support different column weights in full text index

searchable.rb

@@ -19,19 +19,35 @@
 #   Post.search("hello")
 #   Post.search("hello", :index => :title_only)
 module Searchable
-  def searchable(columns, opts = {})
-    opts[:index] ||= 'search'
-    __searches[opts[:index]] = columns
+  def searchable(columns, options = {})
+    index_name = options.fetch(:index, 'search')
+    __searches[index_name] = columns
   end
 
-  def search(q, opts = {})
-    opts[:index] ||= 'search'
-    finder = all(opts.except(:index, :conditions).merge(:conditions => [
-      "#{opts[:index]}_vector @@ plainto_tsquery('english', ?)", q]))
-    finder &= all(opts[:conditions]) if opts[:conditions]
+  def search(query, options = {})
+    index_name = options.fetch(:index, 'search')
+    finder = all(options.except(:index, :conditions).merge(
+      :conditions => ["#{index_name}_vector @@ plainto_tsquery('english', ?)", query]
+    ))
+    finder &= all(options[:conditions]) if options[:conditions]
     finder
   end
 
+  def search_raw query, options = {}
+    limit  = options.fetch(:limit, 50)
+    page   = (options[:page] || 1).to_i
+    offset = (page - 1)*limit
+    repository.adapter.select <<-SQL, query, limit, offset
+      SELECT
+        document_id, title, abstract, publish_date, obsoleted,
+        ts_rank_cd(search_vector, query) AS search_rank
+      FROM #{storage_name}, plainto_tsquery('english', ?) query
+      WHERE search_vector @@ query
+      ORDER BY search_rank DESC
+      LIMIT ? OFFSET ?
+    SQL
+  end
+
   def auto_migrate_up!(repository_name)
     super
 
@@ -49,34 +65,52 @@ def auto_migrate_up!(repository_name)
   private
 
   def create_alter_table_sql(repository_name, name)
-    <<-EOS
+    <<-SQL
       ALTER TABLE #{storage_name(repository_name)}
         ADD COLUMN #{name}_vector tsvector NOT NULL
-    EOS
+    SQL
   end
 
   def create_index_sql(repository_name, name)
-    <<-EOS
+    <<-SQL
       CREATE INDEX #{storage_name(repository_name)}_#{name}_vector_idx
         ON #{storage_name(repository_name)} USING gin(#{name}_vector)
-    EOS
+    SQL
   end
 
   def create_trigger_sql(repository_name, name, columns)
-    <<-EOS
-      CREATE TRIGGER #{storage_name(repository_name)}_#{name}_vector_refresh
-        BEFORE INSERT OR UPDATE ON #{storage_name(repository_name)}
-      FOR EACH ROW EXECUTE PROCEDURE
-        tsvector_update_trigger(#{name}_vector, 'pg_catalog.english',
-          #{column_sql(columns)});
-    EOS
+    table_name = storage_name(repository_name)
+    vector_column = "#{name}_vector"
+
+    case columns
+    when Array
+      column_sql = columns.map {|col| send(col).field }.join(', ')
+      trigger = "tsvector_update_trigger(#{vector_column}, 'pg_catalog.english', #{column_sql})"
+      create_function = ''
+    when Hash
+      trigger = "#{table_name}_tsvector_update()"
+      create_function = <<-SQL
+        CREATE FUNCTION #{trigger} RETURNS trigger AS $$
+        begin
+          new.#{vector_column} :=
+             #{columns.map {|col,w| "setweight(to_tsvector('pg_catalog.english', coalesce(new.#{col},'')), '#{w}')" }.join(" ||\n" + ' '*13)};
+          return new;
+        end
+        $$ LANGUAGE plpgsql;
+      SQL
+    else
+      raise ArgumentError, "unknown type: #{columns.class}"
+    end
+
+    <<-SQL
+      #{create_function}
+      CREATE TRIGGER #{table_name}_#{name}_vector_refresh
+        BEFORE INSERT OR UPDATE ON #{table_name}
+      FOR EACH ROW EXECUTE PROCEDURE #{trigger};
+    SQL
   end
 
   def __searches
     @__searches ||= {}
   end
-
-  def column_sql(columns)
-    columns.map {|column| send(column).field }.join(", ")
-  end
 end