1 files changed, 90 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/pagination/active_record_array_connection.rb b/lib/gitlab/graphql/pagination/active_record_array_connection.rb
new file mode 100644
index 00000000000..9e40f79b2fd
--- /dev/null
+++ b/lib/gitlab/graphql/pagination/active_record_array_connection.rb
@@ -0,0 +1,90 @@
+# frozen_string_literal: true
+
+# Connection for an array of Active Record instances.
+# Resolvers needs to handle cursors (before and after).
+# This connection will handle (first and last).
+# Supports batch loaded items.
+# Expects the array to use a fixed DESC order. This is similar to
+# ExternallyPaginatedArrayConnection.
+module Gitlab
+  module Graphql
+    module Pagination
+      class ActiveRecordArrayConnection < GraphQL::Pagination::ArrayConnection
+        include ::Gitlab::Graphql::ConnectionCollectionMethods
+        prepend ::Gitlab::Graphql::ConnectionRedaction
+
+        delegate :<<, to: :items
+
+        def nodes
+          load_nodes
+
+          @nodes
+        end
+
+        def next_page?
+          load_nodes
+
+          if before
+            true
+          elsif first
+            limit_value < items.size
+          else
+            false
+          end
+        end
+
+        def previous_page?
+          load_nodes
+
+          if after
+            true
+          elsif last
+            limit_value < items.size
+          else
+            false
+          end
+        end
+
+        # see https://graphql-ruby.org/pagination/custom_connections#connection-wrapper
+        alias_method :has_next_page, :next_page?
+        alias_method :has_previous_page, :previous_page?
+
+        def cursor_for(item)
+          # item could be a batch loaded item. Sync it to have the id.
+          cursor = { 'id' => Gitlab::Graphql::Lazy.force(item).id.to_s }
+          encode(cursor.to_json)
+        end
+
+        # Part of the implied interface for default objects for BatchLoader: objects must be clonable
+        def dup
+          self.class.new(
+            items.dup,
+            first: first,
+            after: after,
+            max_page_size: max_page_size,
+            last: last,
+            before: before
+          )
+        end
+
+        private
+
+        def limit_value
+          # note: only first _or_ last can be specified, not both
+          @limit_value ||= [first, last, max_page_size].compact.min
+        end
+
+        def load_nodes
+          @nodes ||= begin
+            limited_nodes = items
+
+            limited_nodes = limited_nodes.first(first) if first
+            limited_nodes = limited_nodes.last(last) if last
+
+            limited_nodes
+          end
+        end
+      end
+    end
+  end
+end