ROM(PG, Sequel) + Dry-v example

code.rb

#!/usr/bin/env ruby

require 'bundler/inline'

DB_URL = "postgres://localhost/gotar"

gemfile(true) do
  source 'https://rubygems.org'

  gem 'pg'
  gem 'rom', '~> 5.1'
  gem 'rom-sql', '~> 3.0'
  gem "dry-validation", "~> 1.4"

  gem "pry"
end

require 'rom'
require 'rom-sql'
require 'dry-validation'
require 'logger'

config = ROM::Configuration.new(:sql, 'postgres://localhost/gotar')
conn = config.gateways[:default].use_logger(Logger.new($stdout))
conn = config.gateways[:default].connection

conn.create_table(:foo) do
  primary_key :id
  column :name, String
end

config.relation(:foo) do
  schema(infer: true)
end

$rom = ROM.container(config)

class Schema < Dry::Validation::Contract
  option :id

  params do
    required(:name).filled
  end

  rule(:name) do
    key.failure("must be unique") if $rom.relations[:foo].where(name: value).where{ id.not(id) }.exist?
  end
end

validation = Schema.new(id: 1).call({name: "foo"})
validation.success?

conn.drop_table(:foo)