Rails activeRecord patch and commit - ruby-on-rails

Question

I'm working on a tagged blog system using rails. Now it works using join table, but I have some doubt on performance.
Now every time I create a blog and its associating tags, it commits to database every single statement. I think better practice should be patch all these statements and commit to database only once. Is it possible in rails?
Create log dump:
Started POST "/articles" for 127.0.0.1 at 2014-08-29 15:30:48 -0400
Processing by ArticlesController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"K4rWQEh0810X2jMe/Z9pC/PN2WeOcO0F0TkjKUZTPec=", "title"=>"test27", "text"=>"ddddd", "tag"=>"a,k,g", "commit"=>"Submit"}
Unpermitted parameters: utf8, authenticity_token, tag, commit
(0.9ms) BEGIN
SQL (0.3ms) INSERT INTO `articles` (`created_at`, `text`, `title`, `updated_at`) VALUES ('2014-08-29 19:30:48', 'ddddd', 'test27', '2014-08-29 19:30:48')
(0.2ms) COMMIT
Tag Load (0.3ms) SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'a' LIMIT 1
(0.2ms) BEGIN
SQL (0.3ms) INSERT INTO `articles_tags` (`article_id`, `tag_id`) VALUES (28, 1)
(0.2ms) COMMIT
Tag Load (0.2ms) SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'k' LIMIT 1
(0.1ms) BEGIN
SQL (0.2ms) INSERT INTO `tags` (`name`) VALUES ('k')
(0.1ms) COMMIT
(0.1ms) BEGIN
SQL (0.3ms) INSERT INTO `articles_tags` (`article_id`, `tag_id`) VALUES (28, 17)
(8.3ms) COMMIT
Tag Load (0.3ms) SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'g' LIMIT 1
(0.1ms) BEGIN
SQL (0.2ms) INSERT INTO `tags` (`name`) VALUES ('g')
(0.1ms) COMMIT
(0.1ms) BEGIN
SQL (0.4ms) INSERT INTO `articles_tags` (`article_id`, `tag_id`) VALUES (28, 18)
(0.2ms) COMMIT
Model design:
class Article < ActiveRecord::Base
has_and_belongs_to_many :tag
end
class Tag < ActiveRecord::Base
has_and_belongs_to_many :article, :uniq => true
end
Blog create code:
def create
#article = Article.new(article_params)
tag_arr = params[:tag].split(',')
if #article.save
tag_arr.each do |name|
tag = Tag.find_or_create_by(name: name) # create a new tag only if tag.name not exist
#article.tag << tag
end
redirect_to #article
else
render 'new'
end
end

Answer 1

To save the article and tags in a single transaction, wrap the operations in a transaction block.
def create
#article = Article.new(article_params)
tag_arr = params[:tag].split(',')
Article.transaction do
if #article.save
tag_arr.each do |name|
article.tags.find_or_create_by(name: name)
end
end
end
if #article.new_record?
render 'new'
else
redirect_to #article
end
end
This will result in SQL queries something like:
(0.9ms) BEGIN
SQL (0.3ms) INSERT INTO `articles` (`created_at`, `text`, `title`, `updated_at`) VALUES ('2014-08-29 19:30:48', 'ddddd', 'test27', '2014-08-29 19:30:48')
Tag Load (0.3ms) SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'a' LIMIT 1
SQL (0.3ms) INSERT INTO `articles_tags` (`article_id`, `tag_id`) VALUES (28, 1)
Tag Load (0.2ms) SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'k' LIMIT 1
SQL (0.2ms) INSERT INTO `tags` (`name`) VALUES ('k')
SQL (0.3ms) INSERT INTO `articles_tags` (`article_id`, `tag_id`) VALUES (28, 17)
Tag Load (0.3ms) SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'g' LIMIT 1
SQL (0.2ms) INSERT INTO `tags` (`name`) VALUES ('g')
SQL (0.4ms) INSERT INTO `articles_tags` (`article_id`, `tag_id`) VALUES (28, 18)
(0.2ms) COMMIT