- Root Language folders
- Babel view
- Language independent fields
- Translation locator policy
- Language selector policy
- The assets folder - a shared “Language Independent Folder”
- Translation map
- Google Translation Service integration
- LinguaPlone migration
- Marking objects as translatables
- Marking fields as language independant
- Internal design of plone.app.multilingual
- Source Code
In the old days before Plone 4.3, talking about multi-language support in Plone is talk about Products.LinguaPlone. It has been the defacto standard for managing translations of Archetypes-based content types in Plone through the years. Somehow its functionality never made its way into the Plone core and today it is in legacy status. Nowadays, Plone faces the rising of Dexterity content types and its adoption into the core since Plone 4.3. With Plone 5 released, the transition is completed and Dexterity is shipped as its default content type story.
plone.app.multilingual was designed originally to provide Plone a whole multilingual story. Using ZCA technologies, enables translations to Dexterity and Archetypes content types as well managed via an unified UI.
This module provides the user interface for managing content translations. It’s the app package of the next generation Plone multilingual engine. It’s designed to work with Dexterity content types and the old fashioned Archetypes based content types as well. It only works with Plone 4.1 and above due to the use of UUIDs for referencing the translations.
After more than 7 years, a GSOC, redesigns, reimplementations due to deprecated libraries, two major Plone versions finally we are able to say that plone.app.multilingual is finally here.
1.x- Plone 4.x with Archetypes and Dexterity
2.x- Plone >= 4.x, < 5.0 with plone.app.contenttypes (Dexterity) and real shared content
3.x- Plone >= 5.x. 3.0.17 will likely be the latest release on this branch. You are encouraged to use 4.x.
4.x- Plone >= 5.x (5.0.3 minimum, due to GenericSetup dependency)
PAM is composed of two packages, one is mandatory:
- plone.app.multilingual (core, UI, enables Dexterity support via a behavior)
and one optional:
- archetypes.multilingual (enables Archetypes support)
To use this package with both Dexterity and Archetypes based content types you should add the following line to your eggs buildout section:
eggs = plone.app.multilingual[archetypes]
To use this package with plone.app.contenttypes you should add the following line to your eggs buildout section:
eggs = plone.app.multilingual
After re-running your buildout and installing the newly available add-ons, you should go to the Languages section of your site’s control panel and select at least two or more languages for your site. You will now be able to create translations of Plone’s default content types, or to link existing content as translations.
These are the most important features PAM provides.
After the setup, PAM will create root folders for each of your site’s languages and put translated content into the appropriate folders. A language folder implements INavigationRoot, so from the user’s point of view, each language is “jailed” inside its correspondent language folder. There are event subscribers in place to capture user interaction with content and update the language in contents accordingly, for example when user moves or copy content between language folders.
An evolution of the LP translate view, unified for either Archetypes and Dexterity content types. It features an already translated content viewer for the current content being edited via an ajaxified dynamic selector that shows them on the fly on user request.
PAM has support for language independent fields, but with a twist respect the LP implementation. As PAM does design does not give more relevance to one translated object above the others siblings (has no canonical object), fields marked as language independent get copied over all the members of the translation group always. The PAM UI will warn you about this behavior by reminding you that the values in the field on the other group participants will be overwritten.
When translating content, this policy decides how it would be placed in the site’s structure. There are two policies in place:
- LP way, the translation gets placed in the nearest translated folder in parent’s hierarchy
- Ask user where to place the translated element in the destination language root folder
While browsing the site, the language selector viewlet allows users to switch site’s content language and ease access between translations of the current content. There are two policies in place in case the translation of a specific language does not exist (yet):
- LP way, the selector shows the nearest translated container.
- Shows the user an informative view that shows the current available translations for the current content.
In order to ease the translation tasks, we devised a tool that displays in a useful way all the current translated objects and its current translation information. The map also shows a list of missing translations in case you want to build a mirrored (completely) translated site.
If you are subscriber of the Google Translation service (a paid service), you can setup your API key on Languages site setup. Then, you will notice a new icon in the babel view that takes the original field on the left side and using Google Translations service, translates its contents and fill the right side field.
You can migrate your existing LP powered sites to PAM using the Migration tab in the Languages control panel. The migration has been divided into 4 steps for separation of concerns and for improving the success of each of the required procedures.
The migration of LinguaPlone content depends on an up-to-date Language index. Use this step to refresh this index. Warning: Depending on the number of items in your site, this can take a considerable amount of time. This step is not destructive and can be executed as many times as needed.
This step will move the site’s content to its correspondent root language folder and previously will make a search for misplaced content through the site’s content tree and will move them to its nearest translated parent. Warning: This step is destructive as it will alter your content tree structure. Make sure you have previously configured your site’s languages properly in the ‘Site Languages’ tab of the ‘Languages’ control panel. It’s advisable that you do not perform this step on production servers having not tried it in development/preproduction servers previously. Depending on the distribution of your site’s content and the accuracy of the language information on each content object you may need to relocate manually some misplaced content after this step. Despite the fact that this step is ‘destructive’ it can be executed as times as needed if some problem is detected and afterwards you fix the problem. Please, refer to the procedure log when it finishes.
This step will transfer the relations between translations stored by LinguaPlone to the PAM catalog. This step is not destructive and can be executed as many times as needed.
By default, if PAM is installed, Archetypes-based content types are marked as translatables
The language independent fields on Archetype-based content are marked the same way as in LinguaPlone:
atapi.StringField( 'myField', widget=atapi.StringWidget( .... ), languageIndependent=True ),
If you want to completely remove LinguaPlone of your installation, you should make sure that your code are dependant in any way of LP.
There are four ways of achieve it.
In your content type class declaration:
from plone.app.multilingual.dx import directives directives.languageindependent('field')
In your content type XML file declaration:
<field name="myField" type="zope.schema.TextLine" lingua:independent="true"> <description /> <title>myField</title> </field>
In your code:
from plone.app.multilingual.dx.interfaces import ILanguageIndependentField alsoProvides(ISchema['myField'], ILanguageIndependentField)
All the internal features are implemented on the package plone.app.multilingual.
The key points are:
- Each translation is a content object
- There is no canonical object
- The translation reference storage is external to the content object
- Adapt all the steps on translation
- Language get/set via an unified adapter
- Translatable marker interface(s)
Having a canonical object on the content space produces a dependency which is not orthogonal with the normal behavior of Plone. Content objects should be autonomous and you should be able to remove it. This is the reason because we removed the canonical content object. There is a canonical object on the translation infrastructure but is not on the content space.
In order to maintain the relations between the different language objects we designed a common object called a translation group. This translation group has an UUID on its own and each object member of the group stores it in the object catalog register. You can use the ITranslationManager utility to access and manipulate the members of a translation group given one object of the group.
The different aspects involved on a translation are adapted, so it’s possible to create different policies for different types, sites, etc.
ITranslationFactory - General factory used to create a new content
ITranslationLocator - Where we are going to locate the new translated content
Default : If the parent folder is translated create the content on the translated parent folder, otherwise create on the parent folder.
ITranslationCloner - Method to clone the original object to the new one
Default : Nothing
ITranslationIdChooser - Which id is the translation
Default : The original id + lang code-block
ILanguageIndependentFieldsManager - Manager for language independent fields
In order to access and modify the language of a content type regardless the type (Archetypes/Dexterity) there is a interface/adapter:
You can use:
from Products.CMFPlone.interfaces import ILanguage language = ILanguage(context).get_language()
or in case you want to set the language of a content:
language = ILanguage(context).set_language('ca')
Contributors please read the document Process for Plone core’s development
Sources are at the Plone code repository hosted at Github.