302 lines
11 KiB
PHP
302 lines
11 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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/**
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* @defgroup field_language Field Language API
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* @{
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* Handling of 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 belonging
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* to the available languages set:
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* - For untranslatable fields this set only contains LANGUAGE_NONE.
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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_NONE. This default can be
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* altered by modules implementing hook_field_available_languages_alter().
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*
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* The available languages 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 there is at least one
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* translation handler available for the field. A translation handler is a
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* module registering itself via hook_entity_info() to handle field
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* translations.
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*
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* By default, _field_invoke() and _field_invoke_multiple() are processing a
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* field in all available languages, unless they are given a language
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* suggestion. Based on that suggestion, _field_language_suggestion() determines
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* the languages to act on.
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*
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* Most field_attach_*() functions act on all available languages, except for
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* 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 locale_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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* Implements hook_multilingual_settings_changed().
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*/
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function field_multilingual_settings_changed() {
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field_info_cache_clear();
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}
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/**
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* Collects the available languages 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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* languages will be returned, otherwise only LANGUAGE_NONE will be returned.
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* Since the default value for a 'translatable' entity property is FALSE, we
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* ensure that only entities that are able to handle translations actually get
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* 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, $field) {
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static $drupal_static_fast;
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if (!isset($drupal_static_fast)) {
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$drupal_static_fast['field_languages'] = &drupal_static(__FUNCTION__);
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}
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$field_languages = &$drupal_static_fast['field_languages'];
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$field_name = $field['field_name'];
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if (!isset($field_languages[$entity_type][$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_NONE.
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if (field_is_translatable($entity_type, $field)) {
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$languages = 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', $languages, $context);
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$field_languages[$entity_type][$field_name] = $languages;
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}
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else {
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$field_languages[$entity_type][$field_name] = array(LANGUAGE_NONE);
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}
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}
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return $field_languages[$entity_type][$field_name];
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}
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/**
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* Process the given language suggestion based on the available languages.
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*
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* If a non-empty language suggestion is provided it must appear among the
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* available languages, otherwise it will be ignored.
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*
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* @param $available_languages
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* An array of valid language codes.
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* @param $language_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_languages, $language_suggestion, $field_name) {
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// Handle possible language suggestions.
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if (!empty($language_suggestion)) {
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// We might have an array of language suggestions keyed by field name.
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if (is_array($language_suggestion) && isset($language_suggestion[$field_name])) {
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$language_suggestion = $language_suggestion[$field_name];
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}
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// If we have a language suggestion and the suggested language is available,
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// we return only it.
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if (in_array($language_suggestion, $available_languages)) {
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$available_languages = array($language_suggestion);
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}
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}
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return $available_languages;
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}
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/**
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* Returns available content languages.
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*
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* The languages that may be associated to fields include LANGUAGE_NONE.
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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() + array(LANGUAGE_NONE => NULL));
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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, $field) {
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return $field['translatable'] && field_has_translation_handler($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, simply check if there is any translation handler
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* 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 $handler
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* (optional) The name of the handler to be checked. Defaults to NULL.
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*
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* @return
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* TRUE, if the given handler is allowed to manage field translations. If no
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* handler is passed, TRUE means there is at least one registered translation
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* handler.
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*/
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function field_has_translation_handler($entity_type, $handler = NULL) {
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$entity_info = entity_get_info($entity_type);
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if (isset($handler)) {
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return !empty($entity_info['translation'][$handler]);
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}
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elseif (isset($entity_info['translation'])) {
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foreach ($entity_info['translation'] as $handler_info) {
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// The translation handler must use a non-empty data structure.
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if (!empty($handler_info)) {
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return TRUE;
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}
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}
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}
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return FALSE;
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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 is one of the enabled languages. Otherwise,
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* it returns the current, global language; or the site's default language, if
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* 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 $langcode is invalid.
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* @return
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* A valid language code.
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*/
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function field_valid_language($langcode, $default = TRUE) {
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$enabled_languages = field_content_languages();
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if (in_array($langcode, $enabled_languages)) {
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return $langcode;
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}
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global $language_content;
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return $default ? language_default('language') : $language_content->language;
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}
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/**
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* Returns the display language for the fields attached to the given entity.
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*
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* The actual language for each given field is determined based on the requested
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* language and the actual data available in the fields themselves.
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* If there is no registered translation handler for the given entity type, the
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* display language to be used is just LANGUAGE_NONE, as no other language code
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* is allowed by field_available_languages().
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* If translation handlers are found, we let modules provide alternative display
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* languages for fields not having the requested language available.
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* Core language fallback rules are provided by locale_field_language_fallback()
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* which is called by locale_field_language_alter().
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*
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* @param $entity_type
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* The type of $entity.
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* @param $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 languages for every field attached to
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* the given entity will be returned.
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* @param $langcode
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* (optional) The language code $entity has to be displayed in. Defaults to
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* NULL. If no value is given the current language will be used.
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*
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* @return
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* A language code if a field name is specified, an array of language codes
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* keyed by field name otherwise.
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*/
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function field_language($entity_type, $entity, $field_name = NULL, $langcode = NULL) {
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$display_languages = &drupal_static(__FUNCTION__, array());
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list($id, , $bundle) = entity_extract_ids($entity_type, $entity);
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$langcode = field_valid_language($langcode, FALSE);
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if (!isset($display_languages[$entity_type][$id][$langcode])) {
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$display_language = array();
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// By default display language is set to LANGUAGE_NONE if the field
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// translation is not available. It is up to translation handlers to
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// implement language fallback rules.
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foreach (field_info_instances($entity_type, $bundle) as $instance) {
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$display_language[$instance['field_name']] = isset($entity->{$instance['field_name']}[$langcode]) ? $langcode : LANGUAGE_NONE;
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}
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if (field_has_translation_handler($entity_type)) {
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$context = array(
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'entity_type' => $entity_type,
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'entity' => $entity,
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'language' => $langcode,
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);
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drupal_alter('field_language', $display_language, $context);
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}
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$display_languages[$entity_type][$id][$langcode] = $display_language;
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}
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$display_language = $display_languages[$entity_type][$id][$langcode];
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// Single-field mode.
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if (isset($field_name)) {
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return isset($display_language[$field_name]) ? $display_language[$field_name] : FALSE;
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}
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return $display_language;
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}
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