SilverStripe - Adding 2 TreeDropdownFields, only one works

Question

I've run into a very bizarre issue while creating 2 TreeDropdownFields for a DataObject. For some reason, only 1 of the 2 TreeDropdownFields render correctly in the SilverStripe admin. The other doesn't render as a TreeDropdownField at all but just as a label:

Here is the code:

class HomeBanner extends DataObject {

    public static $db = array(
        'SortOrder' => 'Int',
        'Title' => 'Varchar'
    );

    public static $has_one = array(
        'Image' => 'Image',
        'SecondaryImage' => 'Image',
        'FirstLink' => 'SiteTree',
        'SecondLink' => 'SiteTree'
    );

    public function getCMSFields() {
        $fields = parent::getCMSFields();
        $fields->removeFieldFromTab('Root.Main', 'PageID');
        $fields->removeFieldFromTab('Root.Main', 'SortOrder');

        $fields->addFieldToTab('Root.Main', new TreeDropdownField('FirstLinkID', 'First Link', 'SiteTree'));
        $fields->addFieldToTab('Root.Main', new TreeDropdownField('SecondLinkID', 'Second Link', 'SiteTree'));

        return $fields;
    }

    public static $summary_fields = array(
        'ID' => 'ID',
        'Title' => 'Title',
        'Thumbnail' => 'Thumbnail'
    );

    public function getThumbnail() {
        return $this->Image()->CMSThumbnail();
    }
}

Here is what I have tried so far:

running dev/build/?flush=true
running ?flush=all and ?flush=1
logging out and logging back in after the dev/build + flushes
logging into the admin in another browser (I typically use Chrome but logged into the site's admin on FireFox and saw the same problem)
The error logs report nothing -- they're clear
There are no errors in the console for Chrome's dev tools
Adding a third TreeDropdownField will allow the first 2 to render properly but the third one will just show a label instead of a TreeDropdownField
This format works, but doesn't save whatever is selected--it clears your choice as soon as you leave the page. Also, it deletes all that was saved already in the admin unless I remove it. I can't make changes or else the items saved get removed.):

$fields->addFieldToTab('Root.Main', new TreeDropdownField('SecondLink', 'Second Link', 'SiteTree', 'ID'));

Does anyone have any ideas as to why this could be happening? It doesn't seem to make sense that you can't have multiple TreeDropdownFields.

The name “HomeBanner” suggests to me that there should also be a has_one pointing back to HomePage or similar? The cause of this is probably that SilverStripe is automatically trying to set one of the has_one relations to point back to the page that the banner belongs to. — kinglozzer
Crap...that is actually what I was missing. I can't believe I didn't realize it before! I think it's because I've been out of SilverStripe for a couple months and forgot some things. Thanks! — Dejsa Cocan

kinglozzer kinglozzer · Accepted Answer · 2017-03-30T16:14:30

Reposting as this turned out to be the answer:

The name “HomeBanner” suggests to me that there should also be a has_one pointing back to HomePage or similar? The cause of this is probably that SilverStripe is automatically trying to set one of the has_one relations to point back to the page that the banner belongs to.

Similar conflicts can also happen when using code like this:

class Page extends SiteTree {
    private static $has_many = [
        'Banners' => 'Banner'
    ];
}

class Banner extends DataObject {
    private static $has_one = [
        'Page' => 'Page',
        'LinkedPage' => 'Page'
    ];
}

As SilverStripe doesn't know whether it should use PageID or LinkedPageID to auto-populate that side of the has_many relation (GridField will try to automatically assign the correct has_one ID).

In these cases, you can use dot-notation to distinguish between them - you’d change it to $has_many = ['Banners' => 'Banner.Page'];. See https://docs.silverstripe.org/en/3/developer_guides/model/relations/#has-many for more info.

SilverStripe - Adding 2 TreeDropdownFields, only one works

1 Answers