[#2199] Translate facets on dataset search page

ckanext/multilingual/plugin.py
Add after_search() method that looks up translations of facet items and
puts them in a translations dict in the pylons template context.

ckan/lib/helpers.py:facet_items()
Append a third value to each facet item: its translated name from the
translations dict.

ckan/templates/facets.html:facet_sidebar()
Use the translated names put into the facet items by facet_items().

ckan/lib/helpers.py

@@ -223,8 +223,22 @@ def facet_items(c, name, limit=10):
         if not len(k.strip()):
             continue
         if not (name, k) in request.params.items():
-            facets.append((k, v))
-    return sorted(facets, key=lambda (k, v): v, reverse=True)[:limit]
+            facets.append([k, v])
+
+    # Append a third value to each facet item: the translated name of the facet
+    # item, to be displayed to the user. Translations are looked for in a
+    # 'translations' dict in the Pylons context.
+    for facet in facets:
+        name, count = facet
+        if c.translations:
+            facet.append(c.translations.get(name, name))
+        else:
+            # If there is no translations dict in the context, just use the
+            # facet item's untranslated name.
+            facet.append(name)
+
+    return sorted(facets, key=lambda (name, count, translated_name): 
+            translated_name, reverse=True)[:limit]
 
 def facet_title(name):
     from pylons import config

ckan/templates/facets.html

@@ -9,9 +9,10 @@
     <div py:if="len(h.facet_items(c, code, limit=limit))" class="facet-box">
         <h2>${title(code)}</h2>
         <ul class="facet-options">
-            <li py:for="name, count in h.facet_items(c, code, limit=limit)"
+            <li py:for="name, count, translated_name in h.facet_items(c,
+                    code, limit=limit)"
                 py:if="not (code, name) in c.fields">
-                <a href="${c.drill_down_url(**{code: name})}">${label(name)}</a> (${count})
+                <a href="${c.drill_down_url(**{code: name})}">${label(translated_name)}</a> (${count})
             </li>
         </ul>
     </div>

ckanext/multilingual/plugin.py

@@ -1,3 +1,4 @@
+import sets
 import ckan
 from ckan.plugins import SingletonPlugin, implements, IPackageController
 import pylons
@@ -33,6 +34,52 @@ def before_search(self, search_params):
 
         return search_params
 
+    def after_search(self, search_results, search_params):
+
+        facets = search_results.get('facets')
+        if not facets:
+            return search_results
+
+        desired_lang_code = pylons.request.environ['CKAN_LANG']
+        fallback_lang_code = pylons.config.get('ckan.locale_default', 'en')
+
+        # Look up all the term translations in one db query.
+        terms = sets.Set()
+        for facet in facets.values():
+            for name, count in facet.items():
+                terms.add(name)
+        translations = ckan.logic.action.get.term_translation_show(
+                {'model': ckan.model},
+                {'terms': terms,
+                    'lang_codes': (desired_lang_code, fallback_lang_code)})
+
+        # Add translations of facet items to a translations dict in the pylons
+        # template context.
+        pylons.c.translations = {}
+        for facet in facets.values():
+            for name, count in facet.items():
+                matching_translations = [translation for translation
+                        in translations
+                        if translation['term'] == name
+                        and translation['lang_code'] == desired_lang_code]
+                if not matching_translations:
+                    # If no translation in desired language then look for one
+                    # in fallback language.
+                    matching_translations = [translation for translation
+                            in translations
+                            if translation['term'] == name
+                            and translation['lang_code'] == fallback_lang_code]
+                assert len(matching_translations) in (0,1)
+                if matching_translations:
+                    pylons.c.translations[name] = (
+                            matching_translations[0]['term_translation'])
+                else:
+                    # If no translation in either desired or fallback language,
+                    # just use the item name itself, untranslated.
+                    pylons.c.translations[name] = name
+
+        return search_results
+
     def before_view(self, data_dict):
         desired_lang_code = pylons.request.environ['CKAN_LANG']
         fallback_lang_code = pylons.config.get('ckan.locale_default', 'en')
@@ -43,8 +90,7 @@ def before_view(self, data_dict):
 
         # Get a simple flat list of all the terms to be translated, from the
         # flattened data dict.
-        from sets import Set
-        terms = Set()
+        terms = sets.Set()
         for (key, value) in flattened.items():
             if value in (None, True, False):
                 continue