Merge Pull Request #16052 Added #or to ActiveRecord::Relation

8 files changed, 166 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index c0ebb892aa..73dfc1d647 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,13 @@
+*   Added the `#or` method on ActiveRecord::Relation, allowing use of the OR
+    operator to combine WHERE or HAVING clauses.
+
+    Example:
+
+        Post.where('id = 1').or(Post.where('id = 2'))
+        # => SELECT * FROM posts WHERE (id = 1) OR (id = 2)
+
+    *Sean Griffin*, *Matthew Draper*, *Gael Muller*, *Olivier El Mekki*
+
 *   Don't define autosave association callbacks twice from
     `accepts_nested_attributes_for`.
 
diff --git a/activerecord/lib/active_record/null_relation.rb b/activerecord/lib/active_record/null_relation.rb
index b406da14dc..63ca29305d 100644
--- a/activerecord/lib/active_record/null_relation.rb
+++ b/activerecord/lib/active_record/null_relation.rb
@@ -75,5 +75,9 @@ module ActiveRecord
     def exists?(_id = false)
       false
     end
+
+    def or(other)
+      other.spawn
+    end
   end
 end
diff --git a/activerecord/lib/active_record/querying.rb b/activerecord/lib/active_record/querying.rb
index 91c9a0db99..4e597590e9 100644
--- a/activerecord/lib/active_record/querying.rb
+++ b/activerecord/lib/active_record/querying.rb
@@ -7,7 +7,7 @@ module ActiveRecord
     delegate :find_by, :find_by!, to: :all
     delegate :destroy, :destroy_all, :delete, :delete_all, :update, :update_all, to: :all
     delegate :find_each, :find_in_batches, to: :all
-    delegate :select, :group, :order, :except, :reorder, :limit, :offset, :joins,
+    delegate :select, :group, :order, :except, :reorder, :limit, :offset, :joins, :or,
              :where, :rewhere, :preload, :eager_load, :includes, :from, :lock, :readonly,
              :having, :create_with, :uniq, :distinct, :references, :none, :unscope, to: :all
     delegate :count, :average, :minimum, :maximum, :sum, :calculate, to: :all
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 0078b0f32e..b0edb3b1f2 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -582,6 +582,37 @@ module ActiveRecord
       unscope(where: conditions.keys).where(conditions)
     end
 
+    # Returns a new relation, which is the logical union of this relation and the one passed as an
+    # argument.
+    #
+    # The two relations must be structurally compatible: they must be scoping the same model, and
+    # they must differ only by +where+ (if no +group+ has been defined) or +having+ (if a +group+ is
+    # present). Neither relation may have a +limit+, +offset+, or +uniq+ set.
+    #
+    #    Post.where("id = 1").or(Post.where("id = 2"))
+    #    # SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))
+    #
+    def or(other)
+      spawn.or!(other)
+    end
+
+    def or!(other) # :nodoc:
+      unless structurally_compatible_for_or?(other)
+        raise ArgumentError, 'Relation passed to #or must be structurally compatible'
+      end
+
+      self.where_clause = self.where_clause.or(other.where_clause)
+      self.having_clause = self.having_clause.or(other.having_clause)
+
+      self
+    end
+
+    private def structurally_compatible_for_or?(other) # :nodoc:
+      Relation::SINGLE_VALUE_METHODS.all? { |m| send("#{m}_value") == other.send("#{m}_value") } &&
+        (Relation::MULTI_VALUE_METHODS - [:extending]).all? { |m| send("#{m}_values") == other.send("#{m}_values") } &&
+        (Relation::CLAUSE_METHODS - [:having, :where]).all? { |m| send("#{m}_clause") != other.send("#{m}_clause") }
+    end
+
     # Allows to specify a HAVING clause. Note that you can't use HAVING
     # without also specifying a GROUP clause.
     #
diff --git a/activerecord/lib/active_record/relation/where_clause.rb b/activerecord/lib/active_record/relation/where_clause.rb
index ae5667dfd6..ce307e4f0c 100644
--- a/activerecord/lib/active_record/relation/where_clause.rb
+++ b/activerecord/lib/active_record/relation/where_clause.rb
@@ -31,6 +31,19 @@ module ActiveRecord
         )
       end
 
+      def or(other)
+        if empty?
+          other
+        elsif other.empty?
+          self
+        else
+          WhereClause.new(
+            [ast.or(other.ast)],
+            binds + other.binds
+          )
+        end
+      end
+
       def to_h(table_name = nil)
         equalities = predicates.grep(Arel::Nodes::Equality)
         if table_name
diff --git a/activerecord/test/cases/relation/or_test.rb b/activerecord/test/cases/relation/or_test.rb
new file mode 100644
index 0000000000..1515b9c454
--- /dev/null
+++ b/activerecord/test/cases/relation/or_test.rb
@@ -0,0 +1,84 @@
+require "cases/helper"
+require 'models/post'
+
+module ActiveRecord
+  class OrTest < ActiveRecord::TestCase
+    fixtures :posts
+
+    def test_or_with_relation
+      expected = Post.where('id = 1 or id = 2').to_a
+      assert_equal expected, Post.where('id = 1').or(Post.where('id = 2')).to_a
+    end
+
+    def test_or_identity
+      expected = Post.where('id = 1').to_a
+      assert_equal expected, Post.where('id = 1').or(Post.where('id = 1')).to_a
+    end
+
+    def test_or_with_null_left
+      expected = Post.where('id = 1').to_a
+      assert_equal expected, Post.none.or(Post.where('id = 1')).to_a
+    end
+
+    def test_or_with_null_right
+      expected = Post.where('id = 1').to_a
+      assert_equal expected, Post.where('id = 1').or(Post.none).to_a
+    end
+
+    def test_or_with_bind_params
+      assert_equal Post.find([1, 2]), Post.where(id: 1).or(Post.where(id: 2)).to_a
+    end
+
+    def test_or_with_null_both
+      expected = Post.none.to_a
+      assert_equal expected, Post.none.or(Post.none).to_a
+    end
+
+    def test_or_without_left_where
+      expected = Post.where('id = 1')
+      assert_equal expected, Post.or(Post.where('id = 1')).to_a
+    end
+
+    def test_or_without_right_where
+      expected = Post.where('id = 1')
+      assert_equal expected, Post.where('id = 1').or(Post.all).to_a
+    end
+
+    def test_or_preserves_other_querying_methods
+      expected = Post.where('id = 1 or id = 2 or id = 3').order('body asc').to_a
+      partial = Post.order('body asc')
+      assert_equal expected, partial.where('id = 1').or(partial.where(:id => [2, 3])).to_a
+      assert_equal expected, Post.order('body asc').where('id = 1').or(Post.order('body asc').where(:id => [2, 3])).to_a
+    end
+
+    def test_or_with_incompatible_relations
+      assert_raises ArgumentError do
+        Post.order('body asc').where('id = 1').or(Post.order('id desc').where(:id => [2, 3])).to_a
+      end
+    end
+
+    def test_or_when_grouping
+      groups = Post.where('id < 10').group('body').select('body, COUNT(*) AS c')
+      expected = groups.having("COUNT(*) > 1 OR body like 'Such%'").to_a.map {|o| [o.body, o.c] }
+      assert_equal expected, groups.having('COUNT(*) > 1').or(groups.having("body like 'Such%'")).to_a.map {|o| [o.body, o.c] }
+    end
+
+    def test_or_with_named_scope
+      expected = Post.where("id = 1 or body LIKE '\%a\%'").to_a
+      assert_equal expected, Post.where('id = 1').or(Post.containing_the_letter_a)
+    end
+
+    def test_or_inside_named_scope
+      expected = Post.where("body LIKE '\%a\%' OR title LIKE ?", "%'%").order('id DESC').to_a
+      assert_equal expected, Post.order(id: :desc).typographically_interesting
+    end
+
+    def test_or_on_loaded_relation
+      expected = Post.where('id = 1 or id = 2').to_a
+      p = Post.where('id = 1')
+      p.load
+      assert_equal p.loaded?, true
+      assert_equal expected, p.or(Post.where('id = 2')).to_a
+    end
+  end
+end
diff --git a/activerecord/test/cases/relation/where_clause_test.rb b/activerecord/test/cases/relation/where_clause_test.rb
index db18980e0b..7325aec0a9 100644
--- a/activerecord/test/cases/relation/where_clause_test.rb
+++ b/activerecord/test/cases/relation/where_clause_test.rb
@@ -145,6 +145,26 @@ class ActiveRecord::Relation
       assert_equal where_clause.ast, where_clause_with_empty.ast
     end
 
+    test "or joins the two clauses using OR" do
+      where_clause = WhereClause.new([table["id"].eq(bind_param)], [attribute("id", 1)])
+      other_clause = WhereClause.new([table["name"].eq(bind_param)], [attribute("name", "Sean")])
+      expected_ast =
+        Arel::Nodes::Grouping.new(
+          Arel::Nodes::Or.new(table["id"].eq(bind_param), table["name"].eq(bind_param))
+        )
+      expected_binds = where_clause.binds + other_clause.binds
+
+      assert_equal expected_ast.to_sql, where_clause.or(other_clause).ast.to_sql
+      assert_equal expected_binds, where_clause.or(other_clause).binds
+    end
+
+    test "or does nothing with an empty where clause" do
+      where_clause = WhereClause.new([table["id"].eq(bind_param)], [attribute("id", 1)])
+
+      assert_equal where_clause, where_clause.or(WhereClause.empty)
+      assert_equal where_clause, WhereClause.empty.or(where_clause)
+    end
+
     private
 
     def table
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index 7b637c9e3f..052b1c9690 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -18,6 +18,7 @@ class Post < ActiveRecord::Base
   end
 
   scope :containing_the_letter_a, -> { where("body LIKE '%a%'") }
+  scope :titled_with_an_apostrophe, -> { where("title LIKE '%''%'") }
   scope :ranked_by_comments,      -> { order("comments_count DESC") }
 
   scope :limit_by, lambda {|l| limit(l) }
@@ -43,6 +44,8 @@ class Post < ActiveRecord::Base
   scope :tagged_with, ->(id) { joins(:taggings).where(taggings: { tag_id: id }) }
   scope :tagged_with_comment, ->(comment) { joins(:taggings).where(taggings: { comment: comment }) }
 
+  scope :typographically_interesting, -> { containing_the_letter_a.or(titled_with_an_apostrophe) }
+
   has_many   :comments do
     def find_most_recent
       order("id DESC").first