MONGOID-5037 use $pull instead of $pullAll for when documents change before destroying all (#5341)

* MONGOID-5037 use $pull instead of $pullAll for when documents change before destroying all

* MONGOID-5037 unpend test

* MONGOID-5037 sometimes use $pull sometimes use $pullAll

* MONGOID-5037 fix spacing

* MONGOID-5037 check base persisted before doing queries

* Update lib/mongoid/association/embedded/batchable.rb

* MONGOID-5037 remov extra check

Author: neilshweky

lib/mongoid/association/embedded/batchable.rb

@@ -50,20 +50,38 @@ def batch_clear(docs)
           _unscoped.clear
         end
 
-        # Batch remove the provided documents as a $pullAll.
+        # Batch remove the provided documents as a $pullAll or $pull.
         #
         # @example Batch remove the documents.
         #   batchable.batch_remove([ doc_one, doc_two ])
         #
         # @param [ Array<Document> ] docs The docs to remove.
         # @param [ Symbol ] method Delete or destroy.
         def batch_remove(docs, method = :delete)
+          # If the _id is nil, we cannot use $pull and delete by searching for
+          # the id. Therefore we have to use pullAll with the documents'
+          # attributes.
           removals = pre_process_batch_remove(docs, method)
+          pulls, pull_alls = removals.partition { |o| !o["_id"].nil? }
+
+          if !_base.persisted?
+            post_process_batch_remove(docs, method) unless docs.empty?
+            return reindex
+          end
+
           if !docs.empty?
-            collection.find(selector).update_one(
-              positionally(selector, "$pullAll" => { path => removals }),
-              session: _session
-            )
+            if !pulls.empty?
+              collection.find(selector).update_one(
+                positionally(selector, "$pull" => { path => { "_id" => { "$in" => pulls.pluck("_id") } } }),
+                session: _session
+              )
+            end
+            if !pull_alls.empty?
+              collection.find(selector).update_one(
+                positionally(selector, "$pullAll" => { path => pull_alls }),
+                session: _session
+              )
+            end
             post_process_batch_remove(docs, method)
           else
             collection.find(selector).update_one(

spec/integration/associations/embeds_many_spec.rb

@@ -172,8 +172,6 @@
           # Mongoid uses the new value of `x` in the $pullAll query,
           # which doesn't match the document that is in the database,
           # resulting in the empty array assignment not taking effect.
-          pending 'MONGOID-5037'
-
           canvas.shapes.first.x = 1
           canvas.shapes = []
           canvas.save!

spec/mongoid/association/embedded/embeds_many/proxy_spec.rb

@@ -2210,6 +2210,79 @@ class TrackingIdValidationHistory
           end
         end
       end
+
+      context "when modifying the document beforehand" do
+        let(:parent) { EmmParent.new }
+
+        before do
+
+          parent.blocks << EmmBlock.new(name: 'test', children: [size: 1, order: 1])
+          parent.save!
+
+          parent.blocks[0].children[0].assign_attributes(size: 2)
+
+          parent.blocks.destroy_all(:name => 'test')
+        end
+
+        it "deletes the correct document in the database" do
+          expect(parent.reload.blocks.length).to eq(0)
+        end
+      end
+
+      context "when nil _id" do
+        let(:parent) { EmmParent.new }
+
+        before do
+          parent.blocks << EmmBlock.new(_id: nil, name: 'test', children: [size: 1, order: 1])
+          parent.blocks << EmmBlock.new(_id: nil, name: 'test2', children: [size: 1, order: 1])
+          parent.save!
+
+          parent.blocks.destroy_all(:name => 'test')
+        end
+
+        it "deletes only the matching documents in the database" do
+          expect(parent.reload.blocks.length).to eq(1)
+        end
+      end
+
+      # Since without an _id field we must us a $pullAll with the attributes of
+      # the embedded document, if you modify it beforehand, the query will not
+      # be able to find the correct document to pull.
+      context "when modifying the document with nil _id" do
+        let(:parent) { EmmParent.new }
+
+        before do
+          parent.blocks << EmmBlock.new(_id: nil, name: 'test', children: [size: 1, order: 1])
+          parent.blocks << EmmBlock.new(_id: nil, name: 'test2', children: [size: 1, order: 1])
+          parent.save!
+
+          parent.blocks[0].children[0].assign_attributes(size: 2)
+
+          parent.blocks.destroy_all(:name => 'test')
+        end
+
+        it "does not delete the correct documents" do
+          expect(parent.reload.blocks.length).to eq(2)
+        end
+      end
+
+      context "when documents with and without _id" do
+        let(:parent) { EmmParent.new }
+
+        before do
+          parent.blocks << EmmBlock.new(_id: nil, name: 'test', children: [size: 1, order: 1])
+          parent.blocks << EmmBlock.new(name: 'test', children: [size: 1, order: 1])
+          parent.save!
+
+          parent.blocks[1].children[0].assign_attributes(size: 2)
+
+          parent.blocks.destroy_all(:name => 'test')
+        end
+
+        it "does not delete the correct documents" do
+          expect(parent.reload.blocks.length).to eq(0)
+        end
+      end
     end
   end
 

spec/mongoid/association/embedded/embeds_many_models.rb

@@ -203,3 +203,24 @@ class EmmStudent
 
   embedded_in :school, class_name: "EmmSchool"
 end
+
+class EmmParent
+  include Mongoid::Document
+  embeds_many :blocks, class_name: "EmmBlock"
+end
+
+class EmmBlock
+  include Mongoid::Document
+  field :name, type: String
+  embeds_many :children, class_name: "EmmChild"
+end
+
+class EmmChild
+  include Mongoid::Document
+  embedded_in :block, class_name: "EmmBlock"
+
+  field :size, type: Integer
+  field :order, type: Integer
+  field :t
+end
+