Get search dictionary based on I18n.default_locale (merge pull request #3856)

Implementation tries to be open for further extensions, such as deciding on
search dictionary based on configuration option or by locale set for
given user.

app/models/concerns/search_cache.rb

@@ -19,7 +19,8 @@ module SearchCache
     end
 
     def set_tsvector(value, weight)
-      "setweight(to_tsvector('spanish', unaccent(coalesce(#{quote(strip_html(value))}, ''))), #{quote(weight)})"
+      dict = quote(SearchDictionarySelector.call)
+      "setweight(to_tsvector(#{dict}, unaccent(coalesce(#{quote(strip_html(value))}, ''))), #{quote(weight)})"
     end
 
     def quote(value)

app/models/concerns/searchable.rb

@@ -5,14 +5,18 @@ module Searchable
     include PgSearch
     include SearchCache
 
-    pg_search_scope :pg_search, {
-      against: :ignored, # not used since using a tsvector_column
-      using: {
-        tsearch: { tsvector_column: "tsv", dictionary: "spanish", prefix: true }
-      },
-      ignoring: :accents,
-      ranked_by: "(:tsearch)",
-      order_within_rank: (column_names.include?("cached_votes_up") ? "#{table_name}.cached_votes_up DESC" : nil)
-    }
+    pg_search_scope :pg_search, ->(query) do
+      cached_votes_up_present = column_names.include?("cached_votes_up")
+      {
+        against: :ignored, # not used since using a tsvector_column
+        using: {
+          tsearch: { tsvector_column: "tsv", dictionary: SearchDictionarySelector.call, prefix: true }
+        },
+        ignoring: :accents,
+        ranked_by: "(:tsearch)",
+        order_within_rank: (cached_votes_up_present ? "#{table_name}.cached_votes_up DESC" : nil),
+        query: query
+      }
+    end
   end
 end