Make Apollo Federation paging types @shareable at the type level

src/HotChocolate/ApolloFederation/src/ApolloFederation/FederationTypeInterceptor.cs

@@ -1,6 +1,7 @@
 using System.Linq.Expressions;
 using System.Reflection;
 using System.Text;
+using GreenDonut.Data;
 using HotChocolate.ApolloFederation.Resolvers;
 using HotChocolate.ApolloFederation.Types;
 using HotChocolate.Configuration;
@@ -17,6 +18,8 @@ namespace HotChocolate.ApolloFederation;
 
 internal sealed class FederationTypeInterceptor : TypeInterceptor
 {
+    private const string PageCursorTypeName = "PageCursor";
+
     private static readonly MethodInfo s_matches =
         typeof(ReferenceResolverHelper)
             .GetMethod(
@@ -117,23 +120,20 @@ public override IEnumerable<TypeReference> RegisterMoreTypes(
             yield return _typeInspector.GetTypeRef(typeof(LinkDirective));
         }
 
-        // The page info fields are made shareable in OnAfterCompleteName for any type
-        // named "PageInfo". That match is by name, so it also covers the page info type
-        // that is inferred from PageConnection<T> (runtime type PageInfo) and not just the
-        // built-in PageInfoType. We therefore have to register the shareable directive for
-        // any discovered page info object type, otherwise the directive cannot be resolved
-        // when the fields are completed.
-        if (discoveryContexts.Any(t => IsPageInfoType(t.Type))
+        // PageInfo and PageCursor are marked @shareable in OnBeforeCompleteType, which
+        // requires the directive type to be registered when either of them is discovered.
+        if (discoveryContexts.Any(t => IsPagingType(t.Type))
             && discoveryContexts.All(t => t.Type is not DirectiveType<ShareableDirective>))
         {
             yield return _typeInspector.GetTypeRef(typeof(ShareableDirective));
         }
     }
 
-    private static bool IsPageInfoType(TypeSystemObject type)
+    private static bool IsPagingType(TypeSystemObject type)
         => type is PageInfoType
             || (type is IRuntimeTypeProvider { RuntimeType: { } runtimeType }
-                && typeof(IPageInfo).IsAssignableFrom(runtimeType));
+                && (typeof(IPageInfo).IsAssignableFrom(runtimeType)
+                    || runtimeType == typeof(PageCursor)));
 
     public override void OnBeforeCompleteName(
         ITypeCompletionContext completionContext,
@@ -156,20 +156,6 @@ public override void OnAfterCompleteName(
             return;
         }
 
-        // if we find a PagingInfo we will make all fields sharable.
-        if (configuration is ObjectTypeConfiguration typeCfg
-            && typeCfg.Name.Equals(PageInfoType.Names.PageInfo))
-        {
-            foreach (var fieldCfg in typeCfg.Fields)
-            {
-                if (fieldCfg.Directives.All(t => t.Value is not ShareableDirective))
-                {
-                    var typeRef = TypeReference.CreateDirective(_typeInspector.GetType(typeof(ShareableDirective)));
-                    fieldCfg.Directives.Add(new DirectiveConfiguration(ShareableDirective.Default, typeRef));
-                }
-            }
-        }
-
         var hasRuntimeType = (IRuntimeTypeProvider)configuration;
         var type = hasRuntimeType.RuntimeType;
 
@@ -358,6 +344,8 @@ public override void OnBeforeCompleteType(
         AddServiceTypeToQueryType(
             completionContext,
             configuration);
+
+        ApplyShareableToPagingType(configuration);
     }
 
     public override void OnAfterMakeExecutable(
@@ -497,6 +485,23 @@ private void AddServiceTypeToQueryType(
         }
     }
 
+    private void ApplyShareableToPagingType(TypeSystemConfiguration configuration)
+    {
+        // PageInfo and PageCursor are shared by every subgraph that exposes a connection,
+        // so they are marked @shareable at the type level.
+        if (_context.GetFederationVersion() == FederationVersion.Federation10
+            || configuration is not ObjectTypeConfiguration typeCfg
+            || typeCfg.Name is not (PageInfoType.Names.PageInfo or PageCursorTypeName)
+            || typeCfg.Directives.Any(t => t.Value is ShareableDirective))
+        {
+            return;
+        }
+
+        var typeRef = TypeReference.CreateDirective(
+            _typeInspector.GetType(typeof(ShareableDirective)));
+        typeCfg.Directives.Add(new DirectiveConfiguration(ShareableDirective.Default, typeRef));
+    }
+
     private void ApplyMethodLevelReferenceResolvers(
         ObjectType objectType,
         ObjectTypeConfiguration objectTypeCfg)

src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/PageConnectionFederationTests.cs

@@ -1,4 +1,6 @@
+using HotChocolate.ApolloFederation.Types;
 using HotChocolate.Execution;
+using HotChocolate.Types;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace HotChocolate.ApolloFederation;
@@ -19,4 +21,20 @@ public async Task PageConnection_Field_With_ApolloFederation_Builds_Schema()
         // assert
         schema.MatchSnapshot();
     }
+
+    [Fact]
+    public async Task PageConnection_Field_With_Explicit_Shareable_PageCursor_Builds_Schema()
+    {
+        // arrange & act
+        var schema = await new ServiceCollection()
+            .AddGraphQL()
+            .AddApolloFederation()
+            .AddImplementationFirstTypes()
+            .AddPagingArguments()
+            .AddTypeExtension(new ObjectTypeExtension(d => d.Name("PageCursor").Shareable()))
+            .BuildSchemaAsync(cancellationToken: TestContext.Current.CancellationToken);
+
+        // assert
+        schema.MatchSnapshot();
+    }
 }

src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/__snapshots__/PageConnectionFederationTests.PageConnection_Field_With_ApolloFederation_Builds_Schema.graphql

@@ -50,27 +50,27 @@ type EmployeeEdge {
 }
 
 "A cursor that points to a specific page."
-type PageCursor {
+type PageCursor @shareable {
   "The page number."
   page: Int!
   "The cursor."
   cursor: String!
 }
 
 "Information about pagination in a connection."
-type PageInfo {
+type PageInfo @shareable {
   "Indicates whether more edges exist following the set defined by the clients arguments."
-  hasNextPage: Boolean! @shareable
+  hasNextPage: Boolean!
   "Indicates whether more edges exist prior the set defined by the clients arguments."
-  hasPreviousPage: Boolean! @shareable
+  hasPreviousPage: Boolean!
   "When paginating backwards, the cursor to continue."
-  startCursor: String @shareable
+  startCursor: String
   "When paginating forwards, the cursor to continue."
-  endCursor: String @shareable
+  endCursor: String
   "A list of cursors to continue paginating forwards."
-  forwardCursors: [PageCursor!]! @shareable
+  forwardCursors: [PageCursor!]!
   "A list of cursors to continue paginating backwards."
-  backwardCursors: [PageCursor!]! @shareable
+  backwardCursors: [PageCursor!]!
 }
 
 "The _Any scalar is used to pass representations of entities from external services into the root _entities field for execution. Validation of the _Any scalar is done by matching the __typename and @external fields defined in the schema."

src/HotChocolate/ApolloFederation/test/ApolloFederation.ImplementationFirst/__snapshots__/PageConnectionFederationTests.PageConnection_Field_With_Explicit_Shareable_PageCursor_Builds_Schema.graphql

@@ -0,0 +1,91 @@
+schema
+  @link(
+    url: "https://specs.apollo.dev/federation/v2.6"
+    import: ["@shareable", "@tag", "FieldSet"]
+  ) {
+  query: Query
+}
+
+type Query {
+  employeeByPageTest(
+    "Returns the first _n_ elements from the list."
+    first: Int
+    "Returns the elements in the list that come after the specified cursor."
+    after: String
+    "Returns the last _n_ elements from the list."
+    last: Int
+    "Returns the elements in the list that come before the specified cursor."
+    before: String
+  ): EmployeeConnection!
+  _service: _Service!
+}
+
+"This type provides a field named sdl: String! which exposes the SDL of the service's schema. This SDL (schema definition language) is a printed version of the service's schema including the annotations of federation directives. This SDL does not include the additions of the federation spec."
+type _Service {
+  sdl: String!
+}
+
+type Employee {
+  empId: Int!
+  name: String!
+}
+
+"A connection to a list of items."
+type EmployeeConnection {
+  "A list of edges."
+  edges: [EmployeeEdge!]
+  "A flattened list of the nodes"
+  nodes: [Employee!]
+  "Information to aid in pagination."
+  pageInfo: PageInfo!
+  "Identifies the total count of items in the connection."
+  totalCount: Int!
+}
+
+type EmployeeEdge {
+  "The item at the end of the edge."
+  node: Employee!
+  "A cursor for use in pagination."
+  cursor: String!
+}
+
+"A cursor that points to a specific page."
+type PageCursor @shareable {
+  "The page number."
+  page: Int!
+  "The cursor."
+  cursor: String!
+}
+
+"Information about pagination in a connection."
+type PageInfo @shareable {
+  "Indicates whether more edges exist following the set defined by the clients arguments."
+  hasNextPage: Boolean!
+  "Indicates whether more edges exist prior the set defined by the clients arguments."
+  hasPreviousPage: Boolean!
+  "When paginating backwards, the cursor to continue."
+  startCursor: String
+  "When paginating forwards, the cursor to continue."
+  endCursor: String
+  "A list of cursors to continue paginating forwards."
+  forwardCursors: [PageCursor!]!
+  "A list of cursors to continue paginating backwards."
+  backwardCursors: [PageCursor!]!
+}
+
+"The _Any scalar is used to pass representations of entities from external services into the root _entities field for execution. Validation of the _Any scalar is done by matching the __typename and @external fields defined in the schema."
+scalar _Any
+
+"Scalar representing a set of fields."
+scalar FieldSet
+
+"Links definitions within the document to external schemas."
+directive @link(
+  "Gets imported specification url."
+  url: String!
+  "Gets optional list of imported element names."
+  import: [String!]
+) repeatable on SCHEMA
+
+"Indicates that given object and/or field can be resolved by multiple subgraphs."
+directive @shareable repeatable on OBJECT | FIELD_DEFINITION

src/HotChocolate/ApolloFederation/test/ApolloFederation.Tests/__snapshots__/BuiltInTypesShareableTests.Ensure_PagingInfo_Is_Shareable.graphql

@@ -48,15 +48,15 @@ type AddressesEdge {
 }
 
 "Information about pagination in a connection."
-type PageInfo {
+type PageInfo @shareable {
   "Indicates whether more edges exist following the set defined by the clients arguments."
-  hasNextPage: Boolean! @shareable
+  hasNextPage: Boolean!
   "Indicates whether more edges exist prior the set defined by the clients arguments."
-  hasPreviousPage: Boolean! @shareable
+  hasPreviousPage: Boolean!
   "When paginating backwards, the cursor to continue."
-  startCursor: String @shareable
+  startCursor: String
   "When paginating forwards, the cursor to continue."
-  endCursor: String @shareable
+  endCursor: String
 }
 
 "The _Any scalar is used to pass representations of entities from external services into the root _entities field for execution. Validation of the _Any scalar is done by matching the __typename and @external fields defined in the schema."

src/HotChocolate/ApolloFederation/test/ApolloFederation.Tests/__snapshots__/BuiltInTypesShareableTests.Ensure_PagingInfo_Is_Shareable_When_Shareable_Already_Registered.graphql

@@ -48,15 +48,15 @@ type AddressesEdge {
 }
 
 "Information about pagination in a connection."
-type PageInfo {
+type PageInfo @shareable {
   "Indicates whether more edges exist following the set defined by the clients arguments."
-  hasNextPage: Boolean! @shareable
+  hasNextPage: Boolean!
   "Indicates whether more edges exist prior the set defined by the clients arguments."
-  hasPreviousPage: Boolean! @shareable
+  hasPreviousPage: Boolean!
   "When paginating backwards, the cursor to continue."
-  startCursor: String @shareable
+  startCursor: String
   "When paginating forwards, the cursor to continue."
-  endCursor: String @shareable
+  endCursor: String
 }
 
 "The _Any scalar is used to pass representations of entities from external services into the root _entities field for execution. Validation of the _Any scalar is done by matching the __typename and @external fields defined in the schema."