Improve docs and code.

lib/inherited_resources/class_methods.rb

@@ -279,6 +279,7 @@ def acts_as_polymorphic! #:nodoc:
       end
 
       def acts_as_shallow! #:nodoc:
+        include BelongsToHelpers
         include ShallowHelpers
       end
 

lib/inherited_resources/shallow_helpers.rb

@@ -1,40 +1,43 @@
 module InheritedResources
+  # Shallow provides a functionality that goes on pair with Rails' shallow.
+  # It is very similar to "optional" but it actually finds all the parents
+  # resources instead of leaving them blank. Consider the following example:
+  #
+  #   belongs_to :post, :shallow => true do
+  #     belongs_to :comment
+  #   end
+  #
+  # When accessed as /comments/1, Inherited Resources will automatically get
+  # the post resource so both objects are actually accessible through the views.
+  #
+  # However, when using optional, Inherited Resources wouldn't actually bother
+  # with finding the parent object.
   module ShallowHelpers
-    include BelongsToHelpers
-
     private
 
-      # Evaluate the parent given. This is used to nest parents in the
-      # association chain.
-      #
-
-      # Maps parents_symbols to build association chain. In this case, it
-      # simply return the parent_symbols, however on polymorphic belongs to,
-      # it has some customization.
-      #
       def symbols_for_association_chain #:nodoc:
         parent_symbols = parents_symbols.dup
-        if parents_symbols.size > 1 && !params[:id]
-          inst_class_name = parent_symbols.pop
-          finder_method = resources_configuration[inst_class_name][:finder] || :find
-          instance = resources_configuration[inst_class_name][:parent_class].send(finder_method, params[resources_configuration[inst_class_name][:param]])
-          load_parents(instance, parent_symbols)
-        end
-        if params[:id]
+        instance = nil
+
+        if id = params[:id]
           finder_method = resources_configuration[:self][:finder] || :find
-          instance = self.resource_class.send(finder_method, params[:id])
-          load_parents(instance, parent_symbols)
+          instance      = self.resource_class.send(finder_method, id)
+        elsif parents_symbols.size > 1
+          config         = resources_configuration[parent_symbols.pop]
+          finder_method  = config[:finder] || :find
+          instance       = config[:parent_class].send(finder_method, params[config[:param]])
         end
+
+        load_parents(instance, parent_symbols) if instance
         parents_symbols
       end
 
       def load_parents(instance, parent_symbols)
-
         parent_symbols.reverse.each do |parent|
           instance = instance.send(parent)
-          params[resources_configuration[parent][:param]] = instance.to_param
+          config   = resources_configuration[parent]
+          params[config[:param]] = instance.to_param
         end
       end
   end
-
 end