Fixes an issue with select_options on nil/blank objects

This was a regression from 2.x where the ActiveRecord object was setting
enum options on itself. Because these options were no longer available,
there was no way to determine the associated enum if the value was nil
or blank. This introduces a sort of null object that is just a subclass
of the base enum that behaves like a nil or blank object.

CHANGELOG.md

@@ -1,5 +1,12 @@
 # ClassyEnum Changelog
 
+## 3.1.1
+
+* Fixes a regression with Formtastic support. ClassyEnumm::Base.build now
+  returns a null object that decends from the base_class when the argument is
+  blank (nil, empty string, etc). This allows the ActiveRecord model's enum
+  attribute to respond to enum methods even if it is blank.
+
 ## 3.1.0
 
 * ClassyEnum::Base now extends Enumerable to provide enum collection

lib/classy_enum/base.rb

@@ -13,6 +13,8 @@ class Base
 
     class << self
       def inherited(klass)
+        return if klass.anonymous?
+
         if self == ClassyEnum::Base
           klass.base_class = klass
         else
@@ -59,7 +61,15 @@ def inherited(klass)
       def build(value, options={})
         object = find(value)
 
-        return value if object.nil? || (options[:allow_blank] && object.nil?)
+        if object.nil? || (options[:allow_blank] && object.nil?)
+          return value unless value.blank?
+
+          # Subclass the base class and make it behave like the value that it is
+          object = Class.new(base_class) {
+            instance_variable_set(:@option, value)
+            delegate :blank?, :nil?, :to => :option
+          }.new
+        end
 
         object.owner = options[:owner]
         object.serialize_as_json = options[:serialize_as_json]

lib/classy_enum/conversion.rb

@@ -28,14 +28,13 @@ def to_i
     #  class Priority < ClassyEnum::Base
     #  end
     #
-    #  class Priority::Low < Priority; end
-    #  class Priority::Medium < Priority; end
+    #  class Priority::Low < Priority; end #  class Priority::Medium < Priority; end
     #  class Priority::High < Priority; end
     #
     #  @priority = Priority::Low.new
     #  @priority.to_s # => 'low'
     def to_s
-      self.class.instance_variable_get('@option').to_s
+      option.to_s
     end
 
     # Returns a Symbol corresponding to a string representation of element,
@@ -65,5 +64,11 @@ def as_json(options=nil)
       json
     end
 
+    private
+
+    def option
+      self.class.instance_variable_get(:@option)
+    end
+
   end
 end

lib/classy_enum/version.rb

@@ -1,3 +1,3 @@
 module ClassyEnum
-  VERSION = "3.1.0"
+  VERSION = "3.1.1"
 end

spec/classy_enum/base_spec.rb

@@ -26,6 +26,20 @@ class ClassyEnumBase::Two < ClassyEnumBase
       subject { ClassyEnumBase.build(:two) }
       it { should be_a(ClassyEnumBase::Two) }
     end
+
+    context 'nil' do
+      subject { ClassyEnumBase.build(nil) }
+      it { should be_a(ClassyEnumBase) }
+      it { should be_nil }
+      it { should be_blank }
+    end
+
+    context 'empty string' do
+      subject { ClassyEnumBase.build('') }
+      it { should be_a(ClassyEnumBase) }
+      it { should_not be_nil }
+      it { should be_blank }
+    end
   end
 
   context '#new' do