Implements the store_accessor method (Closes #280)

.ruby_version

@@ -0,0 +1 @@
+2.7

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- ActiveRecord `store_accessor` helper method
 
 ## [0.40.0] - 2021-10-16
 ### Fixed

lib/no_brainer/document.rb

@@ -7,7 +7,7 @@ module NoBrainer::Document
   autoload_and_include :Core, :TableConfig, :InjectionLayer, :Attributes, :Readonly,
                        :Persistance, :Callbacks, :Validation, :Types, :Dirty, :PrimaryKey,
                        :Association, :Serialization, :Criteria, :Polymorphic, :Index, :Aliases,
-                       :MissingAttributes, :LazyFetch, :AtomicOps, :VirtualAttributes
+                       :MissingAttributes, :LazyFetch, :AtomicOps, :VirtualAttributes, :Store
 
   autoload :DynamicAttributes, :Timestamps
 

lib/no_brainer/document/store.rb

@@ -0,0 +1,286 @@
+# frozen_string_literal: true
+
+require 'active_support/core_ext/hash/indifferent_access'
+
+module NoBrainer
+  module Document
+    # Store gives you a thin wrapper around serialize for the purpose of storing hashes in a single column.
+    # It's like a simple key/value store baked into your record when you don't care about being able to
+    # query that store outside the context of a single record.
+    #
+    # You can then declare accessors to this store that are then accessible just like any other attribute
+    # of the model. This is very helpful for easily exposing store keys to a form or elsewhere that's
+    # already built around just accessing attributes on the model.
+    #
+    # Every accessor comes with dirty tracking methods (+key_changed?+, +key_was+ and +key_change+) and
+    # methods to access the changes made during the last save (+saved_change_to_key?+, +saved_change_to_key+ and
+    # +key_before_last_save+).
+    #
+    # NOTE: There is no +key_will_change!+ method for accessors, use +store_will_change!+ instead.
+    #
+    # Make sure that you declare the database column used for the serialized store as a text, so there's
+    # plenty of room.
+    #
+    # You can set custom coder to encode/decode your serialized attributes to/from different formats.
+    # JSON, YAML, Marshal are supported out of the box. Generally it can be any wrapper that provides +load+ and +dump+.
+    #
+    # NOTE: If you are using structured database data types (e.g. PostgreSQL +hstore+/+json+, or MySQL 5.7+
+    # +json+) there is no need for the serialization provided by {.store}[rdoc-ref:rdoc-ref:ClassMethods#store].
+    # Simply use {.store_accessor}[rdoc-ref:ClassMethods#store_accessor] instead to generate
+    # the accessor methods. Be aware that these columns use a string keyed hash and do not allow access
+    # using a symbol.
+    #
+    # NOTE: The default validations with the exception of +uniqueness+ will work.
+    # For example, if you want to check for +uniqueness+ with +hstore+ you will
+    # need to use a custom validation to handle it.
+    #
+    # Examples:
+    #
+    #   class User < ActiveRecord::Base
+    #     store :settings, accessors: [ :color, :homepage ], coder: JSON
+    #     store :parent, accessors: [ :name ], coder: JSON, prefix: true
+    #     store :spouse, accessors: [ :name ], coder: JSON, prefix: :partner
+    #     store :settings, accessors: [ :two_factor_auth ], suffix: true
+    #     store :settings, accessors: [ :login_retry ], suffix: :config
+    #   end
+    #
+    #   u = User.new(color: 'black', homepage: '37signals.com', parent_name: 'Mary', partner_name: 'Lily')
+    #   u.color                          # Accessor stored attribute
+    #   u.parent_name                    # Accessor stored attribute with prefix
+    #   u.partner_name                   # Accessor stored attribute with custom prefix
+    #   u.two_factor_auth_settings       # Accessor stored attribute with suffix
+    #   u.login_retry_config             # Accessor stored attribute with custom suffix
+    #   u.settings[:country] = 'Denmark' # Any attribute, even if not specified with an accessor
+    #
+    #   # There is no difference between strings and symbols for accessing custom attributes
+    #   u.settings[:country]  # => 'Denmark'
+    #   u.settings['country'] # => 'Denmark'
+    #
+    #   # Dirty tracking
+    #   u.color = 'green'
+    #   u.color_changed? # => true
+    #   u.color_was # => 'black'
+    #   u.color_change # => ['black', 'red']
+    #
+    #   # Add additional accessors to an existing store through store_accessor
+    #   class SuperUser < User
+    #     store_accessor :settings, :privileges, :servants
+    #     store_accessor :parent, :birthday, prefix: true
+    #     store_accessor :settings, :secret_question, suffix: :config
+    #   end
+    #
+    # The stored attribute names can be retrieved using {.stored_attributes}[rdoc-ref:rdoc-ref:ClassMethods#stored_attributes].
+    #
+    #   User.stored_attributes[:settings] # [:color, :homepage, :two_factor_auth, :login_retry]
+    #
+    # == Overwriting default accessors
+    #
+    # All stored values are automatically available through accessors on the Active Record
+    # object, but sometimes you want to specialize this behavior. This can be done by overwriting
+    # the default accessors (using the same name as the attribute) and calling <tt>super</tt>
+    # to actually change things.
+    #
+    #   class Song < ActiveRecord::Base
+    #     # Uses a stored integer to hold the volume adjustment of the song
+    #     store :settings, accessors: [:volume_adjustment]
+    #
+    #     def volume_adjustment=(decibels)
+    #       super(decibels.to_i)
+    #     end
+    #
+    #     def volume_adjustment
+    #       super.to_i
+    #     end
+    #   end
+    module Store
+      extend ActiveSupport::Concern
+
+      included do
+        class << self
+          attr_accessor :local_stored_attributes
+        end
+      end
+
+      module ClassMethods
+        def store(store_attribute, options = {})
+          store_accessor(store_attribute, options[:accessors], **options.slice(:prefix, :suffix)) if options.has_key? :accessors
+        end
+
+        def store_accessor(store_attribute, *keys, prefix: nil, suffix: nil)
+          keys = keys.flatten
+
+          accessor_prefix =
+            case prefix
+            when String, Symbol
+              "#{prefix}_"
+            when TrueClass
+              "#{store_attribute}_"
+            else
+              ""
+            end
+          accessor_suffix =
+            case suffix
+            when String, Symbol
+              "_#{suffix}"
+            when TrueClass
+              "_#{store_attribute}"
+            else
+              ""
+            end
+
+          field store_attribute, type: Hash, default: {} unless has_field?(store_attribute)
+
+          define_method("#{store_attribute}=") do |value|
+            super(value) if value.is_a?(Hash) || value.nil?
+          end
+
+          _store_accessors_module.module_eval do
+            keys.each do |key|
+              accessor_key = "#{accessor_prefix}#{key}#{accessor_suffix}"
+
+              define_method("#{accessor_key}=") do |value|
+                write_store_attribute(store_attribute, key, value)
+              end
+
+              define_method(accessor_key) do
+                read_store_attribute(store_attribute, key)
+              end
+
+              define_method("#{accessor_key}_changed?") do
+                return false unless __send__("#{store_attribute}_changed?")
+                prev_store, new_store = changes[store_attribute]
+                prev_store&.dig(key) != new_store&.dig(key)
+              end
+
+              define_method("#{accessor_key}_change") do
+                return unless __send__("#{store_attribute}_changed?")
+                prev_store, new_store = changes[store_attribute]
+                [prev_store&.dig(key), new_store&.dig(key)]
+              end
+
+              define_method("#{accessor_key}_was") do
+                return unless __send__("#{store_attribute}_changed?")
+                prev_store, _new_store = changes[store_attribute]
+                prev_store&.dig(key)
+              end
+
+              # NoBrainer doesn't have `attribute_will_change!` so those methods
+              # can't be implemented yet.
+              # See https://github.com/NoBrainerORM/nobrainer/pull/190
+              #
+              # define_method("saved_change_to_#{accessor_key}?") do
+              #   return false unless __send__("saved_change_to_#{store_attribute}?")
+              #   prev_store, new_store = __send__("saved_change_to_#{store_attribute}")
+              #   prev_store&.dig(key) != new_store&.dig(key)
+              # end
+
+              # define_method("saved_change_to_#{accessor_key}") do
+              #   return unless __send__("saved_change_to_#{store_attribute}?")
+              #   prev_store, new_store = __send__("saved_change_to_#{store_attribute}")
+              #   [prev_store&.dig(key), new_store&.dig(key)]
+              # end
+
+              # define_method("#{accessor_key}_before_last_save") do
+              #   return unless __send__("saved_change_to_#{store_attribute}?")
+              #   prev_store, _new_store = __send__("saved_change_to_#{store_attribute}")
+              #   prev_store&.dig(key)
+              # end
+            end
+          end
+
+          # assign new store attribute and create new hash to ensure that each class in the hierarchy
+          # has its own hash of stored attributes.
+          self.local_stored_attributes ||= {}
+          self.local_stored_attributes[store_attribute] ||= []
+          self.local_stored_attributes[store_attribute] |= keys
+        end
+
+        def _store_accessors_module # :nodoc:
+          @_store_accessors_module ||= begin
+            mod = Module.new
+            include mod
+            mod
+          end
+        end
+
+        def stored_attributes
+          parent = superclass.respond_to?(:stored_attributes) ? superclass.stored_attributes : {}
+          if local_stored_attributes
+            parent.merge!(local_stored_attributes) { |k, a, b| a | b }
+          end
+          parent
+        end
+      end
+
+      private
+
+      def read_store_attribute(store_attribute, key) # :doc:
+        StringKeyedHashAccessor.read(self, store_attribute, key)
+      end
+
+      def write_store_attribute(store_attribute, key, value) # :doc:
+        StringKeyedHashAccessor.write(self, store_attribute, key, value)
+      end
+
+      class HashAccessor # :nodoc:
+        def self.read(object, attribute, key)
+          prepare(object, attribute)
+          object.public_send(attribute)[key]
+        end
+
+        def self.write(object, attribute, key, value)
+          prepare(object, attribute)
+          if value != read(object, attribute, key)
+            # "#{attribute}_will_change!" is not implemented in NoBrainer. See issue #190
+            # object.public_send :"#{attribute}_will_change!"
+            object.public_send(attribute)[key] = value
+          end
+        end
+
+        def self.prepare(object, attribute)
+          object.public_send :"#{attribute}=", {} unless object.send(attribute)
+        end
+      end
+
+      class StringKeyedHashAccessor < HashAccessor # :nodoc:
+        def self.read(object, attribute, key)
+          super object, attribute, key.to_s
+        end
+
+        def self.write(object, attribute, key, value)
+          super object, attribute, key.to_s, value
+        end
+      end
+
+      class IndifferentCoder # :nodoc:
+        def initialize(attr_name, coder_or_class_name)
+          @coder =
+            if coder_or_class_name.respond_to?(:load) && coder_or_class_name.respond_to?(:dump)
+              coder_or_class_name
+            else
+              NoBrainer::Document::Coders::YAMLColumn.new(attr_name, coder_or_class_name || Object)
+            end
+        end
+
+        def dump(obj)
+          @coder.dump self.class.as_indifferent_hash(obj)
+        end
+
+        def load(yaml)
+          self.class.as_indifferent_hash(@coder.load(yaml || ""))
+        end
+
+        def self.as_indifferent_hash(obj)
+          case obj
+          when ActiveSupport::HashWithIndifferentAccess
+            obj
+          when Hash
+            obj.with_indifferent_access
+          else
+            ActiveSupport::HashWithIndifferentAccess.new
+          end
+        end
+      end
+    end
+  end
+end