Impossible to save nodes if translation is newer than default language

Here is a test that shows the error message appearing during execution of ContentTranslationUITest::assertOutdatedStatus().

Rerolled the test. Mind that this is not intended to be the actual test for this bug, it just indicates the error message appearing when translations are marked as outdated.

The way the 'changed' timestamps are updated in the node_field_data table is not consistent. If a node is saved in the original language, the timestamps of all languages are updated. When a translation is saved, only the timestamp of the translation is updated.

1. Create a new node in English. Only the english field data is saved.

mysql> select langcode,changed from node_field_data where nid=12;
+----------+------------+
| langcode | changed    |
+----------+------------+
| en       | 1379312173 |
+----------+------------+

2. Add a translation in Khmer. Only the timestamp of the Khmer translation is updated in node_field_data.

mysql> select langcode,changed from node_field_data where nid=12;
+----------+------------+
| langcode | changed    |
+----------+------------+
| en       | 1379312173 |
| km       | 1379312364 |
+----------+------------+

3. Resave the node in English. This time both the timestamps of the English and Khmer translations are updated again.

mysql> select langcode,changed from node_field_data where nid=12;
+----------+------------+
| langcode | changed    |
+----------+------------+
| en       | 1379312451 |
| km       | 1379312451 |
+----------+------------+

What is the correct one? I suppose only the updated translation should have its timestamp changed, otherwise you wouldn't know when exactly a translation was updated.

From NodeFormController::validate():

    if ($node->id() && (node_last_changed($node->id(), $this->getFormLangcode($form_state)) > $node->getChangedTime())) {
      form_set_error('changed', t('The content on this page has either been modified by another user, or you have already submitted modifications using this form. As a result, your changes cannot be saved.'));
    }

node_last_changed() retrieves the changed timestamp of the current translation, while getChangedTime() gets the one from LANGUAGE_UNDEFINED. So as soon as any translation is more recent than the default language this fails. We should allow to pass a language parameter to getChangedTime().

I also wonder why the constructor of EntityNG only stores the timestamps of the default language version, wouldn't it be more interesting to store these for all translations?

This solves it, passing the langcode to getChangedTime(). If this is deemed a good approach we should extend this to the other properties.

This patch returns the most recent changed timestamp across all translations. I also added getChangedTime() to the NodeInterface as it was missing.

The tests are failing because the $this->values['changed'] array sometimes contains strings, and sometimes arrays :-/

For example if I inspect it in Entity::__construct() when running NodeTranslationTest:

'changed' =>
  array (
    'und' => '1379485053',
    'it' => '1379485152',
  ),

and during CommentActionsTest:

'changed' =>
  array (
    'und' => 
      array (
        0 => 
          array (
            'value' => 1379485611,
          ),
      ),
  )

I'm working on this but I could use some input. In this patch I have addressed the remarks from #13, but I have trouble retrieving the 'changed' timestamp of a particular translation. I assume I should use EntityNG::getTranslatedField() for it but this is always returning the timestamp of the default language, because the 'changed' property is not marked as translatable:

Say I have a node with English as the default language, and a Spanish translation. I want to retrieve the 'changed' timestamp from the Spanish translation, so I call it with $this->getTranslatedField('changed', 'es'):

  protected function getTranslatedField($property_name, $langcode) {
    // ...
    if (!isset($this->fields[$property_name][$langcode])) {
      $definition = $this->getPropertyDefinition($property_name);
      // ...

      // $definition['translatable'] is not set for the 'changed' property, so this evaluates to TRUE:
      if ($langcode != Language::LANGCODE_DEFAULT && empty($definition['translatable'])) {
        // The English timestamp will be retrieved here instead of the Spanish one.
        $this->fields[$property_name][$langcode] = $this->getTranslatedField($property_name, Language::LANGCODE_DEFAULT);
      }
      // ...
    }
    return $this->fields[$property_name][$langcode];
  }

I understand that the 'changed' property is not something which we should 'translate' but it should still be accessible in some way. This also is the case for other properties which are not strictly translatable but are translation-specific.

This problem does not occur any more since #2129039: Integrity constraint violation when translating body field got in. Marking this as a duplicate.