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DataObjectManager Module /

Discuss the DataObjectManager module, and the related ImageGallery module.

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ManyManyDataObjectManager - Unable to Use Function Call $field_names Array?

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Community Member, 245 Posts

12 July 2012 at 5:49am

Edited: 12/07/2012 5:52am


I've been working with the DataObjectManager module for years, but today I came across a strange error (probably a mistake in my code that i can't see). I have a ManyManyDataObjectManager in my generic Page class like so:


class Page extends SiteTree {

	static $many_many = array(
		"Buttons" => "Button"
	function getCMSFields() {
		$fields = parent::getCMSFields();
		$buttons = new ManyManyDataObjectManager(
			"Buttons", // relation name
			"Button", // object class
			Button::$field_names, // fields to show in table
			Button::getCMSFields_forPopup(), // form that pops up for edit
			"", // a filter to only display item associated with this page
			"SortOrder ASC" // Sort
		$fields->addFieldToTab("Root.Content.Buttons", $buttons);
		return $fields;


And here is my Button DataObject:

class Button extends DataObject {
	static $db = array(
		"Title" => "Text"
   	static $has_one = array(
    	        "LinkedPage" => "SiteTree"
	static $belongs_many_many = array(
		"Pages" => "Page"
	static $field_names = array(
		"Title" => "Title",
		"PageName" => "Page Name"
   	function getCMSFields_forPopup() {

		$fields = new FieldSet();
		$fields->push(new TextField("Title", "Text"));
		$LinkedPageField = new SimpleTreeDropdownField("LinkedPageID", "Link to Page", "SiteTree");
		$LinkedPageField->setEmptyString("-- None --");

		return $fields;


	public function PageName() {
		$PageObject = DataObject::get_by_id("SiteTree", $this->LinkedPageID);
		return ($PageObject!=null) ? $PageObject->Title : "";

The error when I click on a page in the CMS is:

Unknown column 'PageName' in 'field list'

Ha? I thought I could put function names in this associative array. It isn't meaningful to put the LinkedPageID itself in the display table, which is why I am calling PageName() instead. Indeed, I can't use LinkedPageID here either or I get this error:

Duplicate column name 'LinkedPageID'

What am I doing wrong here?

Thanks in advance,