Block configuration form values are not translated

Question

I have the following code in my custom block:

    public function blockForm($form, FormStateInterface $form_state) {
    $form = parent::blockForm($form, $form_state);

    $config = $this->getConfiguration();

    $form['headline'] = array(
      '#type' => 'textfield',
      '#title' => $this->t('Block headline'),
      '#default_value' => isset($config['headline']) ? $config['headline'] : NULL,
      '#required' => TRUE,
    );


      return $form;
    }

and:

    public function blockSubmit($form, FormStateInterface $form_state) {
      $this->setConfigurationValue('headline', $form_state->getValue('headline'));
    }

The configuration is saved correctly, but only for English language.
The block translation doesn't show my variable (headline) in the translatable configuration.
What am I doing wrong?

Thanks

Answer 1

You have to provide a schema in /config/schema/mymodule.schema.yml of the type block_settings.

Example:

block.settings.example_configurable_text:
  type: block_settings
  label: 'Example configurable text block configuration'
  mapping:
    block_example_string:
      type: text
      label: 'Block contents'

From the example module https://git.drupalcode.org/project/examples/-/blob/HEAD/modules/block_example/config/schema/block_example.schema.yml

Configurations mapped as type: label (single line of text) or type: text (multiple lines of text) are translatable.