Columns filtering: blacklisting or whitelisting

lib/generators/logidze/install/templates/migration.rb.erb

@@ -15,8 +15,15 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
       SQL
     end
 
+    <% if update? %>
     execute <<-SQL
-      CREATE OR REPLACE FUNCTION logidze_version(v bigint, data jsonb) RETURNS jsonb AS $body$
+      DROP FUNCTION IF EXISTS logidze_version(bigint, jsonb);
+      DROP FUNCTION IF EXISTS logidze_snapshot(jsonb);
+    SQL
+    <% end %>
+
+    execute <<-SQL
+      CREATE OR REPLACE FUNCTION logidze_version(v bigint, data jsonb, blacklist text[] DEFAULT '{}') RETURNS jsonb AS $body$
         DECLARE
           buf jsonb;
         BEGIN
@@ -26,7 +33,7 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
                    'v',
                     v,
                     'c',
-                    logidze_exclude_keys(data, 'log_data')
+                    logidze_exclude_keys(data, VARIADIC array_append(blacklist, 'log_data'))
                    );
           IF coalesce(#{current_setting('logidze.responsible')}, '') <> '' THEN
             buf := jsonb_set(buf, ARRAY['r'], to_jsonb(current_setting('logidze.responsible')));
@@ -36,12 +43,12 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
       $body$
       LANGUAGE plpgsql;
 
-      CREATE OR REPLACE FUNCTION logidze_snapshot(item jsonb) RETURNS jsonb AS $body$
+      CREATE OR REPLACE FUNCTION logidze_snapshot(item jsonb, blacklist text[] DEFAULT '{}') RETURNS jsonb AS $body$
         BEGIN
           return json_build_object(
             'v', 1,
             'h', jsonb_build_array(
-                   logidze_version(1, item)
+                   logidze_version(1, item, blacklist)
                  )
             );
         END;
@@ -103,20 +110,22 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
           merged jsonb;
           iterator integer;
           item record;
+          columns_blacklist text[];
         BEGIN
+          columns_blacklist := TG_ARGV[1];
 
           IF TG_OP = 'INSERT' THEN
 
-            NEW.log_data := logidze_snapshot(to_jsonb(NEW.*));
+            NEW.log_data := logidze_snapshot(to_jsonb(NEW.*), columns_blacklist);
 
           ELSIF TG_OP = 'UPDATE' THEN
 
             IF OLD.log_data is NULL OR OLD.log_data = '{}'::jsonb THEN
-              NEW.log_data := logidze_snapshot(to_jsonb(NEW.*));
+              NEW.log_data := logidze_snapshot(to_jsonb(NEW.*), columns_blacklist);
               RETURN NEW;
             END IF;
 
-            history_limit := TG_ARGV[0];
+            history_limit := NULLIF(TG_ARGV[0], 'null');
             current_version := (NEW.log_data->>'v')::int;
 
             IF NEW = OLD THEN
@@ -149,7 +158,7 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
             NEW.log_data := jsonb_set(
               NEW.log_data,
               ARRAY['h', size::text],
-              logidze_version(new_v, changes),
+              logidze_version(new_v, changes, columns_blacklist),
               true
             );
 
@@ -174,9 +183,9 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
   def down
     <% unless update? %>
     execute <<-SQL
-      DROP FUNCTION logidze_version(bigint, jsonb) CASCADE;
+      DROP FUNCTION logidze_version(bigint, jsonb, text[]) CASCADE;
       DROP FUNCTION logidze_compact_history(jsonb) CASCADE;
-      DROP FUNCTION logidze_snapshot(jsonb) CASCADE;
+      DROP FUNCTION logidze_snapshot(jsonb, text[]) CASCADE;
       DROP FUNCTION logidze_logger() CASCADE;
     SQL
     <% end %>

lib/generators/logidze/model/model_generator.rb

@@ -15,7 +15,14 @@ class ModelGenerator < ::ActiveRecord::Generators::Base # :nodoc:
       class_option :only_trigger, type: :boolean, optional: true,
                                   desc: "Create trigger-only migration"
 
+      class_option :blacklist, type: :array, optional: true
+      class_option :whitelist, type: :array, optional: true
+
       def generate_migration
+        if options[:blacklist] && options[:whitelist]
+          $stderr.puts "Use only one: --whitelist or --blacklist"
+          exit(1)
+        end
         migration_template "migration.rb.erb", "db/migrate/#{migration_file_name}"
       end
 
@@ -45,6 +52,38 @@ def backfill?
         def only_trigger?
           options[:only_trigger]
         end
+
+        def columns_blacklist
+          array = if !options[:whitelist]
+                    options[:blacklist]
+                  else
+                    class_name.constantize.column_names - options[:whitelist]
+                  end
+
+          array || []
+        end
+
+        def logidze_logger_parameters
+          if limit.nil? && columns_blacklist.empty?
+            ''
+          elsif !limit.nil? && columns_blacklist.empty?
+            limit
+          elsif !limit.nil? && !columns_blacklist.empty?
+            "#{limit}, #{format_pgsql_array(columns_blacklist)}"
+          elsif limit.nil? && !columns_blacklist.empty?
+            "null, #{format_pgsql_array(columns_blacklist)}"
+          end
+        end
+
+        def logidze_snapshot_parameters
+          return 'to_jsonb(t)' if columns_blacklist.empty?
+
+          "to_jsonb(t), #{format_pgsql_array(columns_blacklist)}"
+        end
+
+        def format_pgsql_array(ruby_array)
+          "'{" + ruby_array.join(', ') + "}'"
+        end
       end
 
       private

lib/generators/logidze/model/templates/migration.rb.erb

@@ -11,13 +11,13 @@ class <%= @migration_class_name %> < ActiveRecord::Migration
       CREATE TRIGGER logidze_on_<%= table_name %>
       BEFORE UPDATE OR INSERT ON <%= table_name %> FOR EACH ROW
       WHEN (coalesce(#{current_setting('logidze.disabled')}, '') <> 'on')
-      EXECUTE PROCEDURE logidze_logger(<%= limit || '' %>);
+      EXECUTE PROCEDURE logidze_logger(<%= logidze_logger_parameters %>);
     SQL
 
     <% if backfill? %>
     execute <<-SQL
       UPDATE <%= table_name %> as t
-      SET log_data = logidze_snapshot(to_jsonb(t));
+      SET log_data = logidze_snapshot(<%= logidze_snapshot_parameters %>);
     SQL
     <% end %>
   end

spec/dummy/db/schema.rb

@@ -10,10 +10,11 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160415194001) do
+ActiveRecord::Schema.define(version: 20170110144045) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
+  enable_extension "hstore"
 
   create_table "posts", force: :cascade do |t|
     t.string   "title"

spec/generators/model_generator_spec.rb

@@ -52,6 +52,17 @@ class User < ActiveRecord::Base
         end
       end
 
+      context "with columns blacklist" do
+        let(:args) { ["user", "--blacklist", "age", "active"] }
+
+        it "creates trigger with columns blacklist" do
+          is_expected.to exist
+          is_expected.to contain(
+            /execute procedure logidze_logger\(null, '\{age, active\}'\);/i
+          )
+        end
+      end
+
       context "with backfill" do
         let(:args) { ["user", "--backfill"] }