From 903128c312169dff9fac3649a00c19a4f6b2c70e Mon Sep 17 00:00:00 2001
From: DarshanaVenkatesh <70602567+DarshanaVenkatesh@users.noreply.github.com>
Date: Fri, 13 Dec 2024 09:57:55 -0800
Subject: [PATCH] MONGOID-5780 Fix chaining nots resulting in incorrect
 negation state (backport to 9.0)

---
 lib/mongoid/criteria/queryable/selectable.rb  |  2 +-
 .../criteria/queryable/selectable_spec.rb     | 29 +++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/lib/mongoid/criteria/queryable/selectable.rb b/lib/mongoid/criteria/queryable/selectable.rb
index 3a4373baa4..2d308a09bd 100644
--- a/lib/mongoid/criteria/queryable/selectable.rb
+++ b/lib/mongoid/criteria/queryable/selectable.rb
@@ -553,7 +553,7 @@ def negating?
         # @return [ Selectable ] The new selectable.
         def not(*criteria)
           if criteria.empty?
-            dup.tap { |query| query.negating = true }
+            dup.tap { |query| query.negating = !query.negating }
           else
             criteria.compact.inject(self.clone) do |c, new_s|
               if new_s.is_a?(Selectable)
diff --git a/spec/mongoid/criteria/queryable/selectable_spec.rb b/spec/mongoid/criteria/queryable/selectable_spec.rb
index 59159f925f..9cc4b2443a 100644
--- a/spec/mongoid/criteria/queryable/selectable_spec.rb
+++ b/spec/mongoid/criteria/queryable/selectable_spec.rb
@@ -1939,6 +1939,35 @@ def localized?
     end
   end
 
+  describe "#not" do
+    context "when negating a criterion" do
+      let(:selection) do
+        query.not(field: /value/)
+      end
+
+      it "adds the $not selector" do
+        expect(selection.selector).to eq({
+          "field" => { "$not" => /value/ }
+        })
+      end
+
+      it "returns a cloned query" do
+        expect(selection).to_not equal(query)
+      end
+
+      context "when toggling negation state" do
+        it "negates the negating value" do
+          expect(query.negating).to be_nil 
+          negated_query = query.not
+          expect(negated_query.negating).to be true
+          double_negated_query = negated_query.not
+          expect(double_negated_query.negating).to be false
+        end
+      end
+    end
+  end
+
+
   describe Symbol do
 
     describe "#all" do