Ransack : join a table twice

ransack_join_table_twice_issue.rb

# ransack_join_table_twice_issue
# Fork from : github.com/jonatack/test-ransacker-arel-present-predicate.rb

# Run it in your console with: `ruby ransack_joins_table_twice_issue.rb`

# If you change the gem dependencies, run it with:
# `rm gemfile* && ruby ransack_join_table_twice_issue.rb`

unless File.exist?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', '5.1.4'
    # gem 'pg', '0.20'
    gem 'sqlite3'
    gem 'ransack', github: 'activerecord-hackery/ransack'
    gem 'polyamorous', github: 'activerecord-hackery/polyamorous'

  GEMFILE

  system 'bundle install'
end


require 'bundler'
Bundler.setup(:default)

require 'active_record'
require 'minitest/autorun'
require 'logger'
require 'ransack'

# This connection will do for database-independent bug reports.
# ActiveRecord::Base.establish_connection({"adapter"=>"postgresql", "encoding"=>"UTF8", "host"=>"localhost", "database"=>"test-database", "username"=>"######", "password"=>"######"})
ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

# Display versions.
message = "Running test case with Ruby #{RUBY_VERSION}, Active Record #{
  ::ActiveRecord::VERSION::STRING}, Arel #{Arel::VERSION} and #{
  ::ActiveRecord::Base.connection.adapter_name}"
line = '=' * message.length
puts line, message, line


# Define DB structure
ActiveRecord::Schema.define do
  create_table :molecules, force: true do |t|
    t.string :name
  end

  create_table :parameters, force: true do |t|
    t.string :name
    t.string :value
    t.integer :parameterable_id
    t.string :parameterable_type
    t.integer :parameters_group_id
    t.integer :parameter_definition_id
  end

  create_table :parameters_groups, force: true do |t|
    t.string :name
  end

  create_table :parameter_definitions, force: true do |t|
    t.string :name
  end
end

# Define classes
class Molecule < ActiveRecord::Base
  has_many :identifier_parameters, as: :parameterable, :class_name => "Parameter"
end

class Parameter < ActiveRecord::Base
  belongs_to :parameters_group
  belongs_to :parameterable, polymorphic: :true
  belongs_to :parameter_definition

  def self.ransackable_attributes(auth_object = nil)
  %w(name value) + _ransackers.keys
  end

  ransacker :value_to_f do
      Arel.sql("CAST(parameters_parameters_groups.value as float)")
  end

  ransacker :pg_value_to_f do
      Arel.sql("CAST(parameters.value as float)")
  end

end

class ParametersGroup < ActiveRecord::Base
  has_many :parameters, dependent: :destroy
end

class ParameterDefinition < ActiveRecord::Base
  has_many :parameters

  def self.ransackable_attributes(auth_object = nil)
    %w(name id) + _ransackers.keys
  end

end


# Run test
## Joins do not behave as intented

class BugTest < Minitest::Test
  def test_ransack_joins
    sql = Molecule.ransack(
      {
        identifier_parameters_parameters_group_parameters_parameter_definition_id_eq: 1,
        identifier_parameters_parameters_group_parameters_value_to_f_lt: 5
      }
    ).result.to_sql

    puts sql

    assert_equal('SELECT "molecules".* FROM "molecules" LEFT OUTER JOIN "parameters" ON "parameters"."parameterable_id" = "molecules"."id" AND "parameters"."parameterable_type" = \'Molecule\' LEFT OUTER JOIN "parameters_groups" ON "parameters_groups"."id" = "parameters"."parameters_group_id" LEFT OUTER JOIN "parameters" "parameters_parameters_groups" ON "parameters_parameters_groups"."parameters_group_id" = "parameters_groups"."id" LEFT OUTER JOIN "parameter_definitions" ON "parameter_definitions"."id" = "parameters_parameters_groups"."parameter_definition_id" WHERE ("parameter_definitions"."id" = 1 AND CAST(parameters_parameters_groups.value as float) < \'5\')', sql)
  end
end