Remove ActiveModel dependency from ActionPack

ActiveModel is used in ActionPack for ActiveModel::Naming for a few,
mostly optional aspects of ActionPack related to automatically converting
an ActiveModel compliant object into a key for params and routing. It uses
only three methods of ActiveModel (ActiveModel::Naming.route_key,
ActiveModel::Naming.singular_route_key and ActiveModel::Naming.param_key).

actionpack/actionpack.gemspec

@@ -18,13 +18,13 @@ Gem::Specification.new do |s|
   s.requirements << 'none'
 
   s.add_dependency('activesupport', version)
-  s.add_dependency('activemodel',   version)
   s.add_dependency('rack-cache',    '~> 1.2')
   s.add_dependency('builder',       '~> 3.0.0')
   s.add_dependency('rack',          '~> 1.4.1')
   s.add_dependency('rack-test',     '~> 0.6.1')
   s.add_dependency('journey',       '~> 1.0.1')
   s.add_dependency('erubis',        '~> 2.7.0')
 
+  s.add_development_dependency('activemodel', version)
   s.add_development_dependency('tzinfo', '~> 0.3.33')
 end

actionpack/lib/action_controller/model_naming.rb

@@ -0,0 +1,12 @@
+module ActionController
+  module ModelNaming
+    # Converts the given object to an ActiveModel compliant one.
+    def convert_to_model(object)
+      object.respond_to?(:to_model) ? object.to_model : object
+    end
+
+    def model_name_from_record_or_class(record_or_class)
+      (record_or_class.is_a?(Class) ? record_or_class : convert_to_model(record_or_class).class).model_name
+    end
+  end
+end

actionpack/lib/action_controller/record_identifier.rb

@@ -1,4 +1,5 @@
 require 'active_support/core_ext/module'
+require 'action_controller/model_naming'
 
 module ActionController
   # The record identifier encapsulates a number of naming conventions for dealing with records, like Active Records or
@@ -27,6 +28,8 @@ module ActionController
   module RecordIdentifier
     extend self
 
+    include ModelNaming
+
     JOIN = '_'.freeze
     NEW = 'new'.freeze
 
@@ -40,7 +43,7 @@ module RecordIdentifier
     #   dom_class(post, :edit)   # => "edit_post"
     #   dom_class(Person, :edit) # => "edit_person"
     def dom_class(record_or_class, prefix = nil)
-      singular = ActiveModel::Naming.param_key(record_or_class)
+      singular = model_name_from_record_or_class(record_or_class).param_key
       prefix ? "#{prefix}#{JOIN}#{singular}" : singular
     end
 
@@ -73,8 +76,7 @@ def dom_id(record, prefix = nil)
     # method that replaces all characters that are invalid inside DOM ids, with valid ones. You need to
     # make sure yourself that your dom ids are valid, in case you overwrite this method.
     def record_key_for_dom_id(record)
-      record = record.to_model if record.respond_to?(:to_model)
-      key = record.to_key
+      key = convert_to_model(record).to_key
       key ? key.join('_') : key
     end
   end

actionpack/lib/action_dispatch/routing/polymorphic_routes.rb

@@ -1,3 +1,5 @@
+require 'action_controller/model_naming'
+
 module ActionDispatch
   module Routing
     # Polymorphic URL helpers are methods for smart resolution to a named route call when
@@ -53,6 +55,8 @@ module Routing
     #   form_for([blog, @post])         # => "/blog/posts/1"
     #
     module PolymorphicRoutes
+      include ActionController::ModelNaming
+
       # Constructs a call to a named RESTful route for the given record and returns the
       # resulting URL string. For example:
       #
@@ -154,10 +158,6 @@ def action_prefix(options)
           options[:action] ? "#{options[:action]}_" : ''
         end
 
-        def convert_to_model(object)
-          object.respond_to?(:to_model) ? object.to_model : object
-        end
-
         def routing_type(options)
           options[:routing_type] || :url
         end
@@ -169,7 +169,7 @@ def build_named_route_call(records, inflection, options = {})
               if parent.is_a?(Symbol) || parent.is_a?(String)
                 parent
               else
-                ActiveModel::Naming.singular_route_key(parent)
+                model_name_from_record_or_class(parent).singular_route_key
               end
             end
           else
@@ -181,9 +181,9 @@ def build_named_route_call(records, inflection, options = {})
             route << record
           elsif record
             if inflection == :singular
-              route << ActiveModel::Naming.singular_route_key(record)
+              route << model_name_from_record_or_class(record).singular_route_key
             else
-              route << ActiveModel::Naming.route_key(record)
+              route << model_name_from_record_or_class(record).route_key
             end
           else
             raise ArgumentError, "Nil location provided. Can't build URI."

actionpack/lib/action_view/helpers/form_helper.rb

@@ -12,6 +12,7 @@
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/deprecation'
 require 'active_support/core_ext/string/inflections'
+require 'action_controller/model_naming'
 
 module ActionView
   # = Action View Form Helpers
@@ -117,11 +118,7 @@ module FormHelper
 
       include FormTagHelper
       include UrlHelper
-
-      # Converts the given object to an ActiveModel compliant one.
-      def convert_to_model(object)
-        object.respond_to?(:to_model) ? object.to_model : object
-      end
+      include ActionController::ModelNaming
 
       # Creates a form that allows the user to create or update the attributes
       # of a specific model object.
@@ -411,7 +408,7 @@ def form_for(record, options = {}, &proc)
           object      = nil
         else
           object      = record.is_a?(Array) ? record.last : record
-          object_name = options[:as] || ActiveModel::Naming.param_key(object)
+          object_name = options[:as] || model_name_from_record_or_class(object).param_key
           apply_form_for_options!(record, object, options)
         end
 
@@ -1128,7 +1125,7 @@ def instantiate_builder(record_name, record_object, options)
             object_name = record_name
           else
             object = record_name
-            object_name = ActiveModel::Naming.param_key(object)
+            object_name = model_name_from_record_or_class(object).param_key
           end
 
           builder = options[:builder] || default_form_builder
@@ -1142,9 +1139,11 @@ def default_form_builder
     end
 
     class FormBuilder
+      include ActionController::ModelNaming
+
       # The methods which wrap a form helper call.
       class_attribute :field_helpers
-      self.field_helpers = FormHelper.instance_methods - [:form_for, :convert_to_model]
+      self.field_helpers = FormHelper.instance_methods - [:form_for, :convert_to_model, :model_name_from_record_or_class]
 
       attr_accessor :object_name, :object, :options
 
@@ -1214,7 +1213,7 @@ def fields_for(record_name, record_object = nil, fields_options = {}, &block)
           end
         else
           record_object = record_name.is_a?(Array) ? record_name.last : record_name
-          record_name   = ActiveModel::Naming.param_key(record_object)
+          record_name   = model_name_from_record_or_class(record_object).param_key
         end
 
         index = if options.has_key?(:index)
@@ -1396,10 +1395,6 @@ def nested_child_index(name)
           @nested_child_index[name] ||= -1
           @nested_child_index[name] += 1
         end
-
-        def convert_to_model(object)
-          object.respond_to?(:to_model) ? object.to_model : object
-        end
     end
   end