Add a `WithPagination` concern to reuse across serializers

5 files changed, 27 insertions, 34 deletions

diff --git a/app/serializers/concerns/with_pagination.rb b/app/serializers/concerns/with_pagination.rb
new file mode 100644
index 00000000000..484c6855f7c
--- /dev/null
+++ b/app/serializers/concerns/with_pagination.rb
@@ -0,0 +1,20 @@
+module WithPagination
+  def with_pagination(request, response)
+    tap { @paginator = Gitlab::Serializer::Pagination.new(request, response) }
+  end
+
+  def paginated?
+    @paginator.present?
+  end
+
+  # super is `BaseSerializer#represent` here.
+  #
+  # we shouldn't try to paginate single resources
+  def represent(resource, opts = {})
+    if paginated? && resource.respond_to?(:page)
+      super(@paginator.paginate(resource), opts)
+    else
+      super(resource, opts)
+    end
+  end
+end
diff --git a/app/serializers/environment_serializer.rb b/app/serializers/environment_serializer.rb
index 88842a9aa75..84722f33f59 100644
--- a/app/serializers/environment_serializer.rb
+++ b/app/serializers/environment_serializer.rb
@@ -1,4 +1,6 @@
 class EnvironmentSerializer < BaseSerializer
+  include WithPagination
+
   Item = Struct.new(:name, :size, :latest)
 
   entity EnvironmentEntity
@@ -7,18 +9,10 @@ class EnvironmentSerializer < BaseSerializer
     tap { @itemize = true }
   end
 
-  def with_pagination(request, response)
-    tap { @paginator = Gitlab::Serializer::Pagination.new(request, response) }
-  end
-
   def itemized?
     @itemize
   end
 
-  def paginated?
-    @paginator.present?
-  end
-
   def represent(resource, opts = {})
     if itemized?
       itemize(resource).map do |item|
@@ -27,8 +21,6 @@ class EnvironmentSerializer < BaseSerializer
           latest: super(item.latest, opts) }
       end
     else
-      resource = @paginator.paginate(resource) if paginated?
-
       super(resource, opts)
     end
   end
diff --git a/app/serializers/group_serializer.rb b/app/serializers/group_serializer.rb
index 26e8566828b..8cf7eb63bcf 100644
--- a/app/serializers/group_serializer.rb
+++ b/app/serializers/group_serializer.rb
@@ -1,19 +1,5 @@
 class GroupSerializer < BaseSerializer
-  entity GroupEntity
-
-  def with_pagination(request, response)
-    tap { @paginator = Gitlab::Serializer::Pagination.new(request, response) }
-  end
+  include WithPagination
 
-  def paginated?
-    @paginator.present?
-  end
-
-  def represent(resource, opts = {})
-    if paginated?
-      super(@paginator.paginate(resource), opts)
-    else
-      super(resource, opts)
-    end
-  end
+  entity GroupEntity
 end
diff --git a/app/serializers/pipeline_serializer.rb b/app/serializers/pipeline_serializer.rb
index 661bf17983c..7181f8a6b04 100644
--- a/app/serializers/pipeline_serializer.rb
+++ b/app/serializers/pipeline_serializer.rb
@@ -1,16 +1,10 @@
 class PipelineSerializer < BaseSerializer
+  include WithPagination
+
   InvalidResourceError = Class.new(StandardError)
 
   entity PipelineDetailsEntity
 
-  def with_pagination(request, response)
-    tap { @paginator = Gitlab::Serializer::Pagination.new(request, response) }
-  end
-
-  def paginated?
-    @paginator.present?
-  end
-
   def represent(resource, opts = {})
     if resource.is_a?(ActiveRecord::Relation)
 
diff --git a/config/application.rb b/config/application.rb
index ca2ab83becc..bcb9f59ae3e 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -29,6 +29,7 @@ module Gitlab
                                      #{config.root}/app/models/project_services
                                      #{config.root}/app/workers/concerns
                                      #{config.root}/app/services/concerns
+                                     #{config.root}/app/serializers/concerns
                                      #{config.root}/app/finders/concerns])
 
     config.generators.templates.push("#{config.root}/generator_templates")