This Drupal extension provides a simple Views filter that handles complex content negotiation rules for you. It can be very useful if you use the Content Translation module on Drupal sites with content in various states of translation completeness.
This module assumes you already have the Views and Content Translation modules installed and enabled. You can enable this module like you enable any other Drupal module.
Once installed, go to an existing content View, or create a new content View, and click "Add" in the filter criteria section. This will open the "Add filter criteria" dialogue.
In the dialogue, search for the "Content translation: Fallback" filter, check it, then press "Add and configure filter criteria."
You can optionally configure the "fallback language" for this filter; it will default to the site's default language.
What does this filter do, exactly? Before we answer that, a little background!
Drupal Core provides a way to translate content using a paradigm called "Content Translation" (used to differentiate an alternate translation paradigm known as Entity Field Translation).
The content translation paradigm works by storing translations of content in
distinct nodes that are conceptually linked together in a "translation set." On
any given node, you can find the "master" node, from which other nodes have been
translated, by checking against the node's tnid property (representing the
nid of the master node in the translation set).
Using this paradigm, it becomes necessary to apply a language filter to every content View, indicating that only content in the current site's language should be returned and displayed.
On site's that allow content to be in a "language neutral" state, it's necessary to make the aforementioned language filter include "language neutral" in addition to the "current site language" filter criteria.
The problem with this technique is that it simply doesn't show content from a given translation set if there's no content in the set that matches the current site language (e.g. an English piece of content is translated into French, but the View is being loaded on the Spanish site).
In many cases, it's desirable to "fall back" to a default language, but setting up a filter to manage this can be quite cumbersome, and is not very easy to scale across all Views across your site.
The way to work around this problem is somewhat complex:
- You must add a relationship to your View,
LEFT JOINing the node table onto itself using the tnid. - You must
ORyour usual current language and language neutral content language filter with another language filter, checking for your fallback language, andANDing it with a check to make sure the node ID of the joined node table is empty.
Due to the nature of condition groups in Views, this can be extremely cumbersome to manage, especially on more complex Views.
This module solves the problem by packaging the above relationship/filter group combination into a single filter criterion that you can add to any view. No Views relationships or filter group knowledge necessary.