Add ability to pass a block to Serializer.association

Gemfile

@@ -17,3 +17,5 @@ gem "simplecov-lcov"
 gem "undercover"
 
 gem "pry"
+
+gem "gem-release", require: false

lib/transmutation/serializer.rb

@@ -44,7 +44,7 @@ class << self
       # Define an attribute to be serialized
       #
       # @param attribute_name [Symbol] The name of the attribute to serialize
-      # @param block [Proc] The block to call to get the value of the attribute
+      # @yield [object] The block to call to get the value of the attribute
       #   - The block is called in the context of the serializer instance
       #
       # @example
@@ -66,21 +66,23 @@ def attribute(attribute_name, &block)
       # @param association_name [Symbol] The name of the association to serialize
       # @param namespace [String, Symbol, Module] The namespace to lookup the association's serializer in
       # @param serializer [String, Symbol, Class] The serializer to use for the association's serialization
+      # @yield [object] The block to call to get the value of the association
+      #   - The block is called in the context of the serializer instance
+      #   - The return value from the block is automatically serialized
       #
       # @example
       #   class UserSerializer < Transmutation::Serializer
       #     association :posts
       #     association :comments, namespace: "Nested", serializer: "User::CommentSerializer"
+      #     association :archived_posts do
+      #       object.posts.archived
+      #     end
       #   end
-      def association(association_name, namespace: nil, serializer: nil)
+      def association(association_name, namespace: nil, serializer: nil, &custom_block)
         block = lambda do
-          serialize(
-            object.send(association_name),
-            namespace:,
-            serializer:,
-            depth: @depth + 1,
-            max_depth: @max_depth
-          )
+          association_instance = custom_block ? instance_exec(&custom_block) : object.send(association_name)
+
+          serialize(association_instance, namespace:, serializer:, depth: @depth + 1, max_depth: @max_depth)
         end
 
         attributes_config[association_name] = { block:, association: true }

lib/transmutation/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Transmutation
-  VERSION = "0.4.5"
+  VERSION = "0.5.0"
 end

spec/system/dummy/models/post.rb

@@ -1,13 +1,14 @@
 # frozen_string_literal: true
 
 class Post
-  attr_accessor :id, :title, :body, :user_id
+  attr_accessor :id, :title, :body, :user_id, :published_at
 
-  def initialize(id:, title:, body:, user_id: nil)
+  def initialize(id:, title:, body:, user_id: nil, published_at: nil)
     self.id = id
     self.title = title
     self.body = body
     self.user_id = user_id
+    self.published_at = published_at
   end
 
   def user
@@ -20,9 +21,9 @@ def user
 
   def self.all
     [
-      Post.new(id: 1, title: "First post", body: "First!", user_id: 1),
-      Post.new(id: 2, title: "How does this work?", body: "body", user_id: 2),
-      Post.new(id: 3, title: "Second post!?", body: "Nope...", user_id: 1)
+      Post.new(id: 1, title: "First post", body: "First!", user_id: 1, published_at: Time.now),
+      Post.new(id: 2, title: "How does this work?", body: "body", user_id: 2, published_at: Time.now),
+      Post.new(id: 3, title: "Second post!?", body: "Nope...", user_id: 1, published_at: nil)
     ]
   end
 

spec/system/dummy/serializers/api/v1/detailed/user_serializer.rb

@@ -7,6 +7,10 @@ class UserSerializer < Api::V1::UserSerializer
         attributes :first_name, :last_name
 
         has_many :posts, namespace: "::Api::V1"
+
+        has_many :published_posts, namespace: "::Api::V1" do
+          object.posts.reject { |post| post.published_at.nil? }
+        end
       end
     end
   end

spec/system/rendering_spec.rb

@@ -31,6 +31,9 @@
           "posts" => [
             { "id" => 1, "title" => "First post" },
             { "id" => 3, "title" => "Second post!?" }
+          ],
+          "published_posts" => [
+            { "id" => 1, "title" => "First post" }
           ]
         }
       end