368 lines
14 KiB
PHP
368 lines
14 KiB
PHP
<?php
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/**
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* @file
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* Functions implementing Field API multilingual support.
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*/
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use Drupal\Core\Language\Language;
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use Drupal\Core\Entity\EntityInterface;
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use Drupal\field\FieldInterface;
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/**
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* @defgroup field_language Field Language API
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* @{
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* Handles multilingual fields.
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*
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* Fields natively implement multilingual support, and all fields use the
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* following structure:
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* @code
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* $entity->{$field_name}[$langcode][$delta][$column_name]
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* @endcode
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* Every field can hold a single or multiple value for each language code
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* belonging to the available language codes set:
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* - For untranslatable fields this set only contains Language::LANGCODE_NOT_SPECIFIED.
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* - For translatable fields this set can contain any language code. By default
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* it is the list returned by field_content_languages(), which contains all
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* installed languages with the addition of Language::LANGCODE_NOT_SPECIFIED. This
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* default can be altered by modules implementing
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* hook_field_available_languages_alter().
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*
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* The available language codes for a particular field are returned by
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* field_available_languages(). Whether a field is translatable is determined by
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* calling field_is_translatable(), which checks the $field['translatable']
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* property returned by field_info_field() and whether the entity type the field
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* is attached to supports translation.
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*
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* By default, field_invoke_method() processes a field in all available
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* languages, unless it is given a language code suggestion. Based on that
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* suggestion, _field_language_suggestion() determines the languages to act on.
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*
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* Most field_attach_*() functions act on all available language codes, except
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* for the following:
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* - field_attach_form() only takes a single language code, specifying which
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* language the field values will be submitted in.
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* - field_attach_view() requires the language the entity will be displayed in.
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* Since it is unknown whether a field translation exists for the requested
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* language, the translation handler is responsible for performing one of the
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* following actions:
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* - Ignore missing translations, i.e. do not show any field values for the
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* requested language. For example, see field_field_language_alter().
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* - Provide a value in a different language as fallback. By default, the
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* fallback logic is applied separately to each field to ensure that there
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* is a value for each field to display.
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* The field language fallback logic relies on the global language fallback
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* configuration. Therefore, the displayed field values can be in the
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* requested language, but may be different if no values for the requested
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* language are available. The default language fallback rules inspect all the
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* enabled languages ordered by their weight. This behavior can be altered or
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* even disabled by modules implementing hook_field_language_alter(), making
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* it possible to choose the first approach. The display language for each
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* field is returned by field_language().
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*
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* See @link field Field API @endlink for information about the other parts of
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* the Field API.
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*/
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/**
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* Applies language fallback rules to the fields attached to the given entity.
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*
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* Core language fallback rules simply check if fields have a field translation
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* for the requested language code. If so, the requested language is returned,
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* otherwise all the fallback candidates are inspected to see if there is a
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* field translation available in another language.
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* By default this is called by field_field_language_alter(), but this
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* behavior can be disabled by setting the 'field.settings.language_fallback'
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* variable to FALSE.
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*
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* @param $field_langcodes
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* A reference to an array of language codes keyed by field name.
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* @param \Drupal\Core\Entity\EntityInterface $entity
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* The entity to be displayed.
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* @param $langcode
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* The language code $entity has to be displayed in.
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*/
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function field_language_fallback(&$field_langcodes, EntityInterface $entity, $langcode) {
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// Lazily init fallback candidates to avoid unnecessary calls.
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$fallback_candidates = NULL;
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foreach ($field_langcodes as $field_name => $field_langcode) {
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// If the requested language is defined for the current field use it,
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// otherwise search for a fallback value among the fallback candidates.
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if (_field_translated_value_exists($entity, $langcode, $field_name)) {
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$field_langcodes[$field_name] = $langcode;
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}
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else {
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if (!isset($fallback_candidates)) {
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require_once DRUPAL_ROOT . '/core/includes/language.inc';
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$fallback_candidates = language_fallback_get_candidates();
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}
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foreach ($fallback_candidates as $fallback_langcode) {
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if (_field_translated_value_exists($entity, $fallback_langcode, $field_name)) {
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$field_langcodes[$field_name] = $fallback_langcode;
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break;
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}
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}
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}
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}
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}
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/**
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* Collects the available language codes for the given entity type and field.
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*
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* If the given field has language support enabled, an array of available
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* language codes will be returned, otherwise only Language::LANGCODE_NOT_SPECIFIED will
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* be returned. Since the default value for a 'translatable' entity property is
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* FALSE, we ensure that only entities that are able to handle translations
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* actually get translatable fields.
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*
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* @param $entity_type
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* The type of the entity the field is attached to, e.g. 'node' or 'user'.
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* @param $field
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* A field structure.
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*
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* @return
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* An array of valid language codes.
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*/
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function field_available_languages($entity_type, FieldInterface $field) {
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static $drupal_static_fast;
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if (!isset($drupal_static_fast)) {
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$drupal_static_fast['field_langcodes'] = &drupal_static(__FUNCTION__);
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}
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$field_langcodes = &$drupal_static_fast['field_langcodes'];
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$field_name = $field->getFieldName();
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if (!isset($field_langcodes[$entity_type][$field_name])) {
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// If the field has language support enabled we retrieve an (alterable) list
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// of enabled languages, otherwise we return just Language::LANGCODE_NOT_SPECIFIED.
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if (field_is_translatable($entity_type, $field)) {
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$langcodes = field_content_languages();
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// Let other modules alter the available languages.
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$context = array('entity_type' => $entity_type, 'field' => $field);
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drupal_alter('field_available_languages', $langcodes, $context);
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$field_langcodes[$entity_type][$field_name] = $langcodes;
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}
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else {
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$field_langcodes[$entity_type][$field_name] = array(Language::LANGCODE_NOT_SPECIFIED);
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}
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}
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return $field_langcodes[$entity_type][$field_name];
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}
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/**
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* Process the language code suggestion based on the available language codes.
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*
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* If a non-empty language code suggestion is provided it must appear among the
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* available language codes, otherwise it will be ignored.
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*
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* @param $available_langcodes
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* An array of valid language codes.
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* @param $langcode_suggestion
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* A language code or an array of language codes keyed by field name.
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* @param $field_name
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* The name of the field being processed.
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*
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* @return
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* An array of valid language codes.
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*/
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function _field_language_suggestion($available_langcodes, $langcode_suggestion, $field_name) {
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// Handle possible language suggestions.
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if (!empty($langcode_suggestion)) {
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// We might have an array of language suggestions keyed by field name.
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if (is_array($langcode_suggestion) && isset($langcode_suggestion[$field_name])) {
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$langcode_suggestion = $langcode_suggestion[$field_name];
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}
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// If we have a single language code suggestion and it is available, we just
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// return it.
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if (in_array($langcode_suggestion, $available_langcodes)) {
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$available_langcodes = array($langcode_suggestion);
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}
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}
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return $available_langcodes;
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}
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/**
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* Returns available content language codes.
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*
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* @return
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* An array of language codes.
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*/
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function field_content_languages() {
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return array_keys(language_list(Language::STATE_ALL));
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}
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/**
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* Checks whether field language fallback is enabled.
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*/
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function field_language_fallback_enabled() {
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return language_multilingual() && \Drupal::config('field.settings')->get('language_fallback');
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}
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/**
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* Checks whether a field has language support.
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*
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* A field has language support enabled if its 'translatable' property is set to
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* TRUE, and its entity type has at least one translation handler registered.
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*
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* @param $entity_type
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* The type of the entity the field is attached to.
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* @param $field
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* A field data structure.
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*
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* @return
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* TRUE if the field can be translated.
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*/
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function field_is_translatable($entity_type, FieldInterface $field) {
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return $field->isFieldTranslatable() && field_has_translation_handler($entity_type);
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}
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/**
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* Checks if a module is registered as a translation handler for a given entity.
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*
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* If no handler is passed, the function simply checks if there is any
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* translation handler enabled for the given entity type.
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*
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* @param $entity_type
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* The type of the entity whose fields are to be translated.
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* @param $handler
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* (optional) The name of the handler to be checked. Defaults to NULL.
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*
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* @return
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* TRUE, if the given handler is allowed to manage field translations. If no
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* handler is passed, TRUE means there is at least one registered translation
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* handler.
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*
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* @todo Remove this once the migration to the Entity Field API is complete.
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*/
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function field_has_translation_handler($entity_type, $handler = NULL) {
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$info = entity_get_info($entity_type);
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return !empty($info['translatable']);
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}
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/**
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* Ensures that a given language code is valid.
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*
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* Checks whether the given language code is one of the enabled language codes.
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* Otherwise, it returns the current, global language code; or the site's
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* default language code, if the additional parameter $default is TRUE.
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*
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* @param $langcode
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* The language code to validate.
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* @param $default
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* Whether to return the default language code or the current language code in
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* case $langcode is invalid.
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*
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* @return
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* A valid language code.
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*/
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function field_valid_language($langcode, $default = TRUE) {
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$languages = field_content_languages();
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if (in_array($langcode, $languages)) {
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return $langcode;
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}
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return $default ? language_default()->id : language(Language::TYPE_CONTENT)->id;
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}
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/**
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* Returns the display language code for the fields attached to the given
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* entity.
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*
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* The actual language code for each given field is determined based on the
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* requested language code and the actual data available in the fields
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* themselves.
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* If there is no registered translation handler for the given entity type, the
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* display language code to be used is just Language::LANGCODE_NOT_SPECIFIED, as no other
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* language code is allowed by field_available_languages().
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*
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* If translation handlers are found, we let modules provide alternative display
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* language codes for fields not having the requested language code available.
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* Core language fallback rules are provided by field_language_fallback()
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* which is called by field_field_language_alter().
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*
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* @param \Drupal\Core\Entity\EntityInterface $entity
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* The entity to be displayed.
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* @param $field_name
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* (optional) The name of the field to be displayed. Defaults to NULL. If
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* no value is specified, the display language codes for every field attached
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* to the given entity will be returned.
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* @param $langcode
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* (optional) The language code $entity has to be displayed in. Defaults to
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* NULL. If no value is given the current language will be used.
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*
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* @return
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* A language code if a field name is specified, an array of language codes
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* keyed by field name otherwise.
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*/
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function field_language(EntityInterface $entity, $displayed_field_name = NULL, $langcode = NULL) {
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$display_langcodes = &drupal_static(__FUNCTION__, array());
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$id = $entity->id();
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$bundle = $entity->bundle();
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$entity_type = $entity->entityType();
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$langcode = field_valid_language($langcode, FALSE);
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if (!isset($display_langcodes[$entity_type][$id][$langcode])) {
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$display_langcode = array();
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// By default, display language is set to one of the locked languages
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// if the field translation is not available. It is up to translation
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// handlers to implement language fallback rules.
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foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
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if (_field_translated_value_exists($entity, $langcode, $field_name)) {
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$display_langcode[$field_name] = $langcode;
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}
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else {
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// If the field has a value for one of the locked languages, then use
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// that language for display. If not, the default one will be
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// Language::LANGCODE_NOT_SPECIFIED.
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$display_langcode[$field_name] = Language::LANGCODE_NOT_SPECIFIED;
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foreach (language_list(Language::STATE_LOCKED) as $language_locked) {
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if (isset($entity->{$field_name}[$language_locked->id])) {
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$display_langcode[$field_name] = $language_locked->id;
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break;
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}
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}
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}
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}
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if (field_has_translation_handler($entity_type)) {
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$context = array(
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'entity' => $entity,
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'langcode' => $langcode,
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);
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// Do not apply core language fallback rules if they are disabled or if
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// the entity does not have a translation handler registered.
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if (field_language_fallback_enabled() && field_has_translation_handler($entity_type)) {
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field_language_fallback($display_langcode, $context['entity'], $context['langcode']);
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}
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drupal_alter('field_language', $display_langcode, $context);
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}
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$display_langcodes[$entity_type][$id][$langcode] = $display_langcode;
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}
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$display_langcode = $display_langcodes[$entity_type][$id][$langcode];
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// Single-field mode.
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if (isset($displayed_field_name)) {
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return isset($display_langcode[$displayed_field_name]) ? $display_langcode[$displayed_field_name] : FALSE;
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}
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return $display_langcode;
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}
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/**
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* Returns TRUE if a non-empty value exists for a given entity/language/field.
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*/
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function _field_translated_value_exists(EntityInterface $entity, $langcode, $field_name) {
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if (!$entity->hasTranslation($langcode)) {
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return FALSE;
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}
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$field = $entity->getTranslation($langcode)->$field_name;
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$field->filterEmptyValues();
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$value = $field->getValue();
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return !empty($value);
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}
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