SilverstripeCheatSheet.php

<?php 
// if you add a new file...
// make sure the '<' is the FIRST THING IN THE FILE
// no whitespace!! nothing! '<' ONLY OR THE WHOLE DANG SITE BREAKS

// call your class something reasonable. use 'extends' to get all the properties
// of another type of page, or just Page if it's its own new thing

class MyNewPagetype extends Page {

    // $db - for data that you can represent with a single field
    public static $db = array(
        'SimpleText' => 'Varchar(40)',     // string, max 40 characters
        'Byline' => 'Varchar(200)',        // string, max 200 characters
        'Wysiwyg' => 'HTMLText',           // it's obvious!
        'Counter' => 'Int',                // a number
        'FlashyModeEnabled' => 'Bool',     // true/false
    );

    // $has_one - for links to other objects!
    public static $has_one = array(
        'HeroImage' => 'Image',             // an image
        'CallToActionPage' => 'Page',       // a link to another page 
        'SignupPage' => 'SignupPage',       // you can restrict by pagetype
    );
    // (note that it's fine to use the same name for field and type)
  
    // in a template, these properties will all be available just by their name:
    // $SimpleText, $Byline, $Wysiwyg, $HeroImage, etc
    // or some more complex examples:  
  
    // <a href="$SignupPage.Link">$SignupPage.MenuTitle</a>
    
    // <% if Byline %>
    //      <p class="byline">$Byline</p>
    // <% end_if %>
    
    // -- note that you don't need the $ inside an <% if %> !
    
    // there's also has_many but it's probably a bit out of scope for this cheatsheet
    public static $has_many = array();  
   
    // here's where we add the fields to the admin interface
    public function getCmsFields() {
        $f = parent::getCmsFields();    // get the field from the parent type
    
        // add one field. 
        $f->addFieldToTab('Root.Main', TextField::create('SimpleText', 'Simple text'));
      
        // 'Root.Main' is the tab to add to.
        // TextField (and most fields) take 2 parameters: 
        //  - the data field to hook into
        //  - the label to put on the field
        // They will usually be pretty much the same.

        // add multiple fields at once
        $f->addFieldsToTab('Root.Main', array(
            TextField::create('Counter', 'Counter'),    // fine to use a text field for int
            CheckboxField::create('FlashyModeEnabled', 'Flashy mode'),
            HTMLEditorField::create('Wysiwyg', 'Edit your content here')
        ));
      
        // you can add a third parameter to addField(s)ToTab that is the name of another field
        // that already exists.
        // addFieldToTab will now add the new field _before_ that field in the CMS.
        // (otherwise it'll add it at the bottom of the tab)
        $f->addFieldToTab('Root.Main', TextField::create('Byline', 'Byline'), 'SimpleText');
      
        // upload a file (the UploadField can handle anything, but because it's defined as
        // an image in $has_one, Silverstripe will automatically restrict uploads to images for us
        $f->addFieldToTab(
            'Root.Main',
            UploadField::create('HeroImage', 'Hero image')
        );

        // something a bit more complex -- linking to another page in the site
        $f->addFieldToTab(
            'Root.Main',
            TreeDropdownField::create(  // use a TreeDropdownField to pick a page
                'CallToActionPageID',   // gotta add 'ID' to the field name for TreeDropdownFields! watch out!
                'Call to action page',  // just a label
                'Page'                  // we can filter by page types or just put 'SiteTree' to allow anything
            )
        );

        // we're done! pass the updated field to the cms
        return $f; 
    }

    // if you're adding/editing fields inside a DataExtension instead of a Page (for eg in a CustomSiteConfig)
    // it's a tiny bit different. you still use $db and $has_one exactly the same, but you don't use getCmsFields.
    // Instead...
    public function updateCMSFields(FieldList $fields) {
        // $fields = parent::updateCMSFields()  <-- we don't need to do this! 
      
        $fields->addFieldToTab(...);
      
        // return $fields <-- we don't need to do this either
    }
  
}