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Create belongs_many_many relation on self


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MarijnKampf

29 July 2010 at 3:31am Community Member, 164 Posts

I've been trying to create a $many_many / $belongs_many_many relation with self. I've come across several use cases for this, e.g. setting groups of related pages so I can add 'See also links' to pages, Properties that can be booked together etc.

I've gotten a [url=http://silverstripe.org/data-model-questions/show/276625#post276625]has_many relation to work[/url] on self, but I would like the relation to be maintained on both ends. That is, if I set the checkbox on Page A that it is related to Page B, the checkbox for Page A should be automatically set for Page B (Just as it would work with other $belongs_many_many relations).

I've tried the code below (based on tutorial 5) where I want to set which modules are related (e.g. i18n and Translatable). My code only maintains the relation in one direction, the other side isn't maintained.

Is there a way of achieving a bi-directional relation?

<?php

class Module extends Page {

   static $db = array(
      'Name' => 'Text'
   );

   static $many_many = array(
      'RelatedModules' => __CLASS__
   );

   static $belongs_many_many = array(
      'Projects' => 'Project',
      'Modules' => __CLASS__
   );

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

      $fields->addFieldToTab( 'Root.Content.Main', new TextField( 'Title', 'Title' ) );

      $tablefield = new ManyManyComplexTableField(
         $this,
         'RelatedModules',
         'Module',
         array(
            'Title' => 'Title',
         ),
         'getCMSFields_forPopup'
      );
      $tablefield->setAddTitle( 'A Module' );

      $fields->addFieldToTab( 'Root.Content.RelatedModules', $tablefield );

      return $fields;
   }

   function getCMSFields_forPopup() {
      $fields = new FieldSet();
      $fields->push( new TextField( 'Name' ) );
      $fields->push( new ManyManyComplexTableField($this, 'RelatedModules', "Module", array('Title' => 'Title')));
      return $fields;
   }
}

?>