MONGOID-5653 - Move Hash#__nested__ monkey patch method to new module Mongoid::Attributes::Embedded.traverse (#5692)

* Move Hash#__nested__ monkey patch method to new module Mongoid::Attributes::Embedded.traverse

* Fix whitespace

* Fix rubocop whitespace warning

* Update embedded.rb

* minor changes to test names

---------

Co-authored-by: Jamis Buck <[email protected]>

Author: johnnyshields

lib/mongoid/attributes.rb

@@ -3,6 +3,7 @@
 
 require "active_model/attribute_methods"
 require "mongoid/attributes/dynamic"
+require "mongoid/attributes/embedded"
 require "mongoid/attributes/nested"
 require "mongoid/attributes/processing"
 require "mongoid/attributes/projector"
@@ -299,7 +300,7 @@ def read_raw_attribute(name)
         if fields.key?(normalized)
           attributes[normalized]
         else
-          attributes.__nested__(normalized)
+          Embedded.traverse(attributes, normalized)
         end
       else
         attributes[normalized]

lib/mongoid/attributes/embedded.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Mongoid
+  module Attributes
+    # Utility module for working with embedded attributes.
+    module Embedded
+      extend self
+
+      # Fetch an embedded value or subset of attributes via dot notation.
+      #
+      # @example Fetch an embedded value via dot notation.
+      #   Embedded.traverse({ 'name' => { 'en' => 'test' } }, 'name.en')
+      #   #=> 'test'
+      #
+      # @param [ Hash ] attributes The document attributes.
+      # @param [ String ] path The dot notation string.
+      #
+      # @return [ Object | nil ] The attributes at the given path,
+      #   or nil if the path doesn't exist.
+      def traverse(attributes, path)
+        path.split('.').each do |key|
+          break if attributes.nil?
+
+          attributes = if attributes.try(:key?, key)
+                         attributes[key]
+                       elsif attributes.respond_to?(:each) && key.match?(/\A\d+\z/)
+                         attributes[key.to_i]
+                       end
+        end
+        attributes
+      end
+    end
+  end
+end

lib/mongoid/attributes/nested.rb

@@ -4,7 +4,7 @@
 module Mongoid
   module Attributes
 
-    # Defines behavior around that lovel Rails feature nested attributes.
+    # Defines behavior for the Rails nested attributes feature.
     module Nested
       extend ActiveSupport::Concern
 

lib/mongoid/extensions/hash.rb

@@ -127,28 +127,6 @@ def extract_id
         self["_id"] || self[:_id] || self["id"] || self[:id]
       end
 
-      # Fetch a nested value via dot syntax.
-      #
-      # @example Fetch a nested value via dot syntax.
-      #   { "name" => { "en" => "test" }}.__nested__("name.en")
-      #
-      # @param [ String ] string the dot syntax string.
-      #
-      # @return [ Object ] The matching value.
-      def __nested__(string)
-        keys = string.split(".")
-        value = self
-        keys.each do |key|
-          return nil if value.nil?
-          value_for_key = value[key]
-          if value_for_key.nil? && key.to_i.to_s == key
-            value_for_key = value[key.to_i]
-          end
-          value = value_for_key
-        end
-        value
-      end
-
       # Turn the object from the ruby type we deal with to a Mongo friendly
       # type.
       #

lib/mongoid/reloadable.rb

@@ -91,26 +91,10 @@ def reload_root_document
     #
     # @return [ Hash ] The reloaded attributes.
     def reload_embedded_document
-      extract_embedded_attributes(
-        collection(_root).find(_root.atomic_selector, session: _session).read(mode: :primary).first
+      Mongoid::Attributes::Embedded.traverse(
+        collection(_root).find(_root.atomic_selector, session: _session).read(mode: :primary).first,
+        atomic_position
       )
     end
-
-    # Extract only the desired embedded document from the attributes.
-    #
-    # @example Extract the embedded document.
-    #   document.extract_embedded_attributes(attributes)
-    #
-    # @param [ Hash ] attributes The document in the db.
-    #
-    # @return [ Hash | nil ] The document's extracted attributes or nil if the
-    #   document doesn't exist.
-    def extract_embedded_attributes(attributes)
-      # rubocop:disable Lint/UnmodifiedReduceAccumulator
-      atomic_position.split('.').inject(attributes) do |attrs, part|
-        attrs[Utils.maybe_integer(part)]
-      end
-      # rubocop:enable Lint/UnmodifiedReduceAccumulator
-    end
   end
 end

lib/mongoid/utils.rb

@@ -22,20 +22,6 @@ def placeholder?(value)
       value == PLACEHOLDER
     end
 
-    # If value can be coerced to an integer, return it as an integer.
-    # Otherwise, return the value itself.
-    #
-    # @param [ String ] value the string to possibly coerce.
-    #
-    # @return [ String | Integer ] the result of the coercion.
-    def maybe_integer(value)
-      if value.match?(/^\d/)
-        value.to_i
-      else
-        value
-      end
-    end
-
     # This function should be used if you need to measure time.
     # @example Calculate elapsed time.
     #   starting = Utils.monotonic_time

spec/mongoid/attributes/embedded_spec.rb

@@ -0,0 +1,118 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Mongoid::Attributes::Embedded do
+  describe '.traverse' do
+    subject(:embedded) { described_class.traverse(attributes, path) }
+
+    let(:path) { '100.name' }
+
+    context 'when the attribute key is a string' do
+      let(:attributes) { { '100' => { 'name' => 'hundred' } } }
+
+      it 'retrieves an embedded value under the provided key' do
+        expect(embedded).to eq 'hundred'
+      end
+
+      context 'when the value is false' do
+        let(:attributes) { { '100' => { 'name' => false } } }
+
+        it 'retrieves the embedded value under the provided key' do
+          expect(embedded).to be false
+        end
+      end
+
+      context 'when the value does not exist' do
+        let(:attributes) { { '100' => { 0 => 'Please do not return this value!' } } }
+
+        it 'returns nil' do
+          expect(embedded).to be_nil
+        end
+      end
+    end
+
+    context 'when the attribute key is an integer' do
+      let(:attributes) { { 100 => { 'name' => 'hundred' } } }
+
+      it 'retrieves an embedded value under the provided key' do
+        expect(embedded).to eq 'hundred'
+      end
+    end
+
+    context 'when the attribute value is nil' do
+      let(:attributes) { { 100 => { 'name' => nil } } }
+
+      it 'returns nil' do
+        expect(embedded).to be_nil
+      end
+    end
+
+    context 'when both string and integer keys are present' do
+      let(:attributes) { { '100' => { 'name' => 'Fred' }, 100 => { 'name' => 'Daphne' } } }
+
+      it 'returns the string key value' do
+        expect(embedded).to eq 'Fred'
+      end
+
+      context 'when the string key value is nil' do
+        let(:attributes) { { '100' => nil, 100 => { 'name' => 'Daphne' } } }
+
+        it 'returns nil' do
+          expect(embedded).to be_nil
+        end
+      end
+    end
+
+    context 'when attributes is an array' do
+      let(:attributes) do
+        [ { 'name' => 'Fred' }, { 'name' => 'Daphne' }, { 'name' => 'Velma' }, { 'name' => 'Shaggy' } ]
+      end
+      let(:path) { '2.name' }
+
+      it 'retrieves the nth value' do
+        expect(embedded).to eq 'Velma'
+      end
+
+      context 'when the member does not exist' do
+        let(:attributes) { [ { 'name' => 'Fred' }, { 'name' => 'Daphne' } ] }
+
+        it 'returns nil' do
+          expect(embedded).to be_nil
+        end
+      end
+    end
+
+    context 'when the path includes a scalar value' do
+      let(:attributes) { { '100' => 'name' } }
+
+      it 'returns nil' do
+        expect(embedded).to be_nil
+      end
+    end
+
+    context 'when the parent key is not present' do
+      let(:attributes) { { '101' => { 'name' => 'hundred and one' } } }
+
+      it 'returns nil' do
+        expect(embedded).to be_nil
+      end
+    end
+
+    context 'when the attributes are deeply nested' do
+      let(:attributes) { { '100' => { 'name' => { 300 => %w[a b c] } } } }
+
+      it 'retrieves the embedded subset of attributes' do
+        expect(embedded).to eq(300 => %w[a b c])
+      end
+
+      context 'when the path is deeply nested' do
+        let(:path) { '100.name.300.1' }
+
+        it 'retrieves the embedded value' do
+          expect(embedded).to eq 'b'
+        end
+      end
+    end
+  end
+end

spec/mongoid/extensions/hash_spec.rb

@@ -220,68 +220,6 @@
     end
   end
 
-  context "when the hash key is a string" do
-
-    let(:hash) do
-      { "100" => { "name" => "hundred" } }
-    end
-
-    let(:nested) do
-      hash.__nested__("100.name")
-    end
-
-    it "should retrieve a nested value under the provided key" do
-      expect(nested).to eq "hundred"
-    end
-
-    context 'and the value is falsey' do
-      let(:hash) do
-        { "100" => { "name" => false } }
-      end
-      it "should retrieve the falsey nested value under the provided key" do
-        expect(nested).to eq false
-      end
-    end
-
-    context 'and the value is nil' do
-      let(:hash) do
-        { "100" => { 0 => "Please don't return this value!" } }
-      end
-      it "should retrieve the nil nested value under the provided key" do
-        expect(nested).to eq nil
-      end
-    end
-  end
-
-  context "when the hash key is an integer" do
-    let(:hash) do
-      { 100 => { "name" => "hundred" } }
-    end
-
-    let(:nested) do
-      hash.__nested__("100.name")
-    end
-
-    it "should retrieve a nested value under the provided key" do
-      expect(nested).to eq("hundred")
-    end
-  end
-
-  context "when the parent key is not present" do
-
-    let(:hash) do
-      { "101" => { "name" => "hundred and one" } }
-    end
-
-    let(:nested) do
-      hash.__nested__("100.name")
-    end
-
-    it "should return nil" do
-      expect(nested).to eq(nil)
-    end
-  end
-
   describe ".demongoize" do
 
     let(:hash) do