SelectBoxEditor wit Data Source

I´m trying to integrate a Select Box Editor, that is filled by a custom data source, like described in the docs. Everything is working well, except that the Select Box is not set to the selected value on page reload.

I forget something?

      type: string
        label: 'Project'
          group: 'settings'
          editor: 'Content/Inspector/Editors/SelectBoxEditor'
            placeholder: 'Bitte auswählen'
            dataSourceIdentifier: 'my-project-datasource'

Mostlikely your array is not in the right format. In needs a label + value section. See the snippet below.

    $options = [];

    foreach ($icons as $key => $value) {
        $options[$key] = [
            'label' => ucfirst(str_replace(['fa-', '-'], ['', ' '], $value)),
            'value' => $value

    return $options; states:

Data sources can be used for various purposes, however the return format is restricted to JSON. An example of their usage is as a data provider for the inspector SelectBoxEditor (see Property Type: string / array SelectBoxEditor – Dropdown Select Editor for details).


I’ve got a similar problem, but even more mad:
One can assign a value to the attached property of the page using the selectBoxEditor.
In my case the value is an identifier for my “project domain model”.
The plugins I wrote, which are using this value work just fine.
The first option of the selectBox is empty (“Please chose …”).
If one chose the page with the SelectBox in the tree, in about 30% - 40% of the cases the SelectBox displays the correct value. The rest ist “please chose”.
Any hints for me?

Thanks in advance