Support overriding association methods

You can override associations to define custom scope on them.

README.md

@@ -146,6 +146,22 @@ call:
 render json: @post, root: "articles"
 ```
 
+### Overriding association methods
+
+If you want to override any association, you can use:
+
+```ruby
+class PostSerializer < ActiveModel::Serializer
+  attributes :id, :body
+
+  has_many :comments
+
+  def comments
+    object.comments.active
+  end
+end
+```
+
 ### Built in Adapters
 
 #### JSONAPI

lib/active_model/serializer.rb

@@ -149,10 +149,12 @@ module ActiveModel
     def each_association(&block)
       self.class._associations.dup.each do |name, options|
         next unless object
+
         association = object.send(name)
+        association_value = send(name)
         serializer_class = ActiveModel::Serializer.serializer_for(association, options)
         serializer = serializer_class.new(
-          association,
+          association_value,
           serializer_from_options(options)
         ) if serializer_class
 

test/action_controller/json_api_linked_test.rb

@@ -29,6 +29,9 @@ module ActionController
           @post2 = Post.new(id: 2, title: "Another Post", body: "Body")
           @post2.author = @author
           @post2.comments = []
+          @blog = Blog.new(id: 1, name: "My Blog!!")
+          @post.blog = @blog
+          @post2.blog = @blog
         end
 
         def render_resource_without_include

test/adapter/json/belongs_to_test.rb

@@ -15,6 +15,9 @@ module ActiveModel
             @comment.post = @post
             @comment.author = nil
             @anonymous_post.author = nil
+            @blog = Blog.new(id: 1, name: "My Blog!!")
+            @post.blog = @blog
+            @anonymous_post.blog = nil
 
             @serializer = CommentSerializer.new(@comment)
             @adapter = ActiveModel::Serializer::Adapter::Json.new(@serializer)
@@ -28,7 +31,7 @@ module ActiveModel
             serializer = PostSerializer.new(@anonymous_post)
             adapter = ActiveModel::Serializer::Adapter::Json.new(serializer)
 
-            assert_equal({title: "Hello!!", body: "Hello, world!!", id: 43, comments: [], author: nil}, adapter.serializable_hash)
+            assert_equal({title: "Hello!!", body: "Hello, world!!", id: 43, comments: [], blog: nil, author: nil}, adapter.serializable_hash)
           end
         end
       end

test/adapter/json/collection_test.rb

@@ -13,16 +13,40 @@ module ActiveModel
             @second_post.comments = []
             @first_post.author = @author
             @second_post.author = @author
+            @blog = Blog.new(id: 1, name: "My Blog!!")
+            @first_post.blog = @blog
+            @second_post.blog = nil
 
             @serializer = ArraySerializer.new([@first_post, @second_post])
             @adapter = ActiveModel::Serializer::Adapter::Json.new(@serializer)
           end
 
           def test_include_multiple_posts
-            assert_equal([
+            expected = [{
-                           {title: "Hello!!", body: "Hello, world!!", id: 1, comments: [], author: {id: 1, name: "Steve K."}},
+              title: "Hello!!",
-                           {title: "New Post", body: "Body", id: 2, comments: [], author: {id: 1, name: "Steve K."}}
+              body: "Hello, world!!",
-                         ], @adapter.serializable_hash)
+              id: 1,
+              comments: [],
+              author: {
+                id: 1,
+                name: "Steve K."
+              },
+              blog: {
+                id: 999,
+                name: "Custom blog"
+              }
+            }, {
+              title: "New Post",
+              body: "Body",
+              id: 2,
+              comments: [],
+              author: {
+                id: 1,
+                name: "Steve K."
+              },
+              blog: nil
+            }]
+            assert_equal expected, @adapter.serializable_hash
           end
         end
       end

test/adapter/json/has_many_test.rb

@@ -14,6 +14,8 @@ module ActiveModel
             @post.author = @author
             @first_comment.post = @post
             @second_comment.post = @post
+            @blog = Blog.new(id: 1, name: "My Blog!!")
+            @post.blog = @blog
 
             @serializer = PostSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::Json.new(@serializer)

test/adapter/json_api/belongs_to_test.rb

@@ -9,11 +9,14 @@ module ActiveModel
             @author = Author.new(id: 1, name: 'Steve K.')
             @author.bio = nil
             @author.roles = []
+            @blog = Blog.new(id: 23, name: 'AMS Blog')
             @post = Post.new(id: 42, title: 'New Post', body: 'Body')
             @anonymous_post = Post.new(id: 43, title: 'Hello!!', body: 'Hello, world!!')
             @comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
             @post.comments = [@comment]
+            @post.blog = @blog
             @anonymous_post.comments = []
+            @anonymous_post.blog = nil
             @comment.post = @post
             @comment.author = nil
             @post.author = @author
@@ -39,6 +42,7 @@ module ActiveModel
               body: 'Body',
               links: {
                 comments: ["1"],
+                blog: "999",
                 author: "1"
               }
             }]
@@ -51,6 +55,7 @@ module ActiveModel
               title: 'New Post',
               links: {
                 comments: ["1"],
+                blog: "999",
                 author: "1"
               }
             }]
@@ -61,7 +66,7 @@ module ActiveModel
             serializer = PostSerializer.new(@anonymous_post)
             adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
 
-            assert_equal({comments: [], author: nil}, adapter.serializable_hash[:posts][:links])
+            assert_equal({comments: [], blog: nil, author: nil}, adapter.serializable_hash[:posts][:links])
           end
 
           def test_include_type_for_association_when_different_than_name
@@ -101,6 +106,7 @@ module ActiveModel
                 id: "42",
                 links: {
                   comments: ["1"],
+                  blog: "999",
                   author: "1"
                 }
               }, {
@@ -109,6 +115,7 @@ module ActiveModel
                 id: "43",
                 links: {
                   comments: [],
+                  blog: nil,
                   author: nil
                 }
               }]

test/adapter/json_api/collection_test.rb

@@ -8,10 +8,13 @@ module ActiveModel
           def setup
             @author = Author.new(id: 1, name: 'Steve K.')
             @author.bio = nil
+            @blog = Blog.new(id: 23, name: 'AMS Blog')
             @first_post = Post.new(id: 1, title: 'Hello!!', body: 'Hello, world!!')
             @second_post = Post.new(id: 2, title: 'New Post', body: 'Body')
             @first_post.comments = []
             @second_post.comments = []
+            @first_post.blog = @blog
+            @second_post.blog = nil
             @first_post.author = @author
             @second_post.author = @author
             @author.posts = [@first_post, @second_post]
@@ -22,16 +25,16 @@ module ActiveModel
 
           def test_include_multiple_posts
             assert_equal([
-                           { title: "Hello!!", body: "Hello, world!!", id: "1", links: { comments: [], author: "1" } },
+                           { title: "Hello!!", body: "Hello, world!!", id: "1", links: { comments: [], blog: "999", author: "1" } },
-                           { title: "New Post", body: "Body", id: "2", links: { comments: [], author: "1" } }
+                           { title: "New Post", body: "Body", id: "2", links: { comments: [], blog: nil, author: "1" } }
                          ], @adapter.serializable_hash[:posts])
           end
 
           def test_limiting_fields
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, fields: ['title'])
             assert_equal([
-              { title: "Hello!!", links: { comments: [], author: "1" } },
+              { title: "Hello!!", links: { comments: [], blog: "999", author: "1" } },
-              { title: "New Post", links: { comments: [], author: "1" } }
+              { title: "New Post", links: { comments: [], blog: nil, author: "1" } }
             ], @adapter.serializable_hash[:posts])
           end
 

test/adapter/json_api/has_many_embed_ids_test.rb

@@ -16,6 +16,9 @@ module ActiveModel
             @second_post.author = @author
             @first_post.comments = []
             @second_post.comments = []
+            @blog = Blog.new(id: 23, name: 'AMS Blog')
+            @first_post.blog = @blog
+            @second_post.blog = nil
 
             @serializer = AuthorSerializer.new(@author)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)

test/adapter/json_api/has_many_explicit_serializer_test.rb

@@ -18,6 +18,8 @@ module ActiveModel
             @first_comment.author = nil
             @second_comment.post = @post
             @second_comment.author = nil
+            @blog = Blog.new(id: 23, name: 'AMS Blog')
+            @post.blog = @blog
 
             @serializer = PostPreviewSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(

test/adapter/json_api/has_many_test.rb

@@ -24,6 +24,8 @@ module ActiveModel
             @blog = Blog.new(id: 1, name: "My Blog!!")
             @blog.writer = @author
             @blog.articles = [@post]
+            @post.blog = @blog
+            @post_without_comments.blog = nil
 
             @serializer = PostSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
@@ -32,7 +34,7 @@ module ActiveModel
           def test_includes_comment_ids
             assert_equal(["1", "2"], @adapter.serializable_hash[:posts][:links][:comments])
           end
-          
+
           def test_includes_linked_comments
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, include: 'comments')
             expected = [{

test/adapter/json_api/linked_test.rb

@@ -13,6 +13,10 @@ module ActiveModel
             @first_post = Post.new(id: 1, title: 'Hello!!', body: 'Hello, world!!')
             @second_post = Post.new(id: 2, title: 'New Post', body: 'Body')
             @third_post = Post.new(id: 3, title: 'Yet Another Post', body: 'Body')
+            @blog = Blog.new({ name: 'AMS Blog' })
+            @first_post.blog = @blog
+            @second_post.blog = @blog
+            @third_post.blog = nil
             @first_post.comments = []
             @second_post.comments = []
             @first_post.author = @author1
@@ -124,6 +128,7 @@ module ActiveModel
                 id: "1",
                 links: {
                   comments: ["1", "2"],
+                  blog: "999",
                   author: "1"
                 }
               }, {
@@ -132,6 +137,7 @@ module ActiveModel
                 id: "3",
                 links: {
                   comments: [],
+                  blog: nil,
                   author: "1"
                 }
               }]

test/adapter/json_test.rb

@@ -13,6 +13,8 @@ module ActiveModel
           @first_comment.post = @post
           @second_comment.post = @post
           @post.author = @author
+          @blog = Blog.new(id: 1, name: "My Blog!!")
+          @post.blog = @blog
 
           @serializer = PostSerializer.new(@post)
           @adapter = ActiveModel::Serializer::Adapter::Json.new(@serializer)

test/fixtures/poro.rb

@@ -54,8 +54,13 @@ PostSerializer = Class.new(ActiveModel::Serializer) do
   attributes :title, :body, :id
 
   has_many :comments
+  belongs_to :blog
   belongs_to :author
   url :comments
+
+  def blog
+    Blog.new(id: 999, name: "Custom blog")
+  end
 end
 
 SpammyPostSerializer = Class.new(ActiveModel::Serializer) do

test/serializers/associations_test.rb

@@ -28,14 +28,17 @@ module ActiveModel
         @author = Author.new(name: 'Steve K.')
         @author.bio = nil
         @author.roles = []
+        @blog = Blog.new({ name: 'AMS Blog' })
         @post = Post.new({ title: 'New Post', body: 'Body' })
         @comment = Comment.new({ id: 1, body: 'ZOMG A COMMENT' })
         @post.comments = [@comment]
+        @post.blog = @blog
         @comment.post = @post
         @comment.author = nil
         @post.author = @author
         @author.posts = [@post]
 
+        @post_serializer = PostSerializer.new(@post)
         @author_serializer = AuthorSerializer.new(@author)
         @comment_serializer = CommentSerializer.new(@comment)
       end
@@ -63,7 +66,7 @@ module ActiveModel
         end
       end
 
-      def test_has_one
+      def test_belongs_to
         assert_equal({post: {type: :belongs_to, association_options: {}}, :author=>{:type=>:belongs_to, :association_options=>{}}}, @comment_serializer.class._associations)
         @comment_serializer.each_association do |name, serializer, options|
           if name == :post
@@ -77,6 +80,16 @@ module ActiveModel
           end
         end
       end
+
+      def test_belongs_to_with_custom_method
+        blog_is_present = false
+
+        @post_serializer.each_association do |name, serializer, options|
+          blog_is_present = true if name == :blog
+        end
+
+        assert blog_is_present
+      end
     end
   end
 end