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Moderators: martimiz, Sean, biapar, Willr, Ingo, simon_w

$has_one / $has_many and getCMSFields


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6 Posts   3748 Views

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julian

Community Member, 17 Posts

7 March 2007 at 11:10am

Edited: 10/03/2007 1:24pm

Hi guys,

ok so I've set up these relationships: "A Museum can have many Exhibitions". I want to link Exhibitions to Museums in the admin gui but I'm a little lost?

Exhibition.php:

class Exhibition extends Page {
...
static $has_one = array(
...
'Museum' => 'Museum'
);

Then in Museum.php:

class Museum extends Page {
...
static $has_many = array(
   'Exhibitions' => 'Exhibition'
);
}

... any ideas what magic I have to do to change getCMSFields so that under an Exhibition I get a dropdown to choose which Museum it belongs to, and under a Museum it lists / enables changing of Exhibitions?

Yes I could make Exhibitions children of Museums but there are reasons why I don't want to do this, and besides, it wouldn't work for many_many -- and so I have a similar question for that..

It looks like RelatedDataEditor is the way to do this but when I tried this it crashed because it enforced 1..* not 0..* ?

thanks very much!

Julian (Kiwi in Wimbledon)

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julian

Community Member, 17 Posts

8 March 2007 at 9:26pm

hello... anyone out there? It looks like the entire silverstripe community has gone on holiday? looking forward to any guidance you can help with... thanks!

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Ingo

Forum Moderator, 801 Posts

9 March 2007 at 12:40am

Edited: 09/03/2007 12:41am

function getCMSFields() {
$fields = parent::getCMSFields();
$fields->addFieldToTab('Root.Main',new DropdownField('MuseumID','Museum'));
return $fields;
}

Thats the simplest solution for a has_one. If your relation is SiteTree-based (rather than extending DataObject), have a look at TreeDropdownField (or TreeMultiSelectField for has_many).
TableListField, TableField and ComplexTableField basically do the same thing as RelatedDataEditor for has_many-Relationsships. They are very versatile ways to display relationship, unfortunately quite poorly documented ;)

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julian

Community Member, 17 Posts

9 March 2007 at 10:14am

Thanks Ingo! That whole 'MuseumID' thing... where can I find out more about this? I'm always keen to read docs / code etc so I don't pester you guys but I did get a little stuck on this to be honest...

thanks!
J

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Ingo

Forum Moderator, 801 Posts

9 March 2007 at 12:07pm

Edited: 09/03/2007 12:11pm

We've got a very brief documentation on http://doc.silverstripe.com/doku.php?id=datamodel.

We're using Object Relational Mapping (http://en.wikipedia.org/wiki/Object-relational_mapping) and basically the same conventions as Ruby on Rails to build automatic database-relations. Hence, when you write something like
static $has_one = array("Museum"=>"Museum");
our db-builder adds a MuseumID-column to the table.

I forgot an important chunk of code that possibly confused you:
function getCMSFields() {
   $fields = parent::getCMSFields();
   $fields->addFieldToTab(
      'Root.Main',
      new DropdownField(
         'MuseumID',
         'Museum',
         DataObject::get('Museum')->toDropDownMap()
      )
   );
   return $fields;
}
This adds an actual value-map to the dropdown (see DataObjectSet for more info on this).

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julian

Community Member, 17 Posts

14 March 2007 at 11:35am

ok I'll update the wiki at some stage, but just for the sake of preventing others spend their entire saturdays on this, this is how $has_many works. I wanted Artworks to be favourited by users. So this is what I did:

class Artwork extends SiteTree {
...
   static $many_many = array (
      'MemberFavourites' => 'Member'
   );
...

   /** Used for the admin GUI to enable users to create content */
   function getCMSFields() {
      ...
      $this->populateMemberFavourites( $fields );
      ...
      return $fields;
   }
}

         // Some explanation of the Checkbox as it's not clear from dox.
         // 'MemberFavourites' -- this should be the name of the property you want the checkbox field to update when you change. Get this wrong and your values won't be saved.
         // $idList -- this should be the list of the values that have been chosen. Get this wrong and the values won't reflect the database when they're created.
         // NOTE that 'toDropDownMap()' is nothing special -- it's a map designed for dropdown lists but equally works well for checkbox lists etc.

   /** create a GUI for showing those members who chose this item as a favourite */
   function populateMemberFavourites( $pFields ) {
      $components = $this->getManyManyComponents('MemberFavourites');
      $idList = $components->getIdList();
      
      $dataSet = DataObject::get('Member');
      if( $dataSet ) {
         $theCheckboxFieldSet = new CheckboxSetField('MemberFavourites','Members who marked this artwork as a fave',$dataSet->toDropDownMap(), $idList);
         $pFields->addFieldToTab( 'Root.Content.MemberFavourites', $theCheckboxFieldSet );
      }
   }