"On" and "Off" values for boolean fields are not translatable

This applies to 8.x as well.

IMO, options labels - for radios and checkboxes - should be translated on _options_prepare_options()

The option and label is translated only when selecting "Default translated" instead of "Default" under "Manage Display." However the help text does not show as translated no matter what is chosen. Even if the string has been translated, it shows only the source. At least this is the case in the most recent version of Drupal 7.

I just verified this with the latest 8.0.x. The label and help text are available for translation but the "On" and "Off" labels are not.

Adjusted the title to match the issue in 8.x. That'll need to change if/when this gets tagged for backporting to 7.x.

Turns out the Custom text field is not translatable either.

The attached patch fixes that issue.

However, I wasn't able to get the On/Off values to show on admin/structure/types/manage/article/fields/<node-type>.<field_machine_name>/translate/<language>/edit. I tried adding a @FieldType annotation similar to that for ImageItem, but that only allowed a translation when the content is being edited. I was trying to get it to show like the default value for ImageItem.

Any pointers would be appreciated.

Oh, the above patch also adds a settingsSummary function which is missing for this formatter. Technically out of scope for this issue -- let me know if that needs a new issue instead.

Testbots were having problems and terminating part-way through, according to IRC. Retrying...

I'm working on this in the mentored sprint in the Drupalcon Barcelona. I'll try to apply the patch and submit again the test.

I mentored @mercepedraza during DrupalCon Barcelona. Our discussion concluded that the patch in #4 uses a wrong approach.

+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/BooleanFormatter.php
@@ -102,7 +102,7 @@ public function settingsForm(array $form, FormStateInterface $form_state) {
-      '#default_value' => $this->getSetting('format_custom_false'),
+      '#default_value' => $this->t($this->getSetting('format_custom_false')),

Wrapping a t() around a method call is D7 style of translating a configuration value. As far as I know, we can allow the default configuration to be translated by adding a schema for this form.

This is a partial solution that adds modifies the core data type to make the on- and off-labels translatable.
Some faults that needs to be addressed:

• Saving a translated configuration of the field (e.g. admin/structure/types/manage/article/fields/node.article.field_boolean/translate > edit > save), give the error Notice: Undefined index: field.storage.node.field_boolean in Drupal\config_translation\Form\ConfigTranslationFormBase->submitForm()
• Manage display of a boolean field > configure field > select 'Custom' > Label fields don't have a default.

Todo:

• Check if the right label language is used when editing an entity and when displaying the entity.
• Add tests

A colleague tipped me about this issue:
https://www.drupal.org/node/2609874

Are these duplicate of one another?

@badrange, I think you're right. And, as #11 points out there are better ways to do this, which are being used in the issue you linked to. I'll open a followup for the missing setSummary().

Opened #2671446: The Boolean field formatter does not provide a settings summary to handle the missing settingsSummary.

/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/BooleanFormatter.php

  /**
   * {@inheritdoc}
   */
  public function settingsSummary() {
    $summary = [];
    $setting = $this->getSetting('format');

    if ($setting == 'custom') {
      $summary[] = $this->t('Custom text: @true_label / @false_label', [
        '@true_label' => $this->getSetting('format_custom_true'),
        '@false_label' => $this->getSetting('format_custom_false'),
      ]);
    }
    else {
      $formats = $this->getOutputFormats();
      $summary[] = $this->t('Display: @true_label / @false_label', [
        '@true_label' => $formats[$setting][0],
        '@false_label' => $formats[$setting][1],
      ]);
    }

    return $summary;
  }

change
'@true_label' => t($this->getSetting('format_custom_true')),
'@false_label' => t($this->getSetting('format_custom_false')),

  /**
   * {@inheritdoc}
   */
  public function settingsSummary() {
    $summary = [];
    $setting = $this->getSetting('format');

    if ($setting == 'custom') {
      $summary[] = $this->t('Custom text: @true_label / @false_label', [
        '@true_label' => t($this->getSetting('format_custom_true')),
        '@false_label' => t($this->getSetting('format_custom_false')),
      ]);
    }
    else {
      $formats = $this->getOutputFormats();
      $summary[] = $this->t('Display: @true_label / @false_label', [
        '@true_label' => $formats[$setting][0],
        '@false_label' => $formats[$setting][1],
      ]);
    }

    return $summary;
  }