I've been working on a multilingual site that has a product finder. We have 3 exposed filters that allow a user to select an Activity, IP Category, or Industry. All of these filters are Taxonomy Term filters. Some of the terms throughout those vocabularies have a specific language set, and should only show when that language is active.

The first step is to make sure the output (Views results) only shows products where the node language matches the current language. This is easy using the built in Node translation: Language = Current user's language filter.

Quick Tip: Getting a list of taxonomy terms is easy using a view (type: Taxonomy). Trying to get only terms at the highest level is a bit trickier. One method I came up with is to add a Taxonomy: Parent term argument on the view. The key is to tell the argument to Provide default argument of PHP Code and set the value to

return 0;

The result is that only top-level terms (terms without parents) are returned.

This function returns an array of taxonomy term objects. It is much like taxonomy_get_tree(), and it does in fact use this function. We had a client that wanted a grid of product categories with an image for each term, but only for terms that have at least X associated nodes. This problem was solved using the function below, as well as another custom function to alter the views query (I'll post about this later).