fields->push(
            new TextField('MenuTitle', 'Menu Title (will default to selected page title)')
        );

        $fields->push(
            new TreeDropdownField(
                'PageID',
                'Page',
                'Page'
            )
        );

        $fields->push(new TextField('Link', 'Link (use when not specifying a page)'));
        $fields->push(new CheckboxField('IsNewWindow', 'Open in a new window?'));

        $this->extend('updateCMSFields', $fields);

        return $fields;
    }

    /**
     * @return mixed
     */
    public function Parent()
    {
        return $this->MenuSet();
    }

    /**
     * Attempts to return the $field from this MenuItem
     * If $field is not found or it is not set then attempts
     * to return a similar field on the associated Page
     * (if there is one)
     *
     * @param string $field
     * @return mixed
     */
    public function __get($field)
    {
        $default = parent::__get($field);

        if ($default || $field === 'ID') {
            return $default;
        } else {
            $page = $this->Page();

            if ($page instanceof DataObject) {
                if ($page->hasMethod($field)) {
                    return $page->$field();
                } else {
                    return $page->$field;
                }
            }
        }
    }

    /**
     * Checks to see if a page has been chosen and if so sets Link to null
     * This means that used in conjunction with the __get method above
     * calling $menuItem->Link won't return the Link field of this MenuItem
     * but rather call the Link method on the associated Page
     */
    public function onBeforeWrite()
    {
        parent::onBeforeWrite();

        if ($this->PageID != 0) {
            $this->Link = null;
        }
    }
}