Added serializer file digest to the cache_key

Fixes #901

lib/active_model/serializer.rb

@@ -19,6 +19,7 @@ module ActiveModel
       attr_accessor :_cache_only
       attr_accessor :_cache_except
       attr_accessor :_cache_options
+      attr_accessor :_cache_digest
     end
 
     def self.inherited(base)
@@ -26,6 +27,8 @@ module ActiveModel
       base._attributes_keys = {}
       base._associations = {}
       base._urls = []
+      serializer_file = File.open(caller.first[/^[^:]+/])
+      base._cache_digest = Digest::MD5.hexdigest(serializer_file.read)
     end
 
     def self.attributes(*attrs)

lib/active_model/serializer/adapter.rb

@@ -63,6 +63,13 @@ module ActiveModel
       end
 
       def cache_key
+        parts = []
+        parts << object_cache_key
+        parts << @klass._cache_digest unless @klass._cache_options && @klass._cache_options[:skip_digest]
+        parts.join("/")
+      end
+
+      def object_cache_key
         (@klass._cache_key) ? "#{@klass._cache_key}/#{@cached_serializer.object.id}-#{@cached_serializer.object.updated_at}" : @cached_serializer.object.cache_key
       end
 

test/fixtures/poro.rb

@@ -1,4 +1,6 @@
 class Model
+  FILE_DIGEST = Digest::MD5.hexdigest(File.open(__FILE__).read)
+
   def initialize(hash={})
     @attributes = hash
   end
@@ -7,6 +9,10 @@ class Model
     "#{self.class.name.downcase}/#{self.id}-#{self.updated_at}"
   end
 
+  def cache_key_with_digest
+    "#{cache_key}/#{FILE_DIGEST}"
+  end
+
   def updated_at
     @attributes[:updated_at] ||= DateTime.now.to_time.to_i
   end
@@ -64,7 +70,7 @@ Author   = Class.new(Model)
 Bio      = Class.new(Model)
 Blog     = Class.new(Model)
 Role     = Class.new(Model)
-User = Class.new(Model)
+User     = Class.new(Model)
 Location = Class.new(Model)
 Place    = Class.new(Model)
 
@@ -72,7 +78,7 @@ module Spam; end
 Spam::UnrelatedLink = Class.new(Model)
 
 PostSerializer = Class.new(ActiveModel::Serializer) do
-  cache key:'post', expires_in: 0.1
+  cache key:'post', expires_in: 0.1, skip_digest: true
   attributes :id, :title, :body
 
   has_many :comments
@@ -99,7 +105,7 @@ SpammyPostSerializer = Class.new(ActiveModel::Serializer) do
 end
 
 CommentSerializer = Class.new(ActiveModel::Serializer) do
-  cache expires_in: 1.day
+  cache expires_in: 1.day, skip_digest: true
   attributes :id, :body
 
   belongs_to :post
@@ -111,7 +117,7 @@ CommentSerializer = Class.new(ActiveModel::Serializer) do
 end
 
 AuthorSerializer = Class.new(ActiveModel::Serializer) do
-  cache key:'writer'
+  cache key:'writer', skip_digest: true
   attributes :id, :name
 
   has_many :posts, embed: :ids
@@ -120,7 +126,7 @@ AuthorSerializer = Class.new(ActiveModel::Serializer) do
 end
 
 RoleSerializer = Class.new(ActiveModel::Serializer) do
-  cache only: [:name]
+  cache only: [:name], skip_digest: true
   attributes :id, :name, :description, :slug
 
   def slug
@@ -137,7 +143,7 @@ LikeSerializer = Class.new(ActiveModel::Serializer) do
 end
 
 LocationSerializer = Class.new(ActiveModel::Serializer) do
-  cache only: [:place]
+  cache only: [:place], skip_digest: true
   attributes :id, :lat, :lng
 
   belongs_to :place
@@ -154,13 +160,14 @@ PlaceSerializer = Class.new(ActiveModel::Serializer) do
 end
 
 BioSerializer = Class.new(ActiveModel::Serializer) do
-  cache except: [:content]
+  cache except: [:content], skip_digest: true
   attributes :id, :content, :rating
 
   belongs_to :author
 end
 
 BlogSerializer = Class.new(ActiveModel::Serializer) do
+  cache key: 'blog'
   attributes :id, :name
 
   belongs_to :writer

test/serializers/cache_test.rb

@@ -5,10 +5,10 @@ module ActiveModel
       def setup
         ActionController::Base.cache_store.clear
         @comment        = Comment.new(id: 1, body: 'ZOMG A COMMENT')
-        @blog           = Blog.new(id: 999, name: "Custom blog")
         @post           = Post.new(title: 'New Post', body: 'Body')
         @bio            = Bio.new(id: 1, content: 'AMS Contributor')
         @author         = Author.new(name: 'Joao M. D. Moura')
+        @blog           = Blog.new(id: 999, name: "Custom blog", writer: @author, articles: [])
         @role           = Role.new(name: 'Great Author')
         @location       = Location.new(lat: '-23.550520', lng: '-46.633309')
         @place          = Place.new(name: 'Amazing Place')
@@ -30,6 +30,7 @@ module ActiveModel
         @post_serializer     = PostSerializer.new(@post)
         @author_serializer   = AuthorSerializer.new(@author)
         @comment_serializer  = CommentSerializer.new(@comment)
+        @blog_serializer     = BlogSerializer.new(@blog)
       end
 
       def test_cache_definition
@@ -56,9 +57,9 @@ module ActiveModel
       end
 
       def test_cache_options_definition
-        assert_equal({expires_in: 0.1}, @post_serializer.class._cache_options)
-        assert_equal(nil, @author_serializer.class._cache_options)
-        assert_equal({expires_in: 1.day}, @comment_serializer.class._cache_options)
+        assert_equal({expires_in: 0.1, skip_digest: true}, @post_serializer.class._cache_options)
+        assert_equal(nil, @blog_serializer.class._cache_options)
+        assert_equal({expires_in: 1.day, skip_digest: true}, @comment_serializer.class._cache_options)
       end
 
       def test_fragment_cache_definition
@@ -115,6 +116,15 @@ module ActiveModel
         assert_equal({place: 'Nowhere'}, ActionController::Base.cache_store.fetch(@location.cache_key))
       end
 
+      def test_uses_file_digest_in_cahe_key
+        blog = render_object_with_cache(@blog)
+        assert_equal(@blog_serializer.attributes, ActionController::Base.cache_store.fetch(@blog.cache_key_with_digest))
+      end
+
+      def _cache_digest_definition
+        assert_equal(::Model::FILE_DIGEST, @post_serializer.class._cache_digest)
+      end
+
       private
       def render_object_with_cache(obj)
         serializer_class = ActiveModel::Serializer.serializer_for(obj)