Remove ActiveRecord::Model

In the end I think the pain of implementing this seamlessly was not
worth the gain provided.

The intention was that it would allow plain ruby objects that might not
live in your main application to be subclassed and have persistence
mixed in. But I've decided that the benefit of doing that is not worth
the amount of complexity that the implementation introduced.

Author: jonleighton

activerecord/CHANGELOG.md

@@ -926,34 +926,6 @@
 
     *Aaron Patterson*
 
-*   Added the `ActiveRecord::Model` module which can be included in a
-    class as an alternative to inheriting from `ActiveRecord::Base`:
-
-        class Post
-          include ActiveRecord::Model
-        end
-
-    Please note:
-
-      * Up until now it has been safe to assume that all AR models are
-        descendants of `ActiveRecord::Base`. This is no longer a safe
-        assumption, but it may transpire that there are areas of the
-        code which still make this assumption. So there may be
-        'teething difficulties' with this feature. (But please do try it
-        and report bugs.)
-
-      * Plugins & libraries etc that add methods to `ActiveRecord::Base`
-        will not be compatible with `ActiveRecord::Model`. Those libraries
-        should add to `ActiveRecord::Model` instead (which is included in
-        `Base`), or better still, avoid monkey-patching AR and instead
-        provide a module that users can include where they need it.
-
-      * To minimise the risk of conflicts with other code, it is
-        advisable to include `ActiveRecord::Model` early in your class
-        definition.
-
-    *Jon Leighton*
-
 *   PostgreSQL hstore records can be created.
 
     *Aaron Patterson*

activerecord/lib/active_record.rb

@@ -43,7 +43,6 @@ module ActiveRecord
   autoload :Integration
   autoload :Migration
   autoload :Migrator, 'active_record/migration'
-  autoload :Model
   autoload :ModelSchema
   autoload :NestedAttributes
   autoload :Observer

activerecord/lib/active_record/associations/alias_tracker.rb

@@ -8,7 +8,7 @@ class AliasTracker # :nodoc:
       attr_reader :aliases, :table_joins, :connection
 
       # table_joins is an array of arel joins which might conflict with the aliases we assign here
-      def initialize(connection = ActiveRecord::Model.connection, table_joins = [])
+      def initialize(connection = Base.connection, table_joins = [])
         @aliases     = Hash.new { |h,k| h[k] = initial_count_for(k) }
         @table_joins = table_joins
         @connection  = connection

activerecord/lib/active_record/attribute_methods.rb

@@ -59,7 +59,7 @@ def instance_method_already_implemented?(method_name)
           raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord"
         end
 
-        if [Base, Model].include?(active_record_super)
+        if superclass == Base
           super
         else
           # If B < A and A defines its own attribute method, then we don't want to overwrite that.

activerecord/lib/active_record/attribute_methods/dirty.rb

@@ -2,11 +2,6 @@
 require 'active_support/deprecation'
 
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :partial_writes, instance_accessor: false
-    self.partial_writes = true
-  end
-
   module AttributeMethods
     module Dirty # :nodoc:
       extend ActiveSupport::Concern
@@ -18,7 +13,8 @@ module Dirty # :nodoc:
           raise "You cannot include Dirty after Timestamp"
         end
 
-        config_attribute :partial_writes
+        class_attribute :partial_writes, instance_writer: false
+        self.partial_writes = true
 
         def self.partial_updates=(v); self.partial_writes = v; end
         def self.partial_updates?; partial_writes?; end

activerecord/lib/active_record/attribute_methods/read.rb

@@ -1,16 +1,13 @@
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :attribute_types_cached_by_default, instance_accessor: false
-  end
-
   module AttributeMethods
     module Read
       extend ActiveSupport::Concern
 
       ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date]
 
       included do
-        config_attribute :attribute_types_cached_by_default
+        class_attribute :attribute_types_cached_by_default, instance_writer: false
+        self.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
       end
 
       module ClassMethods
@@ -79,8 +76,6 @@ def cacheable_column?(column)
         end
       end
 
-      ActiveRecord::Model.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
-
       # Returns the value of the attribute identified by <tt>attr_name</tt> after
       # it has been typecast (for example, "2004-12-12" in a data column is cast
       # to a date object, like Date.new(2004, 12, 12)).

activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb

@@ -1,13 +1,4 @@
-
 module ActiveRecord
-  ActiveSupport.on_load(:active_record_config) do
-    mattr_accessor :time_zone_aware_attributes, instance_accessor: false
-    self.time_zone_aware_attributes = false
-
-    mattr_accessor :skip_time_zone_conversion_for_attributes, instance_accessor: false
-    self.skip_time_zone_conversion_for_attributes = []
-  end
-
   module AttributeMethods
     module TimeZoneConversion
       class Type # :nodoc:
@@ -28,8 +19,11 @@ def type
       extend ActiveSupport::Concern
 
       included do
-        config_attribute :time_zone_aware_attributes, global: true
-        config_attribute :skip_time_zone_conversion_for_attributes
+        mattr_accessor :time_zone_aware_attributes, instance_writer: false
+        self.time_zone_aware_attributes = false
+
+        class_attribute :skip_time_zone_conversion_for_attributes, instance_writer: false
+        self.skip_time_zone_conversion_for_attributes = []
       end
 
       module ClassMethods

activerecord/lib/active_record/base.rb

@@ -321,8 +321,48 @@ module ActiveRecord #:nodoc:
   # So it's possible to assign a logger to the class through <tt>Base.logger=</tt> which will then be used by all
   # instances in the current object space.
   class Base
-    include ActiveRecord::Model
+    extend ActiveModel::Observing::ClassMethods
+    extend ActiveModel::Naming
+
+    extend ActiveSupport::Benchmarkable
+    extend ActiveSupport::DescendantsTracker
+
+    extend ConnectionHandling
+    extend QueryCache::ClassMethods
+    extend Querying
+    extend Translation
+    extend DynamicMatchers
+    extend Explain
+    extend ConnectionHandling
+
+    include Persistence
+    include ReadonlyAttributes
+    include ModelSchema
+    include Inheritance
+    include Scoping
+    include Sanitization
+    include AttributeAssignment
+    include ActiveModel::Conversion
+    include Integration
+    include Validations
+    include CounterCache
+    include Locking::Optimistic
+    include Locking::Pessimistic
+    include AttributeMethods
+    include Callbacks
+    include ActiveModel::Observing
+    include Timestamp
+    include Associations
+    include ActiveModel::SecurePassword
+    include AutosaveAssociation
+    include NestedAttributes
+    include Aggregations
+    include Transactions
+    include Reflection
+    include Serialization
+    include Store
+    include Core
   end
-end
 
-ActiveSupport.run_load_hooks(:active_record, ActiveRecord::Model::DeprecationProxy.new)
+  ActiveSupport.run_load_hooks(:active_record, Base)
+end

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -441,11 +441,11 @@ def release(conn)
       end
 
       def new_connection
-        ActiveRecord::Model.send(spec.adapter_method, spec.config)
+        Base.send(spec.adapter_method, spec.config)
       end
 
       def current_connection_id #:nodoc:
-        ActiveRecord::Model.connection_id ||= Thread.current.object_id
+        Base.connection_id ||= Thread.current.object_id
       end
 
       def checkout_new_connection
@@ -567,10 +567,10 @@ def retrieve_connection_pool(klass)
         class_to_pool[klass] ||= begin
           until pool = pool_for(klass)
             klass = klass.superclass
-            break unless klass < ActiveRecord::Tag
+            break unless klass <= Base
           end
 
-          class_to_pool[klass] = pool || pool_for(ActiveRecord::Model)
+          class_to_pool[klass] = pool
         end
       end
 

activerecord/lib/active_record/connection_handling.rb

@@ -1,4 +1,3 @@
-
 module ActiveRecord
   module ConnectionHandling
     # Establishes the connection to the database. Accepts a hash as input where