From ba0ae5fbd888652acf04ac360b9386313fab4af5 Mon Sep 17 00:00:00 2001
From: johnnyshields <johnny.shields@gmail.com>
Date: Fri, 21 Apr 2023 02:02:46 +0900
Subject: [PATCH 1/5] Fix exists on relations

---
 .../association/embedded/embeds_many/proxy.rb | 15 +++++++++++--
 .../association/referenced/has_many/proxy.rb  | 22 +------------------
 lib/mongoid/contextual/memory.rb              |  9 ++++++--
 lib/mongoid/contextual/mongo.rb               |  9 ++++++--
 lib/mongoid/contextual/none.rb                |  9 +++++---
 lib/mongoid/findable.rb                       |  9 ++++++--
 6 files changed, 41 insertions(+), 32 deletions(-)

diff --git a/lib/mongoid/association/embedded/embeds_many/proxy.rb b/lib/mongoid/association/embedded/embeds_many/proxy.rb
index ee2c38286..f511b8741 100644
--- a/lib/mongoid/association/embedded/embeds_many/proxy.rb
+++ b/lib/mongoid/association/embedded/embeds_many/proxy.rb
@@ -217,8 +217,19 @@ def destroy_all(conditions = {})
           # @example Are there persisted documents?
           #   person.posts.exists?
           #
-          # @param [ Hash | Object | false ] id_or_conditions an _id to
-          #   search for, a hash of conditions, nil or false.
+          # @example Is a document with the given id persisted?
+          #   context.exists?(BSON::ObjectId(...))
+          #
+          # @example Are there persisted documents with the given title?
+          #   person.posts.exists?({ title: "50 Ways to Leave Your Lover" })
+          #
+          # @example Always return false.
+          #   person.posts.exists?(false)
+          #
+          # @param [ :none | Hash | BSON::ObjectId | nil | false ] id_or_conditions
+          #   May optionally supply search conditions as a hash or an object id.
+          #   Will always return false when given nil or false. The symbol :none is
+          #   the default when argument is not supplied.
           #
           # @return [ true | false ] True is persisted documents exist, false if not.
           def exists?(id_or_conditions = :none)
diff --git a/lib/mongoid/association/referenced/has_many/proxy.rb b/lib/mongoid/association/referenced/has_many/proxy.rb
index 2be0615d8..021e609ea 100644
--- a/lib/mongoid/association/referenced/has_many/proxy.rb
+++ b/lib/mongoid/association/referenced/has_many/proxy.rb
@@ -14,7 +14,7 @@ class HasMany
         class Proxy < Association::Many
           extend Forwardable
 
-          def_delegator :criteria, :count
+          def_delegators :criteria, :count, :exists?
           def_delegators :_target, :first, :in_memory, :last, :reset, :uniq
 
           # Appends a document or array of documents to the association. Will set
@@ -163,26 +163,6 @@ def each(&block)
             end
           end
 
-          # Determine if any documents in this association exist in the database.
-          #
-          # If the association contains documents but all of the documents
-          # exist only in the application, i.e. have not been persisted to the
-          # database, this method returns false.
-          #
-          # This method queries the database on each invocation even if the
-          # association is already loaded into memory.
-          #
-          # @example Are there persisted documents?
-          #   person.posts.exists?
-          #
-          # @param [ Hash | Object | false ] id_or_conditions an _id to
-          #   search for, a hash of conditions, nil or false.
-          #
-          # @return [ true | false ] True is persisted documents exist, false if not.
-          def exists?(id_or_conditions = :none)
-            criteria.exists?(id_or_conditions)
-          end
-
           # Find the matching document on the association, either based on id or
           # conditions.
           #
diff --git a/lib/mongoid/contextual/memory.rb b/lib/mongoid/contextual/memory.rb
index 469851e12..2867a827e 100644
--- a/lib/mongoid/contextual/memory.rb
+++ b/lib/mongoid/contextual/memory.rb
@@ -116,8 +116,13 @@ def each(&block)
       # @example Do any documents exist for given conditions.
       #   context.exists?(name: "...")
       #
-      # @param [ Hash | Object | false ] id_or_conditions an _id to
-      #   search for, a hash of conditions, nil or false.
+      # @example Always return false.
+      #   context.exists?(false)
+      #
+      # @param [ :none | Hash | BSON::ObjectId | nil | false ] id_or_conditions
+      #   May optionally supply search conditions as a hash or an object id.
+      #   Will always return false when given nil or false. The symbol :none is
+      #   the default when argument is not supplied.
       #
       # @return [ true | false ] If the count is more than zero.
       #   Always false if passed nil or false.
diff --git a/lib/mongoid/contextual/mongo.rb b/lib/mongoid/contextual/mongo.rb
index c881f9c8e..49381aa4e 100644
--- a/lib/mongoid/contextual/mongo.rb
+++ b/lib/mongoid/contextual/mongo.rb
@@ -159,11 +159,16 @@ def each(&block)
       # @example Do any documents exist for given conditions.
       #   context.exists?(name: "...")
       #
+      # @example Always return false.
+      #   context.exists?(false)
+      #
       # @note We don't use count here since Mongo does not use counted
       #   b-tree indexes.
       #
-      # @param [ Hash | Object | false ] id_or_conditions an _id to
-      #   search for, a hash of conditions, nil or false.
+      # @param [ :none | Hash | BSON::ObjectId | nil | false ] id_or_conditions
+      #   May optionally supply search conditions as a hash or an object id.
+      #   Will always return false when given nil or false. The symbol :none is
+      #   the default when argument is not supplied.
       #
       # @return [ true | false ] If the count is more than zero.
       #   Always false if passed nil or false.
diff --git a/lib/mongoid/contextual/none.rb b/lib/mongoid/contextual/none.rb
index 6660f4c4a..cd9bd8208 100644
--- a/lib/mongoid/contextual/none.rb
+++ b/lib/mongoid/contextual/none.rb
@@ -57,7 +57,7 @@ def each(&block)
         end
       end
 
-      # Do any documents exist for the context.
+      # Do any documents exist for the null context.
       #
       # @example Do any documents exist in the null context.
       #   context.exists?
@@ -68,8 +68,11 @@ def each(&block)
       # @example Do any documents exist for given conditions.
       #   context.exists?(name: "...")
       #
-      # @param [ Hash | Object | false ] _id_or_conditions An _id to
-      #   search for, a hash of conditions, nil or false.
+      # @example Always return false.
+      #   context.exists?(false)
+      #
+      # @param [ :none | Hash | BSON::ObjectId | nil | false ] _id_or_conditions
+      #   Not used in null context.
       #
       # @return [ false ] Always false.
       def exists?(_id_or_conditions = :none)
diff --git a/lib/mongoid/findable.rb b/lib/mongoid/findable.rb
index a29a47bc9..cf6c4fa3e 100644
--- a/lib/mongoid/findable.rb
+++ b/lib/mongoid/findable.rb
@@ -107,8 +107,13 @@ def empty?
     # @example Do any documents exist for given conditions.
     #   Person.exists?(name: "...")
     #
-    # @param [ Hash | Object | false ] id_or_conditions an _id to
-    #   search for, a hash of conditions, nil or false.
+    # @example Always return false.
+    #   context.exists?(false)
+    #
+    # @param [ :none | Hash | BSON::ObjectId | nil | false ] id_or_conditions
+    #   May optionally supply search conditions as a hash or an object id.
+    #   Will always return false when given nil or false. The symbol :none is
+    #   the default when argument is not supplied.
     #
     # @return [ true | false ] If any documents exist for the conditions.
     #   Always false if passed nil or false.

From 09aadde060910ee7aaa25ee83010b1dc77ac55a8 Mon Sep 17 00:00:00 2001
From: johnnyshields <johnny.shields@gmail.com>
Date: Fri, 21 Apr 2023 16:25:40 +0900
Subject: [PATCH 2/5] Fix MONGOID-5610

---
 docs/release-notes/mongoid-9.0.txt            |   6 +
 .../association/embedded/embeds_many/proxy.rb |  28 +--
 lib/mongoid/contextual/memory.rb              |   2 +-
 .../embedded/embeds_many/proxy_spec.rb        | 220 +++++++++++++++++-
 4 files changed, 219 insertions(+), 37 deletions(-)

diff --git a/docs/release-notes/mongoid-9.0.txt b/docs/release-notes/mongoid-9.0.txt
index 5e52492af..b9c1c53f9 100644
--- a/docs/release-notes/mongoid-9.0.txt
+++ b/docs/release-notes/mongoid-9.0.txt
@@ -370,6 +370,12 @@ Bug Fixes and Improvements
 
 This section will be for smaller bug fixes and improvements:
 
+- The ``exists?`` method on relations now accepts the same arguments
+  as ``Criteria#exists?``.
+  `MONGOID-5608 <https://jira.mongodb.org/browse/MONGOID-5608>`_.
+- Calling ``exists?`` on an embedded relation nil now return ``false``
+  when the relation is not persisted in the database.
+  `MONGOID-5610 <https://jira.mongodb.org/browse/MONGOID-5610>`_.
 - The ``.tally`` method can now take a keyword arg :unwind
   which tallies array values individually (using the ``$unwind`` operator.)
   `MONGOID-5556 <https://jira.mongodb.org/browse/MONGOID-5556>`_.
diff --git a/lib/mongoid/association/embedded/embeds_many/proxy.rb b/lib/mongoid/association/embedded/embeds_many/proxy.rb
index f511b8741..2dd8c00ed 100644
--- a/lib/mongoid/association/embedded/embeds_many/proxy.rb
+++ b/lib/mongoid/association/embedded/embeds_many/proxy.rb
@@ -16,6 +16,8 @@ class EmbedsMany
         class Proxy < Association::Many
           include Batchable
 
+          def_delegator :criteria, :exists?
+
           # Appends a document or array of documents to the association. Will set
           # the parent and update the index in the process.
           #
@@ -212,32 +214,6 @@ def destroy_all(conditions = {})
             remove_all(conditions, :destroy)
           end
 
-          # Determine if any documents in this association exist in the database.
-          #
-          # @example Are there persisted documents?
-          #   person.posts.exists?
-          #
-          # @example Is a document with the given id persisted?
-          #   context.exists?(BSON::ObjectId(...))
-          #
-          # @example Are there persisted documents with the given title?
-          #   person.posts.exists?({ title: "50 Ways to Leave Your Lover" })
-          #
-          # @example Always return false.
-          #   person.posts.exists?(false)
-          #
-          # @param [ :none | Hash | BSON::ObjectId | nil | false ] id_or_conditions
-          #   May optionally supply search conditions as a hash or an object id.
-          #   Will always return false when given nil or false. The symbol :none is
-          #   the default when argument is not supplied.
-          #
-          # @return [ true | false ] True is persisted documents exist, false if not.
-          def exists?(id_or_conditions = :none)
-            return _target.any?(&:persisted?) if id_or_conditions == :none
-
-            criteria.exists?(id_or_conditions)
-          end
-
           # Finds a document in this association through several different
           # methods.
           #
diff --git a/lib/mongoid/contextual/memory.rb b/lib/mongoid/contextual/memory.rb
index 2867a827e..44d59ec14 100644
--- a/lib/mongoid/contextual/memory.rb
+++ b/lib/mongoid/contextual/memory.rb
@@ -128,7 +128,7 @@ def each(&block)
       #   Always false if passed nil or false.
       def exists?(id_or_conditions = :none)
         case id_or_conditions
-        when :none then any?
+        when :none then any?(&:persisted?)
         when nil, false then false
         when Hash then Memory.new(criteria.where(id_or_conditions)).exists?
         else Memory.new(criteria.where(_id: id_or_conditions)).exists?
diff --git a/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb b/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb
index 2c62d13e9..2914d5ded 100644
--- a/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb
+++ b/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb
@@ -2294,29 +2294,229 @@ class TrackingIdValidationHistory
 
   describe '#exists?' do
 
-    let!(:person) do
+    let!(:person1) do
       Person.create!
     end
 
-    context 'when documents exist in the database' do
+    let!(:person2) do
+      Person.create!
+    end
 
-      before do
-        person.addresses.create!(street: 'Bond St')
+    let!(:person3) do
+      Person.new
+    end
+
+    let!(:address1_1) do
+      person1.addresses.create!(street: 'Bond St')
+    end
+
+    let!(:address1_2) do
+      person1.addresses.build(street: 'Hyde Park Dr')
+    end
+
+    let!(:address2) do
+      person2.addresses.build(street: 'Hyde Park Dr')
+    end
+
+    let!(:address3) do
+      person3.addresses.build(street: 'Hyde Park Dr')
+    end
+
+    context 'when not passing args' do
+
+      context 'when documents exist in the database' do
+
+        it 'returns true' do
+          expect_no_queries do
+            expect(person1.addresses.exists?).to be true
+          end
+        end
       end
 
-      it 'returns true' do
-        expect(person.addresses.exists?).to be true
+      context 'when no documents exist in the database' do
+
+        it 'returns false' do
+          expect_no_queries do
+            expect(person2.addresses.exists?).to be false
+          end
+        end
+      end
+
+      context 'when parent object not persisted' do
+
+        it 'returns false' do
+          expect_no_queries do
+            expect(person3.addresses.exists?).to be false
+          end
+        end
       end
     end
 
-    context 'when no documents exist in the database' do
+    context 'when passing :none' do
 
-      before do
-        person.addresses.build(street: 'Hyde Park Dr')
+      context 'when documents exist in the database' do
+
+        it 'returns true' do
+          expect_no_queries do
+            expect(person1.addresses.exists?(:none)).to be true
+          end
+        end
+      end
+
+      context 'when no documents exist in the database' do
+
+        it 'returns false' do
+          expect_no_queries do
+            expect(person2.addresses.exists?(:none)).to be false
+          end
+        end
       end
+    end
+
+    context 'when passing an _id' do
+
+      context 'when its of type BSON::ObjectId' do
+
+        context 'when embedded object persisted' do
+
+          it 'returns true' do
+            expect_no_queries do
+              expect(person1.addresses.exists?(address1_1._id)).to be true
+            end
+          end
+        end
+
+        context 'when embedded object not persisted' do
+
+          it 'returns false' do
+            expect_no_queries do
+              expect(person1.addresses.exists?(address1_2._id)).to be false
+            end
+          end
+        end
+
+        context 'when parent object not persisted' do
+
+          it 'returns false' do
+            expect_no_queries do
+              expect(person3.addresses.exists?(address3._id)).to be false
+            end
+          end
+        end
+
+        context 'when the id does not exist' do
+
+          it 'returns false' do
+            expect_no_queries do
+              expect(person1.addresses.exists?(BSON::ObjectId.new)).to be false
+            end
+          end
+        end
+      end
+
+      context 'when its of type String' do
+
+        context 'when embedded object persisted' do
+
+          it 'returns true' do
+            expect_no_queries do
+              expect(person1.addresses.exists?(address1_1._id.to_s)).to be true
+            end
+          end
+        end
+
+        context 'when embedded object not persisted' do
+
+          it 'returns false' do
+            expect_no_queries do
+              expect(person1.addresses.exists?(address1_2._id.to_s)).to be false
+            end
+          end
+        end
+
+        context 'when parent object not persisted' do
+
+          it 'returns false' do
+            expect_no_queries do
+              expect(person3.addresses.exists?(address3._id.to_s)).to be false
+            end
+          end
+        end
+
+        context 'when the id does not exist' do
+
+          it 'returns false' do
+            expect_no_queries do
+              expect(person1.addresses.exists?(BSON::ObjectId.new.to_s)).to be false
+            end
+          end
+        end
+      end
+    end
+
+    context 'when passing a hash' do
+
+      context 'when embedded object persisted' do
+
+        it 'returns true' do
+          expect_no_queries do
+            expect(person1.addresses.exists?(street: address1_1.street)).to be true
+          end
+        end
+      end
+
+      context 'when embedded object not persisted' do
+
+        it 'returns false' do
+          expect_no_queries do
+            expect(person1.addresses.exists?(street: address1_2.street)).to be false
+          end
+        end
+      end
+
+      context 'when parent object not persisted' do
+
+        it 'returns false' do
+          expect_no_queries do
+            expect(person3.addresses.exists?(street: address3.street)).to be false
+          end
+        end
+      end
+
+      context 'when the value does not exist' do
+
+        it 'returns false' do
+          expect_no_queries do
+            expect(person1.addresses.exists?(street: 'Foobar')).to be false
+          end
+        end
+      end
+    end
+
+    context 'when passing false' do
+
+      it 'returns false' do
+        expect_no_queries do
+          expect(person1.addresses.exists?(false)).to be false
+        end
+      end
+    end
+
+    context 'when passing nil' do
 
       it 'returns false' do
-        expect(person.addresses.exists?).to be false
+        expect_no_queries do
+          expect(person1.addresses.exists?(nil)).to be false
+        end
+      end
+    end
+
+    context 'when the limit is 0' do
+
+      it 'returns false' do
+        expect_no_queries do
+          expect(person1.addresses.limit(0).exists?).to be false
+        end
       end
     end
   end

From b1579e8255e731aeedbf256101163d90bd96857f Mon Sep 17 00:00:00 2001
From: johnnyshields <johnny.shields@gmail.com>
Date: Fri, 21 Apr 2023 16:30:27 +0900
Subject: [PATCH 3/5] Fix rubocop

---
 .../embedded/embeds_many/proxy_spec.rb           | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb b/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb
index 2914d5ded..d795edd2b 100644
--- a/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb
+++ b/spec/mongoid/association/embedded/embeds_many/proxy_spec.rb
@@ -2306,11 +2306,11 @@ class TrackingIdValidationHistory
       Person.new
     end
 
-    let!(:address1_1) do
+    let!(:address1_persisted) do
       person1.addresses.create!(street: 'Bond St')
     end
 
-    let!(:address1_2) do
+    let!(:address1_not_persisted) do
       person1.addresses.build(street: 'Hyde Park Dr')
     end
 
@@ -2381,7 +2381,7 @@ class TrackingIdValidationHistory
 
           it 'returns true' do
             expect_no_queries do
-              expect(person1.addresses.exists?(address1_1._id)).to be true
+              expect(person1.addresses.exists?(address1_persisted._id)).to be true
             end
           end
         end
@@ -2390,7 +2390,7 @@ class TrackingIdValidationHistory
 
           it 'returns false' do
             expect_no_queries do
-              expect(person1.addresses.exists?(address1_2._id)).to be false
+              expect(person1.addresses.exists?(address1_not_persisted._id)).to be false
             end
           end
         end
@@ -2420,7 +2420,7 @@ class TrackingIdValidationHistory
 
           it 'returns true' do
             expect_no_queries do
-              expect(person1.addresses.exists?(address1_1._id.to_s)).to be true
+              expect(person1.addresses.exists?(address1_persisted._id.to_s)).to be true
             end
           end
         end
@@ -2429,7 +2429,7 @@ class TrackingIdValidationHistory
 
           it 'returns false' do
             expect_no_queries do
-              expect(person1.addresses.exists?(address1_2._id.to_s)).to be false
+              expect(person1.addresses.exists?(address1_not_persisted._id.to_s)).to be false
             end
           end
         end
@@ -2460,7 +2460,7 @@ class TrackingIdValidationHistory
 
         it 'returns true' do
           expect_no_queries do
-            expect(person1.addresses.exists?(street: address1_1.street)).to be true
+            expect(person1.addresses.exists?(street: address1_persisted.street)).to be true
           end
         end
       end
@@ -2469,7 +2469,7 @@ class TrackingIdValidationHistory
 
         it 'returns false' do
           expect_no_queries do
-            expect(person1.addresses.exists?(street: address1_2.street)).to be false
+            expect(person1.addresses.exists?(street: address1_not_persisted.street)).to be false
           end
         end
       end

From 95a92ebc506b778b3391d8a2018fd208a4a1e809 Mon Sep 17 00:00:00 2001
From: johnnyshields <johnny.shields@gmail.com>
Date: Fri, 21 Apr 2023 18:30:55 +0900
Subject: [PATCH 4/5] Fix exists?

---
 lib/mongoid/contextual/memory.rb | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/mongoid/contextual/memory.rb b/lib/mongoid/contextual/memory.rb
index 44d59ec14..24868e17d 100644
--- a/lib/mongoid/contextual/memory.rb
+++ b/lib/mongoid/contextual/memory.rb
@@ -105,6 +105,17 @@ def each(&block)
         end
       end
 
+      # Is the enumerable of matching documents empty?
+      #
+      # @example Is the context empty?
+      #   context.blank?
+      #
+      # @return [ true | false ] If the context is empty.
+      def blank?
+        !any?
+      end
+      alias_method :empty?, :blank?
+
       # Do any documents exist for the context.
       #
       # @example Do any documents exist for the context.

From 069dc61ddc1d8ac6cf1a7fbf7892029e52dbbbcd Mon Sep 17 00:00:00 2001
From: johnnyshields <johnny.shields@gmail.com>
Date: Fri, 21 Apr 2023 18:32:21 +0900
Subject: [PATCH 5/5] blank? should use any?

---
 lib/mongoid/contextual/memory.rb    | 11 -----------
 lib/mongoid/contextual/queryable.rb |  2 +-
 2 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/lib/mongoid/contextual/memory.rb b/lib/mongoid/contextual/memory.rb
index 24868e17d..44d59ec14 100644
--- a/lib/mongoid/contextual/memory.rb
+++ b/lib/mongoid/contextual/memory.rb
@@ -105,17 +105,6 @@ def each(&block)
         end
       end
 
-      # Is the enumerable of matching documents empty?
-      #
-      # @example Is the context empty?
-      #   context.blank?
-      #
-      # @return [ true | false ] If the context is empty.
-      def blank?
-        !any?
-      end
-      alias_method :empty?, :blank?
-
       # Do any documents exist for the context.
       #
       # @example Do any documents exist for the context.
diff --git a/lib/mongoid/contextual/queryable.rb b/lib/mongoid/contextual/queryable.rb
index e97965d26..436828e49 100644
--- a/lib/mongoid/contextual/queryable.rb
+++ b/lib/mongoid/contextual/queryable.rb
@@ -19,7 +19,7 @@ module Queryable
       #
       # @return [ true | false ] If the context is empty.
       def blank?
-        !exists?
+        !any?
       end
       alias_method :empty?, :blank?
     end