Upgrading causes breaking change: "PG::FeatureNotSupported: ERROR: input of anonymous composite types is not implemented"

[danielpclark]

In Rails 6.0.3 And Ransack 2.3.2 this passes. But when you upgrade to Ransack 2.4.0 (and later), with or without Rails 6.1.4, the IN (('major 1', '')) changes to IN ('major 1', '') causing the error:

ActiveRecord::StatementInvalid:
    PG::FeatureNotSupported: ERROR:  input of anonymous composite types is not implemented
    LINE 1: ...OALESCE(TRIM("degrees"."concentration"), '')) IN ('major 1',...

Here is the bug reproduction (just changing versions):

# frozen_string_literal: true

unless File.exist?('Gemfile')
  File.write('Gemfile', %q(
    source 'https://rubygems.org'

    git_source(:github) { |repo| "https://github.com/#{repo}.git" }

    gem 'rails', github: 'rails/rails', tag: 'v6.0.3'
    gem 'ransack', '~> 2.4.2'
    gem 'sqlite3'
  ))

  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: '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

ActiveRecord::Schema.define do
  create_table :degrees, force: true do |t|
    t.string :concentration
    t.string :major
  end
end

# Model
class Degree < ActiveRecord::Base
  ransacker :major_concentration, formatter: lambda { |tuples|
    major, concentration = JSON.parse(tuples)
    Arel::Nodes::Grouping.new(
      [
        Arel::Nodes.build_quoted(major),
        Arel::Nodes.build_quoted(concentration)
      ]
    )
  } do |_parent|
    degrees = Degree.arel_table
    Arel::Nodes::Grouping.new(
      %i[major concentration].map do |field|
        Arel::Nodes::NamedFunction.new(
          'COALESCE',
          [
            Arel::Nodes::NamedFunction.new('TRIM', [degrees[field]]),
            Arel::Nodes.build_quoted('')
          ]
        )
      end
    )
  end
end

# Bug Test
class BugTest < Minitest::Test
  def test_ransack
    ransack_hash = ActiveSupport::HashWithIndifferentAccess.new(
      {
        m: 'and',
        g: [
          ActiveSupport::HashWithIndifferentAccess.new({ major_concentration_in: ['["major 1", ""]'] })
        ]
      }
    )
    sql = Degree.ransack(ransack_hash).result.to_sql
    puts sql
    assert_equal "SELECT \"degrees\".* FROM \"degrees\" WHERE (COALESCE(TRIM(\"degrees\".\"major\"), ''), COALESCE(TRIM(\"degrees\".\"concentration\"), '')) IN (('major 1', ''))", sql
  end
end

The breaking change was introduced in commit 93615c3 and the method causing this issue is method casted_array?.

The Arel generated changes from

@right=[#<Arel::Nodes::Grouping:0x00005653904e6f58 @expr=[#<Arel::Nodes::Quoted:0x00005653904e6fd0 @expr="major 1">,#<Arel::Nodes::Quoted:0x00005653904e6fa8 @expr="">]>]>,

to

@right=[[#<Arel::Nodes::Quoted:0x0000562801598da8 @expr="major 1">,#<Arel::Nodes::Quoted:0x0000562801598d80 @expr="">]]>,

Any help/fix would be appreciated as this is a blocker in an app Rails upgrade at work.

[danielpclark]

I've submitted a PR that resolves this by fixing the casted array checking and handling logic.

[scarroll32]

Thank you @danielpclark