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General questions about getting started with SilverStripe that don't fit in any of the categories above.

Moderators: martimiz, Sean, Ed, biapar, Willr, Ingo, swaiba

Getting id's from a many to many relation

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2 Posts   1508 Views


Community Member, 20 Posts

10 September 2009 at 7:41am

Hello guys,

Need a little help getting some IDs from a relation table.

The below code is what i use for a home page. In the administration you can now select multible pages, and the IDs are saved to the relation table "ForsidePage_PreviewList".
i need to use the IDs from this table in my filter in "ForsidePage_Controller" in the function "showPreviews", and not the hardcoded ...".ID IN (8,9,10)" ...

How can this be done?

class ForsidePage extends Page {
static $db = array();

static $has_one = array();

public static $many_many = array(
'PreviewList' => 'SiteTree'

function getCMSFields() {
$fields = parent::getCMSFields();
$fields->addFieldToTab('Root.Content.Previews', new TreeMultiselectField( 'PreviewList', 'Preview Sites', 'SiteTree'));

return $fields;

class ForsidePage_Controller extends Page_Controller {
function showPreviews() {
$myIds = "";// Query to get IDs from the relation table
$records = DataObject::get("WithPreviewPage", "`WithPreviewPage`.ID IN (8,9,10)");
return ($records);



Forum Moderator, 922 Posts

11 September 2009 at 12:19am

Edited: 11/09/2009 12:21am

What you're looking for is a method on the relational getter called getIdList(). To get an array of the IDs of the relation, simply call that method like so (on your controller):


Then you can just implode the array into a comma separated ID string ready for your SQL query.