6 files changed, 73 insertions, 35 deletions
diff --git a/app/graphql/types/packages/composer/details_type.rb b/app/graphql/types/packages/composer/details_type.rb
deleted file mode 100644
index 8c6845a6fb3..00000000000
--- a/app/graphql/types/packages/composer/details_type.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-# frozen_string_literal: true
-
-module Types
-  module Packages
-    module Composer
-      class DetailsType < Types::Packages::PackageType
-        graphql_name 'PackageComposerDetails'
-        description 'Details of a Composer package'
-
-        authorize :read_package
-
-        field :composer_metadatum, Types::Packages::Composer::MetadatumType, null: false, description: 'The Composer metadatum.'
-      end
-    end
-  end
-end
diff --git a/app/graphql/types/packages/composer/metadatum_type.rb b/app/graphql/types/packages/composer/metadatum_type.rb
index a97818b1fb8..9d4ce3cebd4 100644
--- a/app/graphql/types/packages/composer/metadatum_type.rb
+++ b/app/graphql/types/packages/composer/metadatum_type.rb
@@ -4,8 +4,8 @@ module Types
   module Packages
     module Composer
       class MetadatumType < BaseObject
-        graphql_name 'PackageComposerMetadatumType'
-        description 'Composer metadatum'
+        graphql_name 'ComposerMetadata'
+        description 'Composer metadata'
 
         authorize :read_package
 
diff --git a/app/graphql/types/packages/metadata_type.rb b/app/graphql/types/packages/metadata_type.rb
new file mode 100644
index 00000000000..26c43b51a69
--- /dev/null
+++ b/app/graphql/types/packages/metadata_type.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module Types
+  module Packages
+    class MetadataType < BaseUnion
+      graphql_name 'PackageMetadata'
+      description 'Represents metadata associated with a Package'
+
+      possible_types ::Types::Packages::Composer::MetadatumType
+
+      def self.resolve_type(object, context)
+        case object
+        when ::Packages::Composer::Metadatum
+          ::Types::Packages::Composer::MetadatumType
+        else
+          # NOTE: This method must be kept in sync with `PackageWithoutVersionsType#metadata`,
+          # which must never produce data that this discriminator cannot handle.
+          raise 'Unsupported metadata type'
+        end
+      end
+    end
+  end
+end
diff --git a/app/graphql/types/packages/package_type.rb b/app/graphql/types/packages/package_type.rb
index b13d16e91c6..331898a1e84 100644
--- a/app/graphql/types/packages/package_type.rb
+++ b/app/graphql/types/packages/package_type.rb
@@ -2,26 +2,13 @@
 
 module Types
   module Packages
-    class PackageType < BaseObject
+    class PackageType < PackageWithoutVersionsType
       graphql_name 'Package'
       description 'Represents a package in the Package Registry'
-
       authorize :read_package
 
-      field :id, GraphQL::ID_TYPE, null: false, description: 'The ID of the package.'
-      field :name, GraphQL::STRING_TYPE, null: false, description: 'The name of the package.'
-      field :created_at, Types::TimeType, null: false, description: 'The created date.'
-      field :updated_at, Types::TimeType, null: false, description: 'The updated date.'
-      field :version, GraphQL::STRING_TYPE, null: true, description: 'The version of the package.'
-      field :package_type, Types::Packages::PackageTypeEnum, null: false, description: 'The type of the package.'
-      field :tags, Types::Packages::PackageTagType.connection_type, null: true, description: 'The package tags.'
-      field :project, Types::ProjectType, null: false, description: 'Project where the package is stored.'
-      field :pipelines, Types::Ci::PipelineType.connection_type, null: true, description: 'Pipelines that built the package.'
-      field :versions, Types::Packages::PackageType.connection_type, null: true, description: 'The other versions of the package.'
-
-      def project
-        Gitlab::Graphql::Loaders::BatchModelLoader.new(Project, object.project_id).find
-      end
+      field :versions, ::Types::Packages::PackageWithoutVersionsType.connection_type, null: true,
+        description: 'The other versions of the package.'
     end
   end
 end
diff --git a/app/graphql/types/packages/package_type_enum.rb b/app/graphql/types/packages/package_type_enum.rb
index 9713c9d49b1..e2b5cf3163e 100644
--- a/app/graphql/types/packages/package_type_enum.rb
+++ b/app/graphql/types/packages/package_type_enum.rb
@@ -5,7 +5,7 @@ module Types
     class PackageTypeEnum < BaseEnum
       PACKAGE_TYPE_NAMES = {
         pypi: 'PyPI',
-        npm: 'NPM'
+        npm: 'npm'
       }.freeze
 
       ::Packages::Package.package_types.keys.each do |package_type|
diff --git a/app/graphql/types/packages/package_without_versions_type.rb b/app/graphql/types/packages/package_without_versions_type.rb
new file mode 100644
index 00000000000..9c6bb37e6cc
--- /dev/null
+++ b/app/graphql/types/packages/package_without_versions_type.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Types
+  module Packages
+    class PackageWithoutVersionsType < ::Types::BaseObject
+      graphql_name 'PackageWithoutVersions'
+      description 'Represents a version of a package in the Package Registry'
+
+      authorize :read_package
+
+      field :id, ::Types::GlobalIDType[::Packages::Package], null: false,
+            description: 'ID of the package.'
+
+      field :name, GraphQL::STRING_TYPE, null: false, description: 'Name of the package.'
+      field :created_at, Types::TimeType, null: false, description: 'Date of creation.'
+      field :updated_at, Types::TimeType, null: false, description: 'Date of most recent update.'
+      field :version, GraphQL::STRING_TYPE, null: true, description: 'Version string.'
+      field :package_type, Types::Packages::PackageTypeEnum, null: false, description: 'Package type.'
+      field :tags, Types::Packages::PackageTagType.connection_type, null: true, description: 'Package tags.'
+      field :project, Types::ProjectType, null: false, description: 'Project where the package is stored.'
+      field :pipelines, Types::Ci::PipelineType.connection_type, null: true,
+        description: 'Pipelines that built the package.'
+      field :metadata, Types::Packages::MetadataType, null: true,
+        description: 'Package metadata.'
+
+      def project
+        Gitlab::Graphql::Loaders::BatchModelLoader.new(Project, object.project_id).find
+      end
+
+      # NOTE: This method must be kept in sync with the union
+      # type: `Types::Packages::MetadataType`.
+      #
+      # `Types::Packages::MetadataType.resolve_type(metadata, ctx)` must never raise.
+      def metadata
+        case object.package_type
+        when 'composer'
+          object.composer_metadatum
+        else
+          nil
+        end
+      end
+    end
+  end
+end