SilverStripe 3ブール型読み取り専用フィールド

Question

Boolean変数は、->Nice()関数の値（Yes/No）を示す読み取り専用フィールドとしてgetCMSFields()に表示するにはどうすればよいですか？ここで

は、私が試したものです：

class EventMember extends Member { 

    static $db = array (
     'NewsLetter' => 'Boolean' 
    ); 

    public function getCMSFields() { 
     $fields = parent::getCMSFields(); 


     //WHAT I TRIED 

     //$fields->fieldByName('NewsLetter')->performReadonlyTransformation(); 
     /*$newsletter = new ReadonlyField('NewsLetter', 'NewsLetter'); 
     $value = $newsletter->getValue(); 
     $newsletter->setValue($value)->Nice(); 
     $fields->replaceField('NewsLetter', $newsletter);*/ 

     //$fields->addFieldToTab('Root.Main', $nL = CheckboxField::create('NewsLetter', 'Newsletter')); 
     //$value = $this->NewsLetter->Value()->Nice(); 
     //$nL->setValue($value)->Nice(); 


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

} 

Answer 1

$fields->removeByName('NewsLetter'); 
$nL = DBField::create_field('ReadonlyField', $this->obj('NewsLetter')->Nice(), 'Newsletter'); 
$fields->addFieldToTab('Root.Main', $nL);