Encapsulate reused pagination component in a class

app/serializers/environment_serializer.rb

@@ -7,12 +7,20 @@ class EnvironmentSerializer < BaseSerializer
     tap { @itemize = true }
   end
 
+  def with_pagination(request, response)
+    tap { @paginator = Paginator.new(request, response) }
+  end
+
   def itemized?
     @itemize
   end
 
+  def paginated?
+    defined?(@paginator)
+  end
+
   def represent(resource, opts = {})
-    # resource = paginate(resource) if paginated?
+    resource = @paginator.paginate(resource) if paginated?
 
     if itemized?
       itemize(resource).map do |item|

app/serializers/paginator.rb

+class Paginator
+  include API::Helpers::Pagination
+
+  def initialize(request, response)
+    @request = request
+    @response = response
+  end
+
+  private
+
+  # Methods needed by `API::Helpers::Pagination`
+  #
+
+  attr_reader :request
+
+  def params
+    @request.query_parameters
+  end
+
+  def header(header, value)
+    @response.headers[header] = value
+  end
+end

app/serializers/pipeline_serializer.rb

 class PipelineSerializer < BaseSerializer
   class InvalidResourceError < StandardError; end
-  include API::Helpers::Pagination
-  Struct.new('Pagination', :request, :response)
 
   entity PipelineEntity
 
+  def with_pagination(request, response)
+    tap { @paginator = Paginator.new(request, response) }
+  end
+
+  def paginated?
+    defined?(@paginator)
+  end
+
   def represent(resource, opts = {})
     if paginated?
       raise InvalidResourceError unless resource.respond_to?(:page)
 
-      super(paginate(resource.includes(project: :namespace)), opts)
+      resource = resource.includes(project: :namespace)
+      super(@paginator.paginate(resource), opts)
     else
       super(resource, opts)
     end
   end
-
-  def paginated?
-    defined?(@pagination)
-  end
-
-  def with_pagination(request, response)
-    tap { @pagination = Struct::Pagination.new(request, response) }
-  end
-
-  private
-
-  # Methods needed by `API::Helpers::Pagination`
-  #
-  def params
-    @pagination.request.query_parameters
-  end
-
-  def request
-    @pagination.request
-  end
-
-  def header(header, value)
-    @pagination.response.headers[header] = value
-  end
 end