I have a settings form that saves site wide configuration information My submit form function looks something like this

$data = [];
foreach ($groups as $key) {
  $data[$key] = $form_state->getValue($key);
  if (empty($data[$key])) {
    $data[$key] = [];


My issue is that in a callback I'd like to be able to directly set the value of a single configuration field that is nested in that data array without grabbing everything again and changing the data array and resetting it with ->setData

The data in my config array looks like this

    'num_campaigns'=> 4
    'campaigns'=> [
        'campaign_ids' => ['abc','def','ghi','jkl']

And my callback looks like this

  public function removeField(array $form, FormStateInterface $form_state){
    $config = $this->getConfig();
    $num_campaigns = $config['num_campaigns']-1;
    $config_factory = $this->configFactory->getEditable('my_config.settings');
    $config_factory->set('num_campaigns', $num_campaigns);
    $config_factory->set(['campaigns','campaign_ids',$num_campaigns], '')

My issue is that the set method accepts a string and not an array. If I can only supply a string how do I set the value of something that is nested down in my config array? Is using set even an option? Or do I have to resort to using setData?

1 Answer 1


The first parameter is a string with nested keys separated by dots. The second parameter is the value, which is not necessarily a string. It can also be an array:

$config->set('campaigns.campaign_ids', ['abc','def','ghi','jkl']);
  • That worked thanks!
    – Amy
    May 24, 2022 at 16:08

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