add monkey patch for joining with ONLY keyword (#35)

* monkey patch for join on only

* update comment

Rakefile

@@ -10,12 +10,11 @@ Rake::TestTask.new(:test) do |t|
   t.test_files = FileList["test/**/test_*.rb"]
 end
 
-SOURCE_FILES = %w[**/*.rb Rakefile Gemfile bin/console]
+SOURCE_FILES = %w[test/**/*.rb lib/**/*.rb Rakefile Gemfile bin/console hoardable.gemspec]
 
 SyntaxTree::Rake::CheckTask.new(:check) do |t|
   t.source_files = SOURCE_FILES
   t.print_width = 100
-  t.ignore_files = "vendor/**/*.rb"
 end
 
 SyntaxTree::Rake::WriteTask.new(:write) do |t|

hoardable.gemspec

@@ -1,36 +1,39 @@
 # frozen_string_literal: true
 
-require_relative 'lib/hoardable/version'
+require_relative "lib/hoardable/version"
 
 Gem::Specification.new do |spec|
-  spec.name = 'hoardable'
+  spec.name = "hoardable"
   spec.version = Hoardable::VERSION
-  spec.authors = ['justin talbott']
-  spec.email = ['[email protected]']
+  spec.authors = ["justin talbott"]
+  spec.email = ["[email protected]"]
 
-  spec.summary = 'An ActiveRecord extension for versioning and soft-deletion of records in Postgres'
-  spec.description = 'Rails model versioning with the power of uni-temporal inherited tables'
-  spec.homepage = 'https://github.com/waymondo/hoardable'
-  spec.license = 'MIT'
-  spec.required_ruby_version = '>= 2.7.0'
+  spec.summary = "An ActiveRecord extension for versioning and soft-deletion of records in Postgres"
+  spec.description = "Rails model versioning with the power of uni-temporal inherited tables"
+  spec.homepage = "https://github.com/waymondo/hoardable"
+  spec.license = "MIT"
+  spec.required_ruby_version = ">= 3.0"
 
-  spec.metadata['homepage_uri'] = spec.homepage
-  spec.metadata['source_code_uri'] = spec.homepage
-  spec.metadata['rubygems_mfa_required'] = 'true'
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+  spec.metadata["rubygems_mfa_required"] = "true"
 
-  spec.files = Dir.chdir(File.expand_path(__dir__)) do
-    `git ls-files -z`.split("\x0").reject do |f|
-      (f == __FILE__) || f.match(%r{\A(?:(?:bin|test|spec|features)/|\.(?:git|travis|circleci)|appveyor)})
+  spec.files =
+    Dir.chdir(File.expand_path(__dir__)) do
+      `git ls-files -z`.split("\x0")
+        .reject do |f|
+          (f == __FILE__) ||
+            f.match(%r{\A(?:(?:bin|test|spec|features)/|\.(?:git|travis|circleci)|appveyor)})
+        end
     end
-  end
-  spec.bindir = 'exe'
+  spec.bindir = "exe"
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
-  spec.require_paths = ['lib']
+  spec.require_paths = ["lib"]
 
-  spec.add_dependency 'activerecord', '>= 6.1', '< 8'
-  spec.add_dependency 'activesupport', '>= 6.1', '< 8'
-  spec.add_dependency 'railties', '>= 6.1', '< 8'
+  spec.add_dependency "activerecord", ">= 7", "< 8"
+  spec.add_dependency "activesupport", ">= 7", "< 8"
+  spec.add_dependency "railties", ">= 7", "< 8"
 
-  spec.add_dependency 'fx', '>= 0.8', '< 1'
-  spec.add_dependency 'pg', '>= 1', '< 2'
+  spec.add_dependency "fx", ">= 0.8", "< 1"
+  spec.add_dependency "pg", ">= 1", "< 2"
 end

lib/hoardable.rb

@@ -3,6 +3,7 @@
 require "active_record"
 require "fx"
 require_relative "hoardable/version"
+require_relative "hoardable/arel_visitors"
 require_relative "hoardable/engine"
 require_relative "hoardable/finder_methods"
 require_relative "hoardable/scopes"

lib/hoardable/arel_visitors.rb

@@ -0,0 +1,51 @@
+module Hoardable
+  # This is a monkey patch of JOIN related {Arel::Visitors} for PostgreSQL so that they can append
+  # the ONLY clause when known to be operating on a {Hoardable::Model}. Ideally, {Arel} itself would
+  # provide a mechanism to support this keyword.
+  module ArelVisitors
+    def visit_Arel_Nodes_FullOuterJoin(o, collector)
+      collector << "FULL OUTER JOIN "
+      hoardable_maybe_add_only(o, collector)
+      collector = visit o.left, collector
+      collector << " "
+      visit o.right, collector
+    end
+
+    def visit_Arel_Nodes_OuterJoin(o, collector)
+      collector << "LEFT OUTER JOIN "
+      hoardable_maybe_add_only(o, collector)
+      collector = visit o.left, collector
+      collector << " "
+      visit o.right, collector
+    end
+
+    def visit_Arel_Nodes_RightOuterJoin(o, collector)
+      collector << "RIGHT OUTER JOIN "
+      hoardable_maybe_add_only(o, collector)
+      collector = visit o.left, collector
+      collector << " "
+      visit o.right, collector
+    end
+
+    def visit_Arel_Nodes_InnerJoin(o, collector)
+      collector << "INNER JOIN "
+      hoardable_maybe_add_only(o, collector)
+      collector = visit o.left, collector
+      if o.right
+        collector << " "
+        visit(o.right, collector)
+      else
+        collector
+      end
+    end
+
+    private def hoardable_maybe_add_only(o, collector)
+      return unless o.left.instance_variable_get("@klass").in?(Hoardable::REGISTRY)
+      return if Hoardable.instance_variable_get("@at")
+
+      collector << "ONLY "
+    end
+  end
+end
+
+Arel::Visitors::PostgreSQL.prepend Hoardable::ArelVisitors

lib/hoardable/engine.rb

@@ -2,6 +2,8 @@
 
 # An +ActiveRecord+ extension for keeping versions of records in uni-temporal inherited tables.
 module Hoardable
+  REGISTRY = Set.new
+
   # Symbols for use with setting contextual data, when creating versions. See
   # {file:README.md#tracking-contextual-data README} for more.
   DATA_KEYS = %i[meta whodunit event_uuid].freeze

lib/hoardable/has_many.rb

@@ -12,9 +12,7 @@ def scope
         @scope ||= hoardable_scope
       end
 
-      private
-
-      def hoardable_scope
+      private def hoardable_scope
         if Hoardable.instance_variable_get("@at") &&
              (hoardable_id = @association.owner.hoardable_id)
           @association.scope.rewhere(@association.reflection.foreign_key => hoardable_id)

lib/hoardable/model.rb

@@ -67,6 +67,7 @@ def with_hoardable_config(hash)
             object_namespace.const_set(version_class_name, Class.new(self) { include VersionModel })
           end
           include SourceModel
+          REGISTRY.add(self)
 
           trace.disable
         end

test/support/models.rb

@@ -57,7 +57,7 @@ class PostWithUnhoardableRichText < ActiveRecord::Base
 
 class User < ActiveRecord::Base
   include Hoardable::Model
-  has_many :posts
+  has_many :posts, hoardable: true
   has_one :profile, hoardable: true
   has_rich_text :bio, hoardable: true
   serialize :preferences, coder: JSON