Add pagination links automatically

Pagination links will be included in your response automatically as long
as the resource is paginated using Kaminari or WillPaginate
and if you are using a JSON-API adapter. The others adapters does not have this feature.

Author: bacarini

README.md

@@ -118,7 +118,7 @@ If you wish to use a serializer other than the default, you can explicitly pass
 render json: @posts, each_serializer: PostPreviewSerializer
 
 # Or, you can explicitly provide the collection serializer as well
-render json: @posts, serializer: PaginatedSerializer, each_serializer: PostPreviewSerializer
+render json: @posts, serializer: CollectionSerializer, each_serializer: PostPreviewSerializer
 ```
 
 ### Meta
@@ -272,6 +272,11 @@ And you can change the JSON key that the serializer should use for a particular
 
 The `url` declaration describes which named routes to use while generating URLs
 for your JSON. Not every adapter will require URLs.
+## Pagination
+
+Pagination links will be included in your response automatically as long as the resource is paginated using [Kaminari](https://github.com/amatsuda/kaminari) or [WillPaginate](https://github.com/mislav/will_paginate) and if you are using a ```JSON-API``` adapter. The others adapters does not have this feature.
+
+For more information about it, please see in our docs [How to add pagination links](https://github.com/rails-api/active_model_serializers/blob/master/docs/howto/add_pagination_links.md)
 
 ## Caching
 

docs/howto/add_pagination_links.md

@@ -1,14 +1,18 @@
 # How to add pagination links
 
-If you want pagination links in your response, specify it in the `render`
+Pagination links will be included in your response automatically as long as the resource is paginated and if you are using a ```JSON-API``` adapter. The others adapters does not have this feature.
 
-```ruby
-  render json: @posts, pagination: true
-```
+If you want pagination links in your response, use [Kaminari](https://github.com/amatsuda/kaminari) or [WillPaginate](https://github.com/mislav/will_paginate).
 
-AMS relies on either `Kaminari` or `WillPaginate`. Please install either dependency by adding one of those to your Gemfile.
+```ruby
+#kaminari example
+@posts = Kaminari.paginate_array(Post.all).page(3).per(1)
+render json: @posts
 
-Pagination links will only be included in your response if you are using a ```JSON-API``` adapter, the others adapters doesn't have this feature.
+#will_paginate example
+@posts = Post.all.paginate(page: 3, per_page: 1)
+render json: @posts
+```
 
 ```ruby
 ActiveModel::Serializer.config.adapter = :json_api
@@ -38,3 +42,5 @@ ex:
   }
 }
 ```
+
+AMS relies on either [Kaminari](https://github.com/amatsuda/kaminari) or [WillPaginate](https://github.com/mislav/will_paginate). Please install either dependency by adding one of those to your Gemfile.

lib/action_controller/serialization.rb

@@ -25,9 +25,10 @@ def get_serializer(resource, options = {})
           "Please pass 'adapter: false' or see ActiveSupport::SerializableResource#serialize"
         options[:adapter] = false
       end
-      if options[:pagination]
-        options[:original_url] = original_url
-        options[:query_parameters] = query_parameters
+      if resource.respond_to?(:current_page) && resource.respond_to?(:total_pages)
+        options[:pagination] = {}
+        options[:pagination][:original_url] = original_url
+        options[:pagination][:query_parameters] = query_parameters
       end
       ActiveModel::SerializableResource.serialize(resource, options) do |serializable_resource|
         if serializable_resource.serializer?

lib/active_model/serializable_resource.rb

@@ -2,7 +2,7 @@
 module ActiveModel
   class SerializableResource
 
-    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter, :pagination])
+    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter])
 
     def initialize(resource, options = {})
       @resource = resource

lib/active_model/serializer/adapter/json_api.rb

@@ -164,7 +164,7 @@ def add_resource_relationships(attrs, serializer, options = {})
         def add_links(options)
           links = @hash.fetch(:links) { {} }
           resources = serializer.instance_variable_get(:@resource)
-          @hash[:links] = add_pagination_links(links, resources, options) if @options[:pagination]
+          @hash[:links] = add_pagination_links(links, resources, options) if options[:pagination]
         end
 
         def add_pagination_links(links, resources, options)

lib/active_model/serializer/adapter/json_api/pagination_links.rb

@@ -14,7 +14,7 @@ def initialize(collection)
 
           def serializable_hash(options = {})
             pages_from.each_with_object({}) do |(key, value), hash|
-              query_parameters = options.fetch(:query_parameters) { {} }
+              query_parameters = options[:pagination].fetch(:query_parameters) { {} }
               params = query_parameters.merge(page: { number: value, size: collection.size }).to_query
 
               hash[key] = "#{url(options)}?#{params}"
@@ -51,7 +51,7 @@ def raise_unless_any_gem_installed
 
           def url(options)
             self_link = options.fetch(:links) {{}}
-            self_link.fetch(:self) {} ? options[:links][:self] : options[:original_url]
+            self_link.fetch(:self) {} ? options[:links][:self] : options[:pagination][:original_url]
           end
         end
       end

test/action_controller/json_api/pagination_test.rb

@@ -31,19 +31,16 @@ def using_will_paginate
           end
 
           def render_pagination_using_kaminari
-            render json: using_kaminari, adapter: :json_api, pagination: true
+            render json: using_kaminari, adapter: :json_api
           end
 
           def render_pagination_using_will_paginate
-            render json: using_will_paginate, adapter: :json_api, pagination: true
+            render json: using_will_paginate, adapter: :json_api
           end
 
           def render_array_without_pagination_links
-            render json: using_will_paginate, adapter: :json_api, pagination: false
-          end
-
-          def render_array_omitting_pagination_options
-            render json: using_kaminari, adapter: :json_api
+            setup
+            render json: @array, adapter: :json_api
           end
         end
 
@@ -104,12 +101,6 @@ def test_array_without_pagination_links
           response = JSON.parse(@response.body)
           refute response.key? 'links'
         end
-
-        def test_array_omitting_pagination_options
-          get :render_array_omitting_pagination_options, page: { number: 2, size: 1 }
-          response = JSON.parse(@response.body)
-          refute response.key? 'links'
-        end
       end
     end
   end

test/adapter/json_api/pagination_links_test.rb

@@ -27,15 +27,11 @@ def using_will_paginate
           end
 
           def data
-            {
-              data: [{
-                id:"2",
-                type:"profiles",
-                attributes:{
-                  name:"Name 2",
-                  description:"Description 2"
-                }
-              }]
+            { data:[
+                { id:"1", type:"profiles", attributes:{name:"Name 1", description:"Description 1" } },
+                { id:"2", type:"profiles", attributes:{name:"Name 2", description:"Description 2" } },
+                { id:"3", type:"profiles", attributes:{name:"Name 3", description:"Description 3" } }
+              ]
             }
           end
 
@@ -56,42 +52,48 @@ def expected_response_without_pagination_links
           end
 
           def expected_response_with_pagination_links
-            data.merge links
+            {}.tap do |hash|
+              hash[:data] = [data.values.flatten.second]
+              hash.merge! links
+            end
           end
 
           def expected_response_with_pagination_links_and_additional_params
             new_links = links[:links].each_with_object({}) {|(key, value), hash| hash[key] = "#{value}&teste=teste" }
-            data.merge links: new_links
+            {}.tap do |hash|
+              hash[:data] = [data.values.flatten.second]
+              hash.merge! links: new_links
+            end
           end
 
           def test_pagination_links_using_kaminari
             serializer = ArraySerializer.new(using_kaminari)
-            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer, pagination: true)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
 
             assert_equal expected_response_with_pagination_links,
-              adapter.serializable_hash(original_url: "http://example.com")
+              adapter.serializable_hash(pagination: { original_url: "http://example.com" })
           end
 
           def test_pagination_links_using_will_paginate
             serializer = ArraySerializer.new(using_will_paginate)
-            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer, pagination: true)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
 
             assert_equal expected_response_with_pagination_links,
-              adapter.serializable_hash(original_url: "http://example.com")
+              adapter.serializable_hash(pagination: { original_url: "http://example.com" })
           end
 
           def test_pagination_links_with_additional_params
             serializer = ArraySerializer.new(using_will_paginate)
-            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer, pagination: true)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
             assert_equal expected_response_with_pagination_links_and_additional_params,
-              adapter.serializable_hash(original_url: "http://example.com",
-                                        query_parameters: { teste: "teste"})
+              adapter.serializable_hash(pagination: { original_url: "http://example.com",
+                                        query_parameters: { teste: "teste"}})
 
           end
 
           def test_not_showing_pagination_links
-            serializer = ArraySerializer.new(using_will_paginate)
-            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer, pagination: false)
+            serializer = ArraySerializer.new(@array)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
 
             assert_equal expected_response_without_pagination_links, adapter.serializable_hash
           end