Merge 20823ff into 2e31a14

README.md

@@ -1,5 +1,5 @@
-[![Build Status](https://api.travis-ci.org/rails-api/active_model_serializers.png)](https://travis-ci.org/rails-api/active_model_serializers) 
-[![Code Climate](https://codeclimate.com/github/rails-api/active_model_serializers.png)](https://codeclimate.com/github/rails-api/active_model_serializers) 
+[![Build Status](https://api.travis-ci.org/rails-api/active_model_serializers.png)](https://travis-ci.org/rails-api/active_model_serializers)
+[![Code Climate](https://codeclimate.com/github/rails-api/active_model_serializers.png)](https://codeclimate.com/github/rails-api/active_model_serializers)
 [![Coverage Status](https://coveralls.io/repos/rails-api/active_model_serializers/badge.png?branch=master)](https://coveralls.io/r/rails-api/active_model_serializers)
 
 # ActiveModel::Serializers
@@ -14,8 +14,8 @@ If you want to read the stable documentation visit [0.8 README](https://github.c
 
 ## Purpose
 
-`ActiveModel::Serializers` encapsulates the JSON serialization of objects. 
-Objects that respond to read\_attribute\_for\_serialization 
+`ActiveModel::Serializers` encapsulates the JSON serialization of objects.
+Objects that respond to read\_attribute\_for\_serialization
 (including `ActiveModel` and `ActiveRecord` objects) are supported.
 
 Serializers know about both a model and the `current_user`, so you can
@@ -71,7 +71,7 @@ $ rails g serializer post
 
 Currently `ActiveModel::Serializers` expects objects to implement
 read\_attribute\_for\_serialization. That's all you need to do to have
-your POROs supported. 
+your POROs supported.
 
 # render :json
 
@@ -302,6 +302,19 @@ class PostSerializer < ActiveModel::Serializer
 end
 ```
 
+Also you can use `if` parameter to `attributes` like this:
+
+```ruby
+class PostSerializer < ActiveModel::Serializer
+  attributes :id, :title
+  attributes :body, :author, :if => :shows_body_and_author?
+
+  def shows_body_and_author?
+    [true, false].sample # Confuse client side developers with randomly absent attributes
+  end
+end
+```
+
 And it's also safe to mutate keys argument by doing keys.delete(:author)
 in case you want to avoid creating two extra arrays. Note that if you do an
 in-place modification, you still need to return the modified array.
@@ -573,8 +586,8 @@ this:
 }
 ```
 
-When side-loading data, your serializer cannot have the `{ root: false }` option, 
-as this would lead to invalid JSON. If you do not have a root key, the `include` 
+When side-loading data, your serializer cannot have the `{ root: false }` option,
+as this would lead to invalid JSON. If you do not have a root key, the `include`
 instruction will be ignored
 
 You can also specify a different root for the embedded objects than the key

lib/active_model/serializer.rb

@@ -16,6 +16,7 @@ def inherited(base)
         base._root = _root
         base._attributes = (_attributes || []).dup
         base._associations = (_associations || {}).dup
+        base._conditions = (@_conditions || {}).dup
       end
 
       def setup
@@ -60,17 +61,28 @@ def serializer_for(resource)
         end
       end
 
-      attr_accessor :_root, :_attributes, :_associations
+      attr_accessor :_root, :_attributes, :_associations, :_conditions
       alias root  _root=
       alias root= _root=
 
       def root_name
         name.demodulize.underscore.sub(/_serializer$/, '') if name
       end
 
-      def attributes(*attrs)
+      def attributes(*args)
+        attrs, options = if args.last.kind_of? Hash
+                           [args[0, args.size - 1], args.last]
+                         else
+                           [args, {}]
+                         end
+
         @_attributes.concat attrs
 
+        if condition = options[:if]
+          attrs_list = @_conditions[condition]
+          @_conditions[condition] = (attrs_list || []).concat(attrs).compact
+        end
+
         attrs.each do |attr|
           define_method attr do
             object.read_attribute_for_serialization attr
@@ -110,8 +122,16 @@ def initialize(object, options={})
       @wrap_in_array = options[:_wrap_in_array]
       @only          = Array(options[:only]) if options[:only]
       @except        = Array(options[:except]) if options[:except]
+      @conditions_cache = {}
+
+      self.class._conditions.map do |condition, attrs|
+        condition = {resolved: false, method: condition}
+        attrs.each do |attr|
+          conditions_cache[attr] = condition
+        end
+      end
     end
-    attr_accessor :object, :scope, :root, :meta_key, :meta
+    attr_accessor :object, :scope, :root, :meta_key, :meta, :conditions_cache
 
     def json_key
       if root == true || root.nil?
@@ -142,9 +162,11 @@ def associations
     end
 
     def filter(keys)
+      @except = (@except || []).concat check_conditions
+
       if @only
         keys & @only
-      elsif @except
+      elsif @except.any?
         keys - @except
       else
         keys
@@ -197,5 +219,16 @@ def serializable_object(options={})
       @wrap_in_array ? [hash] : hash
     end
     alias_method :serializable_hash, :serializable_object
+
+    def check_conditions
+      conditions_cache.map do |attr, condition|
+        unless condition[:resolved]
+          condition[:resolved] = true
+          condition[:result] = send(condition[:method])
+        end
+
+        attr unless condition[:result]
+      end.compact
+    end
   end
 end

test/fixtures/poro.rb

@@ -50,7 +50,21 @@ def description
     scope ? "#{description} - #{scope}" : description
   end
 
-  attributes :name, :description
+  def show_me
+    raise "No way!"
+  end
+
+  def should_show_me
+    false
+  end
+
+  def should_show_description
+    true
+  end
+
+  attributes :name
+  attributes :description, :if => :should_show_description
+  attributes :show_me, :if => :should_show_me
 end
 
 class PostSerializer < ActiveModel::Serializer

test/unit/active_model/serializer/attributes_test.rb

@@ -9,7 +9,7 @@ def setup
       end
 
       def test_attributes_definition
-        assert_equal([:name, :description],
+        assert_equal([:name, :description, :show_me],
                      @profile_serializer.class._attributes)
       end
 
@@ -31,9 +31,9 @@ def test_attributes_inheritance
         end
         another_inherited_serializer_klass = Class.new(ProfileSerializer)
 
-        assert_equal([:name, :description, :comments],
+        assert_equal([:name, :description, :show_me, :comments],
                      inherited_serializer_klass._attributes)
-        assert_equal([:name, :description],
+        assert_equal([:name, :description, :show_me],
                      another_inherited_serializer_klass._attributes)
       end
     end

test/unit/active_model/serializer/filter_test.rb

@@ -28,7 +28,7 @@ def setup
         @profile_serializer = ProfileSerializer.new(@profile)
         @profile_serializer.instance_eval do
           def filter(keys)
-            keys - [:description]
+            keys - [:description, :show_me]
           end
         end
       end