Add config for disabling JsonApi automatic pagination

The following configuration can now be used to disable automatic
pagination links when using JsonApi adapter:
ActiveModelSerializer.config.collection_serializer =
  ActiveModel::Serializer::Nonpaginatedcollectionserializer

Author: Yohan Robert

docs/howto/add_pagination_links.md

@@ -2,47 +2,34 @@
 
 # How to add pagination links
 
-### JSON API adapter
+## JSON API adapter
 
-Pagination links will be included in your response automatically as long as
-the resource is paginated and if you are using the ```JsonApi``` adapter.
+When using the `JsonApi` adapter, pagination links will be automatically included if you use [Kaminari](https://github.com/amatsuda/kaminari)
+or [WillPaginate](https://github.com/mislav/will_paginate) within a Rails controller:
 
-If you want pagination links in your response, use [Kaminari](https://github.com/amatsuda/kaminari)
-or [WillPaginate](https://github.com/mislav/will_paginate).
-
-Although the others adapters does not have this feature, it is possible to
-implement pagination links to `JSON` adapter. For more information about it,
-please see in our docs 
-
-###### Kaminari examples
+* Using Kaminari:
 
 ```ruby
-#array
-@posts = Kaminari.paginate_array([1, 2, 3]).page(3).per(1)
-render json: @posts
-
-#active_record
-@posts = Post.page(3).per(1)
-render json: @posts
+class PostsController < ApplicationController
+  def index
+    posts = Post.page(params[:page]).per(params[:per_page])
+    render json: posts
+  end
+end
 ```
 
-###### WillPaginate examples
-
-```ruby
-#array
-@posts = [1,2,3].paginate(page: 3, per_page: 1)
-render json: @posts
-
-#active_record
-@posts = Post.page(3).per_page(1)
-render json: @posts
-```
+* Using WillPaginate:
 
 ```ruby
-ActiveModelSerializers.config.adapter = :json_api
+class PostsController < ApplicationController
+  def index
+    posts = Post.page(params[:page]).per_page(params[:per_page])
+    render json: posts
+  end
+end
 ```
 
-ex:
+The response might look like:
 ```json
 {
   "data": [
@@ -67,34 +54,50 @@ ex:
 }
 ```
 
-ActiveModelSerializers pagination relies on a paginated collection with the methods `current_page`, `total_pages`, and `size`, such as are supported by both [Kaminari](https://github.com/amatsuda/kaminari) or [WillPaginate](https://github.com/mislav/will_paginate).
-
+ActiveModelSerializers pagination relies on paginated collections which define the methods `#current_page`, `#total_pages`, and `#size`.
+Such methods are supported by both [Kaminari](https://github.com/amatsuda/kaminari) or [WillPaginate](https://github.com/mislav/will_paginate),
+but you can also roll out your own paginated collection by defining these methods.
 
-### JSON adapter
+If you do not want pagination links to be automatically rendered, you may disable it by setting the `ActiveModelSerializers.config.collection_serializer` config to
+`ActiveModel::Serializer::NonPaginatedCollectionSerializer`.
 
-If you are using `JSON` adapter, pagination links will not be included automatically, but it is possible to do so using `meta` key.
+If you want to disable pagination links for a specific controller, you may set the `serializer` option to `ActiveModel::Serializer::NonPaginatedCollectionSerializer`:
 
-Add this method to your base API controller.
-
-```ruby
-def pagination_dict(object)
-  {
-    current_page: object.current_page,
-    next_page: object.next_page,
-    prev_page: object.prev_page,
-    total_pages: object.total_pages,
-    total_count: object.total_count
-  }
+``` ruby
+class PostsController < ApplicationController
+  def index
+    posts = Post.page(params[:page]).per_page(params[:per_page])
+    render json: posts, serializer: ActiveModel::Serializer::NonPaginatedCollectionSerializer
+  end
 end
 ```
 
-Then, use it on your render method.
+### Json adapter
+
+If you are using the `Json` adapter, pagination links will not be included automatically, but it is possible to handle pagination using the `meta` option:
 
 ```ruby
-render json: posts, meta: pagination_dict(posts)
+class PostsController < ApplicationController
+  def index
+    posts = Post.page(params[:page]).per_page(params[:per_page])
+    render json: posts, meta: pagination_dict(posts)
+  end
+
+  private
+
+  def pagination_dict(object)
+    {
+      current_page: object.current_page,
+      next_page: object.next_page,
+      prev_page: object.prev_page,
+      total_pages: object.total_pages,
+      total_count: object.total_count
+    }
+  end
+end
 ```
 
-ex.
+The response might look like:
 ```json
 {
   "posts": [
@@ -113,27 +116,3 @@ ex.
   }
 }
 ```
-
-You can also achieve the same result if you have a helper method that adds the pagination info in the meta tag. For instance, in your action specify a custom serializer.
-
-```ruby
-render json: @posts, each_serializer: PostPreviewSerializer, meta: meta_attributes(@post)
-```
-
-```ruby
-#expects pagination!
-def meta_attributes(resource, extra_meta = {})
-  {
-    current_page: resource.current_page,
-    next_page: resource.next_page,
-    prev_page: resource.prev_page,
-    total_pages: resource.total_pages,
-    total_count: resource.total_count
-  }.merge(extra_meta)
-end
-```
-
-
-### Attributes adapter
-
-This adapter does not allow us to use `meta` key, due to that it is not possible to add pagination links.

lib/active_model/serializable_resource.rb

@@ -2,7 +2,7 @@
 require 'active_model_serializers/adapter'
 module ActiveModel
   class SerializableResource
-    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter, :meta, :meta_key, :links])
+    ADAPTER_OPTION_KEYS = Set.new([:include, :fields, :adapter, :meta, :meta_key, :links, :serialization_context])
     include ActiveModelSerializers::Logging
 
     delegate :serializable_hash, :as_json, :to_json, to: :adapter

lib/active_model/serializer.rb

@@ -1,5 +1,6 @@
 require 'thread_safe'
 require 'active_model/serializer/collection_serializer'
+require 'active_model/serializer/non_paginated_collection_serializer'
 require 'active_model/serializer/array_serializer'
 require 'active_model/serializer/error_serializer'
 require 'active_model/serializer/errors_serializer'

lib/active_model/serializer/collection_serializer.rb

@@ -32,8 +32,7 @@ def json_key
 
       def paginated?
         object.respond_to?(:current_page) &&
-          object.respond_to?(:total_pages) &&
-          object.respond_to?(:size)
+          object.respond_to?(:total_pages)
       end
 
       protected

lib/active_model/serializer/non_paginated_collection_serializer.rb

@@ -0,0 +1,11 @@
+require 'active_model/serializer/collection_serializer'
+
+module ActiveModel
+  class Serializer
+    class NonPaginatedCollectionSerializer < CollectionSerializer
+      def paginated?
+        false
+      end
+    end
+  end
+end

lib/active_model/serializer/reflection.rb

@@ -38,6 +38,7 @@ def initialize(*)
         super
         @_links = {}
         @_include_data = true
+        @_meta = nil
       end
 
       def link(name, value = nil, &block)

lib/active_model_serializers/adapter/json_api.rb

@@ -1,3 +1,4 @@
+# coding: utf-8
 # {http://jsonapi.org/format/ JSON API specification}
 # rubocop:disable Style/AsciiComments
 # TODO: implement!
@@ -35,6 +36,7 @@ def initialize(serializer, options = {})
         super
         @include_tree = ActiveModel::Serializer::IncludeTree.from_include_args(options[:include])
         @fieldset = options[:fieldset] || ActiveModel::Serializer::Fieldset.new(options.delete(:fields))
+        @serialization_context = options[:serialization_context]
       end
 
       def default_key_transform
@@ -126,7 +128,7 @@ def success_document(options)
           hash[:links].update(instance_options[:links])
         end
 
-        if is_collection && serializer.paginated?
+        if paginate?
           hash[:links] ||= {}
           hash[:links].update(pagination_links_for(serializer, options))
         end
@@ -185,7 +187,7 @@ def fragment_cache(cached_hash, non_cached_hash)
 
       protected
 
-      attr_reader :fieldset
+      attr_reader :fieldset, :serialization_context
 
       private
 
@@ -234,6 +236,12 @@ def resource_objects_for(serializers)
         [@primary, @included]
       end
 
+      def paginate?
+        !serialization_context.nil? &&
+          serializer.respond_to?(:paginated?) &&
+          serializer.paginated?
+      end
+
       def process_resource(serializer, primary)
         resource_identifier = ResourceIdentifier.new(serializer).as_json
         return false unless @resource_identifiers.add?(resource_identifier)
@@ -499,7 +507,7 @@ def links_for(serializer)
       # prs:
       #   https://github.com/rails-api/active_model_serializers/pull/1041
       def pagination_links_for(serializer, options)
-        PaginationLinks.new(serializer.object, options[:serialization_context]).serializable_hash(options)
+        PaginationLinks.new(serializer.object, serialization_context).serializable_hash(options)
       end
 
       # {http://jsonapi.org/format/#document-meta Docment Meta}