<img src=“upload.wikimedia.org/wikipedia/commons/2/29/Postgresql_elephant.svg” height=“64px”/>
This small Ruby gem helps you integrate PostgreSQL with your Ruby web app, through Liquibase. It also adds a simple connection pool and query processor, to make SQL manipulation simpler.
First of all, on top of Ruby and Bundler you need to have PostgreSQL, Java 8+, and Maven 3.2+ installed. In Ubuntu 16+ this should be enough:
$ sudo apt-get install -y postgresql-10 postgresql-client-10 $ sudo apt-get install -y default-jre maven
Then, add this to your {Gemfile
}:
gem 'pgtk'
Then, add this to your {Rakefile
}:
require 'pgtk/pgsql_task' Pgtk::PgsqlTask.new :pgsql do |t| t.dir = 'target/pgsql' # Temp directory with PostgreSQL files t.fresh_start = true # To delete the directory on every start t.user = 'test' t.password = 'test' t.dbname = 'test' t.yaml = 'target/pgsql-config.yml' # YAML file to be created with connection details end
And this too:
require 'pgtk/liquibase_task' Pgtk::LiquibaseTask.new liquibase: :pgsql do |t| t.master = 'liquibase/master.xml' # Master XML file path t.yaml = ['target/pgsql-config.yml', 'config.yml'] # YAML files with connection details end
You should create that liquibase/master.xml
file in your repository, and a number of other XML files with Liquibase changes. This example will help you understand them.
Now, you can do this:
$ bundle exec rake pgsql liquibase
A temporary PostgreSQL server will be started and the entire set of Liquibase SQL changes will be applied. You will be able to connect to it from your application, using the file target/config.yml
.
From inside your app you may find this class useful:
require 'pgtk/pool' pgsql = Pgtk::Pool.new(Pgtk::Wire::Yaml.new('config.yml')) pgsql.start(5) # Start it with five simultaneous connections
You can also let it pick the connection parameters from the environment variable DATABASE_URL
, formatted like postgres://user:password@host:5432/dbname
:
pgsql = Pgtk::Pool.new(Pgtk::Wire::Env.new)
Now you can fetch some data from the DB:
name = pgsql.exec('SELECT name FROM user WHERE id = $1', [id])[0]['name']
You may also use it if you need to run a transaction:
pgsql.transaction do |t| t.exec('DELETE FROM user WHERE id = $1', [id]) t.exec('INSERT INTO user (name, phone) VALUES ($1, $2)', [name, phone]) end
To make your PostgreSQL database visible in your unit test, I would recommend you create a method test_pgsql
in your test__helper.rb
file (which is required
in all unit tests) and implement it like this:
require 'yaml' require 'minitest/autorun' require 'pgtk/pool' module Minitest class Test def test_pgsql config = YAML.load_file() @@test_pgsql ||= Pgtk::Pool.new( Pgtk::Wire::Yaml.new('target/pgsql-config.yml') ).start end end end
Should work.
Well, it works in wts.zold.io, mailanes.com, and 0rsk.com. They are all open source, you can see how they use pgtk
.
How to contribute¶ ↑
Read these guidelines. Make sure your build is green before you contribute your pull request. You will need to have Ruby 2.3+ and Bundler installed. Then:
$ bundle update $ bundle exec rake
If it's clean and you don't see any error messages, submit your pull request.