I've ran into an issue with DataObjects which is giving me some behaviour I didn't expect.

So I have something called MailingList which adds a tab in the CMS and allows users to add in contact information which is then displayed in the template for that page.

It has just 2 input fields, email address and description. That's all that needs to be displayed.

It was working how I wanted it to when I was only using it in one place, but during the course of development I've started to add it to other page types and as a result it's now displaying things from the other page types along with the original email and description fields.

Is there a way to stop the DataObject from outputting something from everything it's connected to and just leave it displaying the fields I need?

Easily done, add this in either individual subclasses, or at a certain point to ensure all it's children have it removed.

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

	$fields->removeByName(array('FieldName','RelationshipOrTabName'));

	return $fields;
}

Hmm that doesn't seem to work...

class MailingList extends DataObject {

    private static $db = array(
        'Title' => 'Varchar(25)',
        'Description' => 'Varchar(55)'
    );

    private static $has_one = array(
        'Shows' => 'Shows',
        'Department' => 'Department'
    );

    public function getCMSFields(){

        $fields = parent::getCMSFields();

        $fields->removeByName('Shows'); # Doesn't remove shows, see screenshot

        return $fields;
    }
}

Edit
Just some more info, the Shows and Department have nothing to do with each other which is why I want to remove them, it's just that MailingList DataObject is used in both the page types.

super choice! - yes for that case you'll find the name of the field is actually "ShowsID" - all has_ones have "ID" added to the end

Fantastic! That worked :)

I was concerned that removeByName() would've just hidden the fields but still sent the info on submit but I checked the MailingList table and the ID of the page-type not being used is stored as 0 (Phew!)

Thanks for letting me know, I'll bare that in mind moving forward.