From cc109284725b35977dd16ea2279c882a25114c5d Mon Sep 17 00:00:00 2001
From: Ben Mills <ben@unfiniti.com>
Date: Tue, 1 Mar 2016 19:23:55 -0700
Subject: [PATCH] Provide Rails url_helpers via SerializationContext

---
 CHANGELOG.md                                  |  2 +
 Rakefile                                      | 30 +++++-----
 docs/general/getting_started.md               |  9 +++
 docs/general/rendering.md                     | 32 +++++++++-
 docs/general/serializers.md                   | 10 ++--
 lib/active_model/serializer/links.rb          |  6 +-
 .../adapter/json_api/link.rb                  |  5 ++
 lib/active_model_serializers/railtie.rb       |  5 ++
 .../serialization_context.rb                  | 16 ++++-
 .../railtie_test_isolated.rb                  |  6 ++
 .../serialization_context_test.rb             | 18 ------
 .../serialization_context_test_isolated.rb    | 58 +++++++++++++++++++
 test/adapter/json_api/links_test.rb           | 29 ++++++----
 test/support/isolated_unit.rb                 |  1 +
 test/support/rails_app.rb                     |  2 +
 15 files changed, 177 insertions(+), 52 deletions(-)
 delete mode 100644 test/active_model_serializers/serialization_context_test.rb
 create mode 100644 test/active_model_serializers/serialization_context_test_isolated.rb

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1466f340c..972be1252 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,8 @@
 Breaking changes:
 
 Features:
+- [#1550](https://github.com/rails-api/active_model_serializers/pull/1550) Add
+  Rails url_helpers to `SerializationContext` for use in links. (@remear, @bf4)
 - [#1004](https://github.com/rails-api/active_model_serializers/pull/1004) JSON API errors object implementation.
   - Only implements `detail` and `source` as derived from `ActiveModel::Error`
   - Provides checklist of remaining questions and remaining parts of the spec.
diff --git a/Rakefile b/Rakefile
index 94de4fe5e..04c28a1a8 100644
--- a/Rakefile
+++ b/Rakefile
@@ -45,25 +45,23 @@ Rake::TestTask.new do |t|
 end
 
 desc 'Run isolated tests'
-task isolated: ['test:isolated:railtie']
+task isolated: ['test:isolated']
 namespace :test do
-  namespace :isolated do
+  task :isolated do
     desc 'Run isolated tests for Railtie'
-    task :railtie do
-      require 'shellwords'
-      dir = File.dirname(__FILE__)
-      file = Shellwords.shellescape("#{dir}/test/active_model_serializers/railtie_test_isolated.rb")
-      dir = Shellwords.shellescape(dir)
-
-      # https://github.com/rails/rails/blob/3d590add45/railties/lib/rails/generators/app_base.rb#L345-L363
-      _bundle_command = Gem.bin_path('bundler', 'bundle')
-      require 'bundler'
-      Bundler.with_clean_env do
-        command = "-w -I#{dir}/lib -I#{dir}/test #{file}"
+    require 'shellwords'
+    dir = File.dirname(__FILE__)
+    dir = Shellwords.shellescape(dir)
+    isolated_test_files = FileList['test/**/*_test_isolated.rb']
+    # https://github.com/rails/rails/blob/3d590add45/railties/lib/rails/generators/app_base.rb#L345-L363
+    _bundle_command = Gem.bin_path('bundler', 'bundle')
+    require 'bundler'
+    Bundler.with_clean_env do
+      isolated_test_files.all? do |test_file|
+        command = "-w -I#{dir}/lib -I#{dir}/test #{Shellwords.shellescape(test_file)}"
         full_command = %("#{Gem.ruby}" #{command})
-        system(full_command) or # rubocop:disable Style/AndOr
-          fail 'Failures'
-      end
+        system(full_command)
+      end or fail 'Failures' # rubocop:disable Style/AndOr
     end
   end
 end
diff --git a/docs/general/getting_started.md b/docs/general/getting_started.md
index cd207159a..d9d08ae35 100644
--- a/docs/general/getting_started.md
+++ b/docs/general/getting_started.md
@@ -96,3 +96,12 @@ class PostsController < ApplicationController
 
 end
 ```
+
+If you wish to use Rails url helpers for link generation, e.g., `link(:resources) { resources_url }`, ensure your application sets
+`Rails.application.routes.default_url_options`.
+
+```ruby
+Rails.application.routes.default_url_options = {
+    host: 'example.com'
+}
+```
diff --git a/docs/general/rendering.md b/docs/general/rendering.md
index b83493257..0f79321f7 100644
--- a/docs/general/rendering.md
+++ b/docs/general/rendering.md
@@ -103,7 +103,10 @@ PR please :)
 
 #### links
 
-##### How to add top-level links
+If you wish to use Rails url helpers for link generation, e.g., `link(:resources) { resources_url }`, ensure your application sets
+`Rails.application.routes.default_url_options`.
+
+##### Top-level
 
 JsonApi supports a [links object](http://jsonapi.org/format/#document-links) to be specified at top-level, that you can specify in the `render`:
 
@@ -144,6 +147,33 @@ That's the result:
 
 This feature is specific to JsonApi, so you have to use the use the [JsonApi Adapter](adapters.md#jsonapi)
 
+
+##### Resource-level
+
+In your serializer, define each link in one of the following methods:
+
+As a static string
+
+```ruby
+link :link_name, 'https://example.com/resource'
+```
+
+As a block to be evaluated. When using Rails, URL helpers are available.
+Ensure your application sets `Rails.application.routes.default_url_options`.
+
+```ruby
+link :link_name_ do
+  "https://example.com/resource/#{object.id}"
+end
+
+link(:link_name) { "https://example.com/resource/#{object.id}" }
+
+link(:link_name) { resource_url(object) }
+
+link(:link_name) { url_for(controller: 'controller_name', action: 'index', only_path: false) }
+
+```
+
 ### serializer_opts
 
 #### include
diff --git a/docs/general/serializers.md b/docs/general/serializers.md
index 65ccaa1a7..d4a9e757b 100644
--- a/docs/general/serializers.md
+++ b/docs/general/serializers.md
@@ -135,13 +135,15 @@ With the `:json_api` adapter, the previous serializers would be rendered as:
 
 #### ::link
 
-e.g.
-
 ```ruby
-link :other, 'https://example.com/resource'
 link :self do
- href "https://example.com/link_author/#{object.id}"
+  href "https://example.com/link_author/#{object.id}"
 end
+link :author { link_author_url(object) }
+link :link_authors { link_authors_url }
+link :other, 'https://example.com/resource'
+link :posts { link_author_posts_url(object) }
+```
 ```
 
 #### #object
diff --git a/lib/active_model/serializer/links.rb b/lib/active_model/serializer/links.rb
index c079d4e17..1322adb0a 100644
--- a/lib/active_model/serializer/links.rb
+++ b/lib/active_model/serializer/links.rb
@@ -20,9 +20,11 @@ def inherited(base)
 
         # Define a link on a serializer.
         # @example
-        #   link :self { "//example.com/posts/#{object.id}" }
+        #   link(:self) { resource_url(object) }
         # @example
-        #   link :self, "//example.com/user"
+        #   link(:self) { "http://example.com/resource/#{object.id}" }
+        # @example
+        #   link :resource, "http://example.com/resource"
         #
         def link(name, value = nil, &block)
           _links[name] = block || value
diff --git a/lib/active_model_serializers/adapter/json_api/link.rb b/lib/active_model_serializers/adapter/json_api/link.rb
index 3408a98e2..255f875a5 100644
--- a/lib/active_model_serializers/adapter/json_api/link.rb
+++ b/lib/active_model_serializers/adapter/json_api/link.rb
@@ -1,7 +1,12 @@
+require 'active_support/core_ext/module/delegation'
+
 module ActiveModelSerializers
   module Adapter
     class JsonApi
       class Link
+        include SerializationContext.url_helpers
+        delegate :default_url_options, to: SerializationContext
+
         def initialize(serializer, value)
           @object = serializer.object
           @scope = serializer.scope
diff --git a/lib/active_model_serializers/railtie.rb b/lib/active_model_serializers/railtie.rb
index 6572d9d1e..1d95ceac7 100644
--- a/lib/active_model_serializers/railtie.rb
+++ b/lib/active_model_serializers/railtie.rb
@@ -15,6 +15,11 @@ class Railtie < Rails::Railtie
       end
     end
 
+    initializer 'active_model_serializers.prepare_serialization_context' do
+      SerializationContext.url_helpers = Rails.application.routes.url_helpers
+      SerializationContext.default_url_options = Rails.application.routes.default_url_options
+    end
+
     # This hook is run after the action_controller railtie has set the configuration
     # based on the *environment* configuration and before any config/initializers are run
     # and also before eager_loading (if enabled).
diff --git a/lib/active_model_serializers/serialization_context.rb b/lib/active_model_serializers/serialization_context.rb
index a373d6869..d7f8aba9e 100644
--- a/lib/active_model_serializers/serialization_context.rb
+++ b/lib/active_model_serializers/serialization_context.rb
@@ -1,10 +1,24 @@
 module ActiveModelSerializers
   class SerializationContext
+    class << self
+      attr_writer :url_helpers, :default_url_options
+    end
+
     attr_reader :request_url, :query_parameters
 
-    def initialize(request)
+    def initialize(request, options = {})
       @request_url = request.original_url[/\A[^?]+/]
       @query_parameters = request.query_parameters
+      @url_helpers = options.delete(:url_helpers) || self.class.url_helpers
+      @default_url_options = options.delete(:default_url_options) || self.class.default_url_options
+    end
+
+    def self.url_helpers
+      @url_helpers ||= Module.new
+    end
+
+    def self.default_url_options
+      @default_url_options ||= {}
     end
   end
 end
diff --git a/test/active_model_serializers/railtie_test_isolated.rb b/test/active_model_serializers/railtie_test_isolated.rb
index 2e2818ed6..21f6c178e 100644
--- a/test/active_model_serializers/railtie_test_isolated.rb
+++ b/test/active_model_serializers/railtie_test_isolated.rb
@@ -18,6 +18,12 @@ class WithRails < RailtieTest
         "ActionController::Serialization should be included in ActionController::Base, but isn't"
     end
 
+    test 'prepares url_helpers for SerializationContext' do
+      assert ActiveModelSerializers::SerializationContext.url_helpers.respond_to? :url_for
+      assert_equal Rails.application.routes.default_url_options,
+        ActiveModelSerializers::SerializationContext.default_url_options
+    end
+
     test 'sets the ActiveModelSerializers.logger to Rails.logger' do
       refute_nil Rails.logger
       refute_nil ActiveModelSerializers.logger
diff --git a/test/active_model_serializers/serialization_context_test.rb b/test/active_model_serializers/serialization_context_test.rb
deleted file mode 100644
index 940e65e5a..000000000
--- a/test/active_model_serializers/serialization_context_test.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require 'test_helper'
-
-class ActiveModelSerializers::SerializationContextTest < ActiveSupport::TestCase
-  def create_context
-    request = Minitest::Mock.new
-    request.expect(:original_url, 'original_url')
-    request.expect(:query_parameters, 'query_parameters')
-
-    ActiveModelSerializers::SerializationContext.new(request)
-  end
-
-  def test_create_context_with_request_url_and_query_parameters
-    context = create_context
-
-    assert_equal context.request_url, 'original_url'
-    assert_equal context.query_parameters, 'query_parameters'
-  end
-end
diff --git a/test/active_model_serializers/serialization_context_test_isolated.rb b/test/active_model_serializers/serialization_context_test_isolated.rb
new file mode 100644
index 000000000..981d80752
--- /dev/null
+++ b/test/active_model_serializers/serialization_context_test_isolated.rb
@@ -0,0 +1,58 @@
+# Execute this test in isolation
+require 'support/isolated_unit'
+require 'minitest/mock'
+
+class SerializationContextTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::Isolation
+
+  def create_request
+    request = Minitest::Mock.new
+    request.expect(:original_url, 'original_url')
+    request.expect(:query_parameters, 'query_parameters')
+  end
+
+  class WithRails < SerializationContextTest
+    setup do
+      require 'rails'
+      require 'active_model_serializers'
+      make_basic_app
+      @context = ActiveModelSerializers::SerializationContext.new(create_request)
+    end
+
+    test 'create context with request url and query parameters' do
+      assert_equal @context.request_url, 'original_url'
+      assert_equal @context.query_parameters, 'query_parameters'
+    end
+
+    test 'url_helpers is set up for Rails url_helpers' do
+      assert_equal Module, ActiveModelSerializers::SerializationContext.url_helpers.class
+      assert ActiveModelSerializers::SerializationContext.url_helpers.respond_to? :url_for
+    end
+
+    test 'default_url_options returns Rails.application.routes.default_url_options' do
+      assert_equal Rails.application.routes.default_url_options,
+        ActiveModelSerializers::SerializationContext.default_url_options
+    end
+  end
+
+  class WithoutRails < SerializationContextTest
+    setup do
+      require 'active_model_serializers/serialization_context'
+      @context = ActiveModelSerializers::SerializationContext.new(create_request)
+    end
+
+    test 'create context with request url and query parameters' do
+      assert_equal @context.request_url, 'original_url'
+      assert_equal @context.query_parameters, 'query_parameters'
+    end
+
+    test 'url_helpers is a module when Rails is not present' do
+      assert_equal Module, ActiveModelSerializers::SerializationContext.url_helpers.class
+      refute ActiveModelSerializers::SerializationContext.url_helpers.respond_to? :url_for
+    end
+
+    test 'default_url_options return a Hash' do
+      assert Hash, ActiveModelSerializers::SerializationContext.default_url_options.class
+    end
+  end
+end
diff --git a/test/adapter/json_api/links_test.rb b/test/adapter/json_api/links_test.rb
index 09c499ed3..87f22644d 100644
--- a/test/adapter/json_api/links_test.rb
+++ b/test/adapter/json_api/links_test.rb
@@ -7,18 +7,24 @@ class LinksTest < ActiveSupport::TestCase
         LinkAuthor = Class.new(::Model)
         class LinkAuthorSerializer < ActiveModel::Serializer
           link :self do
-            href "//example.com/link_author/#{object.id}"
+            href "http://example.com/link_author/#{object.id}"
             meta stuff: 'value'
           end
-
-          link :other, '//example.com/resource'
-
+          link(:author) { link_author_url(object.id) }
+          link(:link_authors) { url_for(controller: 'link_authors', action: 'index', only_path: false) }
+          link(:posts) { link_author_posts_url(object.id) }
+          link :resource, 'http://example.com/resource'
           link :yet_another do
-            "//example.com/resource/#{object.id}"
+            "http://example.com/resource/#{object.id}"
           end
         end
 
         def setup
+          Rails.application.routes.draw do
+            resources :link_authors do
+              resources :posts
+            end
+          end
           @post = Post.new(id: 1337, comments: [], author: nil)
           @author = LinkAuthor.new(id: 1337, posts: [@post])
         end
@@ -29,7 +35,7 @@ def test_toplevel_links
             adapter: :json_api,
             links: {
               self: {
-                href: '//example.com/posts',
+                href: 'http://example.com/posts',
                 meta: {
                   stuff: 'value'
                 }
@@ -37,7 +43,7 @@ def test_toplevel_links
             }).serializable_hash
           expected = {
             self: {
-              href: '//example.com/posts',
+              href: 'http://example.com/posts',
               meta: {
                 stuff: 'value'
               }
@@ -68,13 +74,16 @@ def test_resource_links
           hash = serializable(@author, adapter: :json_api).serializable_hash
           expected = {
             self: {
-              href: '//example.com/link_author/1337',
+              href: 'http://example.com/link_author/1337',
               meta: {
                 stuff: 'value'
               }
             },
-            other: '//example.com/resource',
-            yet_another: '//example.com/resource/1337'
+            author: 'http://example.com/link_authors/1337',
+            link_authors: 'http://example.com/link_authors',
+            resource: 'http://example.com/resource',
+            posts: 'http://example.com/link_authors/1337/posts',
+            yet_another: 'http://example.com/resource/1337'
           }
           assert_equal(expected, hash[:data][:links])
         end
diff --git a/test/support/isolated_unit.rb b/test/support/isolated_unit.rb
index 50362239d..34f186618 100644
--- a/test/support/isolated_unit.rb
+++ b/test/support/isolated_unit.rb
@@ -63,6 +63,7 @@ def make_basic_app
         # Set a fake logger to avoid creating the log directory automatically
         fake_logger = Logger.new(nil)
         config.logger = fake_logger
+        Rails.application.routes.default_url_options = { host: 'example.com' }
       end
       @app.respond_to?(:secrets) && @app.secrets.secret_key_base = '3b7cd727ee24e8444053437c36cc66c4'
 
diff --git a/test/support/rails_app.rb b/test/support/rails_app.rb
index ced830dc5..7f74e4ba1 100644
--- a/test/support/rails_app.rb
+++ b/test/support/rails_app.rb
@@ -10,6 +10,8 @@ class ActiveModelSerializers::RailsApplication < Rails::Application
 
     config.action_controller.perform_caching = true
     ActionController::Base.cache_store = :memory_store
+
+    Rails.application.routes.default_url_options = { host: 'example.com' }
   end
 end
 ActiveModelSerializers::RailsApplication.initialize!