From 75c669187248d0a92f1cba09fb2f9784c80c5510 Mon Sep 17 00:00:00 2001
From: Bruno Vezoli <c-bruno.vezoli@masterclass.com>
Date: Thu, 15 Apr 2021 23:24:02 -0300
Subject: [PATCH] [1] Wharel: exposed arel, block with argument

---
 activerecord/lib/active_record/querying.rb    |  2 +-
 .../active_record/relation/query_composer.rb  | 31 +++++++++++++++++++
 .../active_record/relation/query_methods.rb   |  6 ++++
 activerecord/test/cases/relations_test.rb     | 16 ++++++++++
 4 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 activerecord/lib/active_record/relation/query_composer.rb

diff --git a/activerecord/lib/active_record/querying.rb b/activerecord/lib/active_record/querying.rb
index ceded67d57b2d..a7c894ea22f10 100644
--- a/activerecord/lib/active_record/querying.rb
+++ b/activerecord/lib/active_record/querying.rb
@@ -13,7 +13,7 @@ module Querying
       :destroy_all, :delete_all, :update_all, :touch_all, :destroy_by, :delete_by,
       :find_each, :find_in_batches, :in_batches,
       :select, :reselect, :order, :reorder, :group, :limit, :offset, :joins, :left_joins, :left_outer_joins,
-      :where, :rewhere, :invert_where, :preload, :extract_associated, :eager_load, :includes, :from, :lock, :readonly,
+      :where, :wharel, :rewhere, :invert_where, :preload, :extract_associated, :eager_load, :includes, :from, :lock, :readonly,
       :and, :or, :annotate, :optimizer_hints, :extending,
       :having, :create_with, :distinct, :references, :none, :unscope, :merge, :except, :only,
       :count, :average, :minimum, :maximum, :sum, :calculate,
diff --git a/activerecord/lib/active_record/relation/query_composer.rb b/activerecord/lib/active_record/relation/query_composer.rb
new file mode 100644
index 0000000000000..422099222fe89
--- /dev/null
+++ b/activerecord/lib/active_record/relation/query_composer.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  class QueryComposer
+    def initialize(model)
+      @model = model
+      @arel_table = model.arel_table
+      @reflections = model._reflections
+      define_attribute_accessors
+    end
+
+    def method_missing(name, *_args)
+      if reflections.key?(name.to_s)
+        self.class.new(reflections[name.to_s].klass)
+      else
+        super
+      end
+    end
+
+    private
+      attr_reader :model, :arel_table, :reflections
+
+      def define_attribute_accessors
+        model.attribute_names.each do |attr|
+          define_singleton_method attr do
+            arel_table[attr]
+          end
+        end
+      end
+  end
+end
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index c9da47482493a..ab6cf85fb37be 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -2,6 +2,7 @@
 
 require "active_record/relation/from_clause"
 require "active_record/relation/query_attribute"
+require "active_record/relation/query_composer"
 require "active_record/relation/where_clause"
 require "active_model/forbidden_attributes_protection"
 require "active_support/core_ext/array/wrap"
@@ -671,6 +672,11 @@ def where!(opts, *rest) # :nodoc:
       self
     end
 
+    def wharel(&block)
+      conditions = yield QueryComposer.new(self)
+      where(conditions)
+    end
+
     # Allows you to change a previously set where condition for a given attribute, instead of appending to that condition.
     #
     #   Post.where(trashed: true).where(trashed: false)
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index ef3338c0f8804..0c1aec5acd1fc 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -63,6 +63,16 @@ def test_multivalue_where
     assert_equal 1, posts.to_a.size
   end
 
+  def test_wharel
+    posts = Post.wharel { |post| post.author_id.not_eq(1).and(post.id.gt(2)) }
+    assert_equal 6, posts.to_a.size
+  end
+
+  def test_wharel_can_chain
+    posts = Post.wharel { |post| post.author_id.gteq(1) }.wharel { |post| post.id.lteq(4) }
+    assert_equal 3, posts.to_a.size
+  end
+
   def test_scoped
     topics = Topic.all
     assert_kind_of ActiveRecord::Relation, topics
@@ -514,6 +524,12 @@ def test_finding_with_hash_conditions_on_joined_table
     assert_equal companies(:rails_core), firms.first
   end
 
+  def tests_finding_with_block_on_joined_table
+    firms = DependentFirm.joins(:account).wharel { |firm| firm.name.eq("RailsCore").and(firm.accounts.credit_limit.in(55..60)) }.to_a
+    assert_equal 1, firms.size
+    assert_equal companies(:rails_core), firms.first
+  end
+
   def test_find_all_with_join
     developers_on_project_one = Developer.joins("LEFT JOIN developers_projects ON developers.id = developers_projects.developer_id").
       where("project_id=1").to_a